Sunday, December 16, 2018

Learning to speak Italian… again!

I really have to stop throwing out internet bids on “interesting” bikes and forgetting that I did it until I receive notice that I have “won the auction”.

Those of you who have followed my ramblings over the past 10 years (or more) might recall that I acquired a somewhat troublesome Benelli Sei (750 six cylinder) machine from a local seller who had had it since the 1970s. That bike was fun to ride and sounded amazing… when it would start. Even a $500 ignition system never insured that the engine would fire up easily. That, along with the factory defective transmission gearset (there was a recall that the bike never received) led me to let it go to a local Italian bike dealer who had the bike restored.

So, here we are again, with almost the same bike, but with fewer cylinders this time. The Benelli Quattro 500 is the Honda CB500 engine clone in virtually the same chassis as the Sei. The big departure is that instead of a double disc Brembo front brake, it has a double-sided drum brake system with 4 brake shoes up front.

The bike caught my eye on some Internet link to a big auction in Wisconsin in mid Oct. It was open to internet bids a few weeks ahead of the actual date, so I thought I would test the waters to see how much interest there was in this rare machine. Benelli updated the models with the double disc brake wheel later on, but few of these bikes were probably ever sold in the US in either form. I do recall seeing one for sale locally a number of years ago and visiting the seller’s place to see it in the flesh/metal. It, too, was a drum-brake model, but it wasn’t running and I shied away from it due to lack of parts and general knowledge of the series.

By the time I paid for this bike, plus a hefty 18% buyers fee and rounded up a U-ship guy to haul it out for $450, the initial bid cost had increased by 50% again. All that was shown in the auction page was both sides of the green bike and a short sentence about the frame number and perhaps the mileage on the odometer.  The auction company did provide a WI title a few weeks after the bike arrived, which is helpful for getting a CA title for the bike, but you still have to jump through the DMV/CHP hoops to finalize the paperwork.

The main source for replacement parts is a company in Germany, who seemed to have gathered up all the remaining Benelli parts for all the models they could find. They have microfiche illustrations on-line and generally ship parts out quickly and at reasonable prices, all things considered. I did inquire about the H-shaped molded fuel hose connector in advance of receiving the bike and they did not have a replacement part for that item. There are four carburetors and two petcocks to connect all the plumbing together so I will have to round up T-fittings to get it all fueling properly.
                                                                    Auction photo

The bike arrived within 10 days from the auction, riding tail-gunner on the back of a long, double-axle open trailer. At 20 feet, it doesn’t look TOO bad, but as you got closer the condition issues became more and more apparent. Fortunately, it did have some air in the tires and the 4 shoe front brake did function to a point. The friendly driver helped me push it up the driveway and into the awaiting bike lift for future repairs and a deeper inspection of all systems.  It was one of those heart-stopping moments where you say to yourself, “What did I get myself into now?”

The first look revealed that there were NO spark plugs in the engine, no ignition switch key provided and the engine was LOCKED UP solid. The first thing to do was to squirt WD40 penetrating oil down each spark plug hole and hope that it would work some magic on the stuck pistons.

The design of the battery box is such that you cannot remove the back side of the air filter box to service the filter. Removal of various attached electrical components finally allowed the battery box removal. At that point, the bolt holding the filter cover turned out to be part of the inside of the housing, not accessible unless you remove the carburetors and airbox. The carburetors are connected with intake manifold rubbers which attach to intake manifolds which are bolted onto the back side of the cylinder head. The air filter box connects to the carburetors with short connectors, which unlike the outside angled versions on a CB500 Honda, are all straight-back designed parts. Pulling the connectors off the air box and back off the carburetors allowed for carburetor removal. One of the carburetor tops was missing and the throttle cable had already been disconnected. SOMEONE had been in there before, probably trying to get it running sometime in the past 10-20 years.

On the plus side, the odometer only showed 1506 miles and the original Pirelli branded tires were showing little wear, which seemed to verify the miles shown on the speedometer. There was rust everywhere on chromed parts, other than the fenders, which were unaffected for some reason. There was surface rust inside the fuel tank, of course, but the carburetors were clean inside the bowls. The plastic meter box, which mounts to the upper fork bridge with a couple of bolts was broken at both attachment points.  It was déjà vu all over again, as the basic architecture of the Quattro 500 is nearly identical to the 6 cylinder Sei. The Sei had double disc brakes up front, but both bikes shared the same rear hub and suspension. The Sei has alloy rims, where the cheaper 500 was left with chrome steel hoops, which were both rusted badly on this machine.

The fork ears had been chromed, along with the front brake hub stays from the factory. The brake stays were suffering from peeling chrome and the fork ears were in similar condition. The chromed headlight bucket was somewhat better, but the headlight rim chrome was badly pitted.  The 4into 4 mufflers were solid, but with surface rust and pitting down in the creases. The header pipes were still in remarkably good condition, however.

Once the carburetors were removed, work commenced on getting the top end of the engine removed for damage assessment. Unlike Honda, Benelli engineers used #1 Phillips head screws to retain the top rocker arm cover. Fortunately, they mostly loosened with a few blows of the impact driver with a matching driver tip. More challenges were revealed when two of the Allen screws that hold the top cover end caps wouldn’t come out, stripping the hex heads of the 5mm screws. After trying various methods of removal, the heads were drilled off so the caps could be taken off. The end caps cover the last two end screws that hold the top cover to the cylinder head. The screws thread into the ends of the rocker arm shafts and there was no apparent reason for two to come off and two to be firmly entrenched in their positions. It took about a half hour of careful drilling the screws out of the ends of the shafts, then rethreading the holes successfully. The cover then came off easily revealing shiny metal parts inside. The rocker arm pads were all like new and the camshaft lobes appeared to be barely broken in.

The camshaft is secured to the camsprocket with two bolts, but somehow the engine had stopped with both bolts lying right at horizontal positions. It’s tight quarters in there, so although the camshaft bolts could be accessed (remember the engine was frozen), you can’t back them all the way out of the camshaft sprocket as the heads hit the inside of the cylinder head opening. I tried to loosen the camsprocket bolts with an open ended wrench, but they didn’t budge at all. I figured that the bolts had been installed with Lock-tite thread locker, so the only option was to try to loosen them with a large sharp chisel. The chisel was able to catch a corner of the bolts at just the right angle, but it took considerable amount of hammering to get them to begin to rotate loose from the camshaft bolt holes.

Eventually, both bolts were loosened successfully, but couldn’t be removed due to their proximity to the edges of the cylinder head. A Dremel tool with a cut-off wheel was used to cut half of the bolt head away just enough to allow the bolt to be removed from the forward bolt hole. The rear one remained in place, however. Using a long-handled adjustable wrench, I applied some torque on the crankshaft bolt, hoping that the engine would give just a little bit. Suddenly, the crankshaft turned about 10 degrees and the camshaft bolt was then clear of the cylinder head for removal.  With the camchain free of the camshaft, the engine was turned back and forth a few times, finally allowing for full rotation of the crankshaft and full movement of the pistons.

The camchain tensioner bolts to the back of the head and cylinder with 2 bolts, but unlike Honda’s design, the mechanism can’t be locked in place for removal. When the bolts were removed, the tensioner spring wanted to push up against the back of the camchain, preventing removal of the camchain from the sprocket teeth. The tensioner was pulled upwards, but hit the frame backbone tube before it was clear of the cylinder head. Finally, it appeared that the tensioner could be compressed with my fingers and the whole unit rotated 90 degrees, which then allowed the top to be tipped over and just clear of the frame tube.

Once the camchain was off the camsprocket, the camshaft was removed and a wire attached to the camchain to prevent it from dropping too far into the engine.  The cylinder head is attached with a series of flanged nuts and washers, some of which are sealed off by little rubber plugs in the head.  With all the nuts removed, the head pulled up with a little nudging here and there. The valves had quite a bit of soft carbon on them, but showed little signs of use. The now-exposed piston crowns showed some signs of varnish, carbon and moisture corrosion. The cylinder bores had some pitting around the edges of where the pistons were sitting for so many years. The corrosion had eaten into the bores just enough to catch a fingernail on the edges, so the choice was to pull the cylinders for a re-bore.

A set of .50 aftermarket Honda CB500 pistons/rings were ordered up from Japan for $125 and the cylinders will go off to my favorite machine shop for $160 of machine work. Lots of scraping was involved to get the leftover gasket material off the engine cases, all the while trying to keep the loose bits from entering the open bores in the crankcase. The pistons all came off of the pins with little fuss, so  there is no concern about damaged pin bores in the rods.

Progressing slowly…
The a/m pistons came in from Japan in about a week. My machinist bored the cylinders and noted that one piston was a bit smaller than the other three, so bored the holes accordingly. After some wire-brushing to clean off excess corrosion, the cylinders got a bit of color added back. Benelli actually painted the cylinder blocks gold and the heads black from the factory! After an hour of careful prepping and assembly, the cylinders glided onto the pistons and the assembly awaited the completion of the cylinder head.

The cylinder head was disassembled and de-carboned. All the valve faces and seats looked great, but valve stem seals were hardened, so were replaced with gasket kit parts. In the process of reassembly one of the valve stem keepers dematerialized and could not be recovered despite an extensive search of the immediate area. I discovered that the valves were 5.5mm stems like the Honda valve stem sizes, but Honda keepers didn’t fit, so replacements have to come from Germany.
I was ordering parts from Benelli-Bauer anyway, as they are one of the last couple of resources for NOS Benelli parts. They can supply replacement instrument cases and most everything else that I have asked for so far.

In the meantime, I decided to go the poor-man’s route and have the rims powdercoated satin black, along with the formerly-chromed fork ears. Some new tires were ordered and after all the spokes were cleaned up, the finished rims were re-spoked back to the de-rusted hubs. There was extensive amounts of rust inside the drums, however it did clean off with extensive use of wire wheels and abrasives. The brake shoes were glazed and had a thin film of corrosion embedded into the faces. A little light sanding brought back the original surfaces however.

Rather than purchase all the Benelli gasket parts, one-by-one, I just ordered up a whole CB500 Four gasket kit and installed all of those parts without issue. Apart from the slightly-angled forward cylinders, much of the top end components are exact dimensions of Honda’s OEM CB500 designs.
The parts order from Germany took almost 2 weeks to arrive, so to speed up the assembly process an OEM Honda exhaust valve was ordered to match the keepers that were already purchased, but didn’t fit the groove pattern on the Benelli valve stem.  Problem solved and the cylinder head was bolted down, torqued to specs.  Two new camsprocket bolts were ordered to replace the butchered ones and the rest of the original parts reinstalled.

My experience with the Benelli Sei mirrored the current one of the Quattro. The intake manifold rubbers were broken/cracked causing obvious air leaks. On the Sei, I ordered up OEM Honda manifolds and installed a set on the Sei, which did not have the original air box in place. The manifolds were a little longer than the originals, but it didn’t matter because of the pod filter installation. The Quattro carb/manifold/airbox combo is a REALLY tight fit; even worse than a standard CB500-550 setup.

Sadly, after the long wait for the box of parts from Germany, it became obvious that the intake manifolds shipped were of two types/lengths. Three might have been actual Sei units and one an actual Quattro replacement part.  A message back to Germany, accompanied with photos, confirmed the mistake and a promise to ship the correct parts came back quickly.

Eyeballing the manifold situation, it seemed that the “wrong ones” could be used in the interim but because they were of a thicker material the original manifold clamps wouldn’t reach around to fit the increased diameter. Also, the process of wedging the carburetor rack in between the bolt-on manifold stubs on the head it became apparent that there was left no room for the carburetor rack to fit between the two components. I would imagine that the “correct” way to remove/replace the carburetors is to loosen the engine mounts and tilt it forward, which is required on a CBX Honda Six. 

To override that necessity, I removed the manifold stub bolts and replaced them with bolts, so I could slide the whole assembly in laterally and fit the carb inlets to the new air cleaner box connectors. I could only use 2 of the original rubber manifold clamps on the one correct manifold that was supplied, so the other three were clamped with 2” hose clamps that I had on hand. The two rubber manifold types have different ribbed patterns, but they were close enough to allow a tight fit once paired with new clamps.

Another couple of hours were spent doing R&R on the meter box installation, which was a snug fit for all the components. All the wiring connections to the instrument warning lights needed to be disconnected so the harness could be pulled through the small slit on the bottom of the meter box housing. The wiring diagrams found online were all in German or Italian and of very faint and small drawings. That had to be reworked on the computer and printed out to help with the wiring installation. The recommended replacement Yuasa battery had side posts instead of top posts, so some angled adapters were fabricated. Fortunately, apart from some blown out bulbs and some that had melted the plastic upper meter housing plate, the electrics mostly came to life without blowing any fuses. The fuse block is typically mid-20th Century design with little bullet ended ceramic fuses and flimsy fuse holder tabs.  Corrosion had built up on the ends, so everything needed cleaning to promote good electrical connectivity.

The ignition points were corroded, so required more cleaning and adjustment. I hesitantly tried the starter button and the engine began to spin over, somewhat slowly, but the result was encouraging. 
The fuel tank was cleaned and sealed with 2 part Caswell epoxy coatings. New generic Italian style petcocks were located and installed to complete the fuel tank repairs. Some ¼” T fittings were purchased at the auto parts store and little pieces of 5.5 OEM Honda fuel line were cut up and fitted to tie the fuel system components together.
Running and nearly ready to sell.

Initially the engine spun over, but wouldn’t fire up, even with the choke fully applied. There is a lot of friction with new pistons/rings and a lack of ring sealing in the beginning which caused some difficulties in getting the engine spun over fast enough to get everything synched up, but with a jumper system in place, the long-dormant engine finally fired up on all cylinders, sounding quite like a copy of a Honda CB500 Four with 4 into 4 exhaust pipes. The carbs were fussy, at first. The idle speed was erratic, either too low or too high, probably owing to a sticking spark advancer unit.

The engine does start and run, but not idle well. The charging system light stayed ON, so the left generator cover was removed for inspection. The Bosch charging system uses a set of brushes to contact the slip rings on the end of the rotor shaft, not unlike an automotive alternator. While the components all appeared to be in good condition and electrical wiring checked okay, the whole outer brush/stator assembly was basically just floating on the end of the rotor shaft because the four 5mm mounting bolts were MISSING! Long 5x45mm bolts are not easily found locally, so a quick look online gave some clues about where to find them. I called local hardware/bolt stores and discovered that there were some in stock… 45 of them in a box! I only needed 3, but the whole box was only $6 and change, so I bought the box and have more than 40 to share with anyone out there who might need such a fastener.

The bike continued to be hard starting, didn’t want to idle and one carburetor began to overflow due to a failed plastic float assembly. Carb kits were ordered and the wait continues for replacement intake manifold rubber connectors. All the spares will go with the bike, which has been put up for sale now.

As what has happened several times in the past, I am facing surgery again, this time for a worn out ankle. The recovery requires 3 months of non-weight bearing on the right foot, so getting this project wrapped up and ready for sale has become a race against time.
A quick trip to the CHP office for verification and then back to DMV to push through the completed paperwork was successful, so the bike can be officially titled in the state of California. Having a titled bike helps the sales process immensely so I always do the legwork to get the paperwork in order for the next owner.

 I have to promise myself NOT to repeat this process again, especially with another rare Italian Honda copy model, such as the Quattro 500. In an eerie coincidence, during the Quattro project, I was contacted by a man who I met at the January 2018 Mods and Rockers ride event. He had bought a storage unit full of bikes, including a silver 1976 Benelli Sei! He wasn’t going to sell it right away (although there is always a price that works in the end), but needed someone’s help to get his running properly. I offered to help, but warned him of my upcoming surgery and lack of ability to do motorcycle work for at least three months afterwards. Unfortunately, the sands of time have about run out on that offer…

Bill Silver            aka “MrItalianHonda” for the end of 2018.

Tuesday, November 6, 2018

It’s raining CB92s this month…..

My primary focus on vintage Hondas has been the variations of the 250-305cc models for more than a decade.  Having owned, repaired and overhauled numerous vintage big twins, I am perfectly at home with those models.

Honda’s CB92 Super Sport machines are extremely rare in the US, having only received about 1,000 machines in the 1960-62 era and many of those were supposedly the racing versions. I owned CB92 #24 about 30 years ago, which was a bike originally sold here in San Diego. In the years since about half a dozen more have come my way and were resold without taking on full restorations. Obviously, after 58 years, the parts sources are very thin. Additionally, the changes made during production, complicates the picture even further.

Honda began production in 1959 with both a 125cc CB92 and a companion 150cc version CB95. Bear in mind that these were newly designed OHC twins which revved to 10k rpms, but only carried a little over one quart of oil in the crankcases. Early bikes suffered crankshaft failures and left side piston seizures when run hard, especially of the oil level dropped below the safe mark.

From 1959 through 1962, there were three different crankshafts and a matching number of crankcase changes to follow. The first generation crankshafts had a 1mm larger center main bearing than the end bearings, all located in the cases with split half ring retainers. At high rpms the bearings could actually rotate in the cases and not enough oil was passing through the crankshaft to feed the left side crankpin.  Honda did an unusual stopgap modification by machining an oil passage in the base of the cylinder block that lead from the oil feed stud hole across the back and into a window that was machined in the rear of the left side cylinder bore.  A special gasket was created to match the oil channel work.  The early cases featured a “rear breather” design that collected and separated the oil solids from the crankcase vapors at high speeds and allowed just the separated air to escape.

The second generation featured main bearings of all the same diameter, but the center main was locked in place with a locating pin to ensure that it was getting a constant oil feed from above. The end bearings continued to be of the split ring design.  The crankcases were changed to make the breather system function back inside the top cylinder head cover with a vent/drain line coming off of a fitting.

Finally, in 1962, they pinned all three bearings, so the cases were changed again to reflect those modifications. Obviously, the crankshafts and crankcases all have different part numbers and design features which preclude mixing and matching parts from other years.

A good friend in AZ had purchased a couple of less than perfect CB92s and dropped off an engine for me to rebuild. It had suffered a severe piston seizure early in its life and was parked for decades. The engine required a full cleaning and vapor blasting to recover the original finish, plus all the fasteners needed to be re-zinc plated. Fresh pistons and rings were installed back into the original STD bores which were not damaged. All the rocker arms were replaced, but the camshaft appeared to be in serviceable condition. All new valves were installed due to cupping of the seats and valve faces. After a few weeks of running parts back and forth to machine shops, the engine was reassembled and stood waiting for pickup.

As time went on, the VJMC West Coast Rally was announced in Prescott, AZ, so I saved John a 600 mile round trip by dropping off the rebuilt engine at his house. During the interim he pulled another CB92 engine apart for rebuild and had already cleaned and re-plated all the parts. The engine cases had suffered a bizarre damage situation to one of the carburetor cover mounting posts. Apparently one of the mounting screws was seized into the mount and probable use of an impact driver had broken the whole mount off of the case, taking a large chunk of the top case with it.

John sent the case off to Colorado where a skilled welder had managed to re-weld the chunk back into the case, blending the repairs so well that it was almost invisible on the outside.  Good save as that is the half that contains the serial numbers.

When the parts were unpacked, I noticed that the 1960 engine cases had a non-matching 1961 crankshaft installed! Apparently the engine was run like this with the center main bearing free to spin around inside the cases as there was no contact with the crankcase bores.  So, the hunt was on for a new crankshaft with the larger center main bearing. After almost 60 years, finding NOS CB92 parts has become problematical, but within a week, I managed to flush out three different correct crankshafts for sale. Two were out of the country (Thailand and the UK), but the last one came from a stash in WA state, where a long time owner/racer of CB92s had some leftovers buried in his garage.
Had the whole units not been discovered, the Plan B was to buy one of the center main bearings and have a machine shop rebuild the crankshaft with a new main bearing in the middle. These crankshafts are small and difficult to press apart and back together again, so I am glad to have a whole new correct unit to use as a replacement part.

In the meantime, my friend John Stein, in LA, wanted me to revive a 1960 CB92 which he had owned for the past 30 years. I agreed to take on the revival (not restoration) work, so that made three 1960 CB92 bikes or engines that have come to the shop in the past month. That bike showed up dirty and sad looking with a mismatched paint color on the headlight bucket, incorrect tail light, wrong brake cable and other woes, but some restoration work had been done to the hubs and wheels. The bike must have been raced at sometime as there were some crash damage scuffs remaining, a racing rear tire on the back and an all aluminum cylinder block installed.  Plus there were no mufflers on the bike, just a set of loud factory megaphones from the race kit. The bike featured a YB racing seat, as well, plus a tachometer in place of the speedometer.

While all of this was happening, I received a message from a CB92 owner in Los Angeles area who was moving to AZ soon and wanted to sell his “project” 1960 CB92. At the moment, my bike inventory is pretty much at max levels, including a 2013 CB1100, 1988 CBR250R (250 four cylinder), 1988 Hawk NT650 with 1,000 original miles and a newly acquired 1990 NC30 VFR400R. With one 1960 CB92 on the bike stand and another 1960 engine on the work bench, things are in overflow status.

The LA bike was disassembled, had been repainted metallic green, had a chopped off front fender and the kneepad was disintegrating. The engine had 150 cylinders, but the head was still stock 125 parts. The bike had been stored in poor conditions, so there is lots of rust and patina on the parts visible in photos.  The price was at the upper level for what was there, but it had been the seller’s bike since 1964 and he was aware of the value of the bike, even as a parts source. 

Reality check…
After much consideration and parts availability checking, I decided not to pursue the LA CB92 project bike. The 1960 bikes seem to be prone to needing new crankshafts and based upon recent searches, their availability and cost are budget busters. Some of the rare chassis parts are available from a source in Japan, but the seller doesn’t ship to the US, so they would need to be relayed from one of my Japanese based contacts out here to California, increasing costs dramatically.
The current 1960 CB92 engine was held up for a new crankshaft, which arrived recently, but without end bearings or the special thrust washers. I ordered the thrust washers from DSS in the UK, who has to nab them from their partner resource in Holland, so delivery time can be a couple of weeks in the end.  I asked about the spare C92 engine crankshaft still in AZ and they were intact. So, with a little persuasion, the end of the crankshaft was cleaned off and washers shipped out with the set of CA95 cylinders which need to be re-bored before assembly.

Once the cylinders were bored, much of the reassembly went smoothly. The oil filter needed was the shorter version and not serviced. The small 4mm screws tend to get stuck and often the heads are damaged when removal is attempted. I did manage to get them loose and the unit cleaned. Some allen head screws were supplied as replacements, but the thread pitch is slightly different between JIS and ISO so the holes were rethreaded. Eventually, all the bits fell into place and the engine was picked up in late Oct.

Top end tear down…
The 1960 #517 CB92 on the bike lift finally got to the point where I could try the electric starter to spin the engine over in preparation for a startup after 30 years. The starter solenoid just buzzed a little bit, probably due to dirty internal contacts. After a stint on the battery charger, finally the engine spun over with the electric starter, but not very briskly even with the spark plugs removed. A compression check revealed 80 psi on the right cylinder and about 85 psi on the right side, which is way under the suggested 130 psi in the manuals.

The motor was eased down onto the work table and the top end removed. Within the alloy YB racing cylinder block were two STD bore YB pistons, both of which were carboned up on top, but showed little wear on the piston skirts or within the bores. The top ring was removed and checked in the bore for end gap width, but appeared to be on the minimum end of specs.

The head was checked for compression losses and both exhaust valves had odd pits on the valve seat faces, so will be replaced. The camshaft was stamped YB in 2 places. All the cam lobes and rocker arms appeared to be fully serviceable as-is.  Intake valves were de-carboned and re-installed as their seats were still nice and shiny thin rings. Exhaust seats were lightly cleaned and should be a good match for new valves. The ends of the valve stems appeared to be nearly unmarked, so the engine run time must have been minimal on new parts.

The low compression was probably due to the exhaust valves leaking, but the extended valve timing of the camshaft can actually reduce the measured compression readings because of the YB cam timing. The combustion chambers and piston crowns were pretty coked up with burned oil deposits, but the exact cause of excess oil consumption is somewhat mysterious given the condition of the parts inspected so far.

Once some fresh valves are installed, we’ll see what the readings come up to afterwards. The old gaskets were very difficult to remove and more than an hour and a half of labor was expended in just getting the parts cleaned and free of leftover gasket residues. This is always the least pleasant portion of engine rebuilds on vintage Hondas, as far as I am concerned.

Amazingly new correct 205-coded stainless exhaust valves are still available from eBay sellers. The seats were cleaned up and new valves lapped in. New head gasket, sealing rings and a few oil seals were installed and the engine eventually reinstalled. The engine has to go back in with the head first, which is awkward to do with a single jack. I eventually used 2 small floor jacks to get it stuffed back into place. I can do an engine swap on a CB77 in half the time as these little Benly engines.
I managed to track down a new starter solenoid to replace the one whose mounting ears had broken off and were replaced with strap metal. This was another rare part that was found with an eBay seller who had several in stock and took a “best offer” of about 30% less than “retail” for it. CB92 parts like that are probably slow movers in the US, as there were so few bikes sold here and fewer remaining to repair or restore.

Start up and wrap up…
Initially, the bike engine didn’t want to fire up, but after about 15 good kicks, it sputtered to life and kept running with little or no choke, even when cold. The bike stutters just off-idle, then cleans up and pulls through the gears. An open-megaphone CB92 is not something that you want to spend a lot of time on, particularly in a residential neighborhood. I made a couple of mid-day passes up and down the streets, right around home. It pulled past redline going down a long hill, but struggled on the way back up. The 4 speed gearbox has somewhat wide ratios, so it falls off the powerband when you upshift from 2nd to 3rd gears, under load.

I suspect that it needs a larger main jet for pulling high speeds, but also needs a slide with a bigger cutaway or a needle with a fatter taper to help lean out the low end. Despite the hi-dome YB pistons, the D8HA spark plugs screw all the way down and haven’t had their electrodes hammered shut yet.  I think the longer duration YB camshaft profile hurts the bottom end power, causing metering problems for the carburetor, as well as lowering the compression readings at idle.
The clutch was initially “stuck” but leaving it in 3rd gear at 30 mph with the clutch lever pulled in, finally released the pack and the clutch began to work normally. A “best practice” would be to disassemble the clutch pack and clean up the steel plates, but this is to be an occasional bike for running around the block up in LA, so probably isn’t a significant factor in the grand scheme of things.

The task was to get it up and running reliably and make sure that nothing falls off of it during short jaunts. The steering is “twitchy” when changing directions, as if the steering stem is a little bent. There were some signs of at least one lay-down incident, but nothing significant was seen as far as chassis damage. The tires are over 30 years old and the rear one is an old Yokohama road race tire. The front is probably the original OEM 1960 rib tire, so there is a lack of flexibility in the tire combo. The bikes ride like buckboards anyway, with little suspension compliance on either end. A few quick rides did nothing to endear these little Benly buzzers to me and more than in the past. They are an iconic design, but with technology from the 1950s, it leaves a lot to be desired.

Sunday, July 29, 2018

An alluring Honda NT650 Hawk in primo condition…

Honda’s NT650 Hawk GT model was introduced to the US market in 1988. Available in a nice metallic Blue or Silver colors, they looked the part of a great “café racer” style machine, fitted with a 650cc version of the earlier VT500 V-twin powerplant. Added “coolness” features were disc brakes on both wheels, an alloy twin-spar frame and a single-sided swing arm. Weighing in at just over 400 lbs, the bike was a secure handler in a size that fit many riders with a responsive but not overwhelming drive train.

I have owned several of these models over the years, including a very nice red 1990 bike back in 2012. The red bike ran well, but started to overheat due to a failed thermo fan switch, which is a somewhat common problem with these machines. I installed a toggle switch temporarily to control the fan function myself until a new fan switch was secured from Honda. Once that problem was solved, the bike ran well and gathered more than a few miles on SoCal highways during a warm summer.

It is difficult to find really nice Hawk 650s, as many were modified with aftermarket exhaust systems, CBR600 front ends and a host of other “racing” mods to help boost the horsepower to better match the handling of the chassis. I saw a nice original red bike last year, belonging to a long-time friend, but the bike had been off the road for several years and would need a thorough refreshing. His asking price was $4500, as-is, which is kind of top of the market, but it did feature a nice custom seat and a few other upgrades. Ironically, the bike was just posted for sale on eBay auctions with a starting price of $3800, but it failed to gain a bid after a week on the site. It has been relisted at $3200 now.
I wasn’t actively seeking another one, but a recent Craigslist posting popped up late one night that offered a 1988 bike with 1,000 miles for $1,000. The seller was moving soon, had not listed any photos because the bike was buried deep inside his 2 car garage and hadn’t been run in almost 20 years.

I sent a quick message to the seller, who contacted me right away. I spoke with him to get a better picture of what he was offering and guessed that it would probably take about $1,000 worth of work and parts to bring the bike current in the DMV system and completely refresh the whole fuel system, cooling system and add new tires. He set an appointment for me the following day, which I kept promptly. It took both of us to extract the bike from his packed garage. I had brought a portable air compressor to refill the tires, which helped the rolling resistance, but it was clear that the brakes were dragging as well, when the bike was pushed across the driveway.

Apart from a missing tool kit the bike was 100% original. Unfortunately, he had attempted to get the bike running about 10 years ago and discovered that the fuel tank was full of foul-smelling old gas and a good bit of rust inside. He poured some Kreem tank liner inside the tank, probably on top of the old rust and now the liner was peeling off in big chunks. Having been stored deeply inside the garage, it was untouched by damaging sunlight and ozone exposure, so all the paintwork, instruments and controls were nearly perfect.

I was prepared to pay his $1000 for the bike on the spot, as-is, but then he said that “someone from San Clemente had called and offered $1200 for the bike,” sight-unseen. Sure enough, about 10 minutes after I had arrived a young man showed up in a big Chevy PU all excited about seeing the bike. Apparently he already had 2-3 of them, but was looking forward to owning an original one with super low miles. The actual miles on the odometer was 602! Suddenly, it became a bidding war and I eventually prevailed at $1700. The young man headed back to San Clemente and I had to make a quick trip to the bank to pay the extra $700 for the bike.
I was considering how to get the bike into the back of the Tacoma, even using my arched ATV ramp, as the bike was somewhat reluctant to roll very far. Fortunately the owner had a crew of repairman arrive to do some exterior repairs on the house, so I enlisted a couple of them to give the bike a big PUSH and in it went.

\On the way home, I stopped by the local Honda dealership and ordered up $300 worth of parts to use for the fuel and cooling system updates. The fuel tank was going to be the biggest challenge and eventually I spent more than four hours using phosphoric acid, acetone and Evapo-rust products to cleanse the badly corroded tank and rid it of the decaying Kreem coating. The fuel opening is fairly wide, once the gas cap and mounting are removed. Using penlights and a long “grabber” tool, I slowly extracted gobs of loose Kreem coating that was clinging to the bottom of the tank and the various internal venting tubes and baffles inside. The acetone helped to dissolve the Kreem coating eventually and 2 gallons of $25 Evapo-rust dissolved the remaining rusted surfaces. Caswell 2-part epoxy coating was ordered up to seal up the newly cleaned surfaces to prevent any future corrosion issues.

New intake manifolds were ordered and carb float bowl gaskets bought from eBay sellers. The carbs had some very dark and gooey black residues, which were dissolved with degreaser, then the parts went for a bath in my ultrasonic parts cleaner. The stock 135/132 jets were bumped up to 140/135 and the needles raised with tiny shims beneath the needle heads. Hopefully, this enrichment will be sufficient to fuel the engine properly, running on the pump gasoline that we have here in CA laced with 10% alcohol.

The front double piston brake caliper was removed and both pistons pushed out using the original master cylinder for hydraulic pressure. The pistons were gummy and the seal rings were pushing up against the pistons due to 30 years of corrosion and brake fluid degradation. The single-piston rear brake caliper got the same treatment and proper brake functions returned to both wheels.

The cooling system was drained revealing bright green colored coolant and little in the way of corrosion or degradation. The thermostat was removed and inspected. It appeared to be in great shape, so was re-installed. With the carbs off and the cooling system apart, there was sufficient access to the valve train for a valve lash adjustment and inspection of the cams. The valve covers came off easily and everything inside was sparkling clean. The valves needed very minor adjustments and the cams and rockers were oiled up to prevent a dry start for the top end.

A fresh battery was dropped in and all the fluids checked and topped off. The bike fired up quickly off of a remote fuel tank bottle and the engine allowed to run while coolant was observed to warm up and circulate, indicating proper thermostat function.  The engine poured blue smoke out the muffler for about 5 minutes, which diminished slowly down to nothing a few moments later.

With a fully-restored fuel tank and new petcock installed, it was time to button it all up and take it for a ride. While warming up, the bike was pointed out of the way of solid objects in case the clutch had become stuck after sitting for over 10 years. Surprisingly, there was a normal little clunk sound and the bike stood still while in 1st gear as if there was no issue with the clutch whatsoever. 

The first test run was just around the block, followed by another 6 block run while the coolant temperature was monitored. The gauge stayed well into the first 1/3rd range and the bike was running happily along with no apparent distress or leaks. A quick return to home base revealed a loose top radiator mounting bolt with the acorn nut still laying atop the radiator core. Apart from that oversight, the bike seemed to be completely normal, as you might expect for one with just 600 original miles on the odometer.

The bike was revealed to a surprised group of my Sunday breakfast riding buddies.  The breakfast stop suggestion was Potrero, CA which was about 29 miles from our starting spot in Jamul, CA. Bearing in mind that I was running on the bike’s original tires, I rode at a brisk but not neck-breaking pace and the bike rode normally and had decent grip in the corners. The brakes finished self-bleeding the last few air bubbles out of the lines as the ride continued and a continuous smile was painted across my face for the entire ride. The total miles covered, at the end of the day were about 102 and the bike took about 2.5 gallons to top off the tank. These bikes do not have a great fuel range with only 3.2 gallon capacity. According to internet sites, the gas mileage is somewhere in the 45mpg range.

At the moment, I am in somewhat of a dilemma: Keep the “new” old bike or the old “new” bike (2013 CB1100). One of them probably has to go… really tough decision!
Bill Silver    aka “ MrHonda”

Specifications from June 1988 Cycle World Test (unless noted)
List price: $3995
Weight tank empty: 393 lb
Weight tank full: 412 lb
Weight distribution tank empty: 46.9f/53.1r
Weight distribution tank full: 47.1f/52.9r
Fuel Capacity: 2.9 gal (3.2)*
Wheelbase: 56.3" (56.0" 1422mm*)
Rake/trail: 28.0 deg/4.7" (27.0 deg/4.4"*)
Handlebar width: 26.6"
Seat height: 30.4"
Ground clearance: 6.1"
GVWR: 745 lb
Load capacity (tank full): 333 lb
Electrical power: 300w @ 5000 rpm
Battery: 12v, 8ah
Headlight: 60/55 halogen
Engine: 52 deg v-twin
Bore & stroke: 79x66mm
Displacement: 647cc
Compression ratio: 9.4:1
Valve train: sohc, 3 valves/cylinder, threaded adjusters
Carburetion: 2x36.5mm Keihin CV
Oil capacity: 2.9 qt
Sprocket sizes: 15/44
Gear ratios, overall:1
1st 13.29 (12.78*) (14.38**)
2nd 9.73 (8.7*) (9.78**)
3rd 7.76 (6.71*) (7.53**)
4th 6.41 (5.42*) (6.1**)
5th 5.55 (4.47*) (5.02**)
Front suspension: Showa non-adjustable 41mm w/ 5.5" travel
Rear suspension: Showa adjustable pre-load w/ 4.7" travel
Front wheel: 2.5x17"
Rear wheel: 4.5x17"
Front tire: 110/80-17
Rear tire: 150/70-17
Front brake rotor: 12.4" (315mm)
Rear brake rotor: 9.4" (240mm)
1/4 mile: 12.7 sec @ 102.97 mph (12.89 sec @ 99.87 mph*)
0-60mph: 4.0 sec (3.95 sec*)
Measured top speed: 115 mph
Braking distance from 60 mph: 116' (121'*)

Thursday, June 14, 2018

Back in the saddle with 250-305s again…

After running through a handful of interesting JDM bike and thinning out my little herd, the inevitable return of 250-305s began in the past few weeks.

Chapter 1:  CB77 for sale... not bought
A friend alerted me to a CL posting for a 1965-ish CB77 for sale at $1100 asking price. Photos showed oversized tires on both ends, missing fenders, an a/m seat and the wrong mufflers, just to start with. The bike was 50 miles away, but I already had some business in the area so it wasn’t too much trouble to cruise over and have a look. The seller was a nice mid-aged man who had put together a café CB550 project and had gotten the CB77 from a friend who first wanted to make a custom bike out of it, then decided to sell it as-is. Photos did it too much credit as the chassis had been modified around the forward seat mounts and the black chassis had a red front end attached. The ignition switch and the fork lock numbers didn’t match, so I assumed that the front end was replaced from another bike.
It wasn’t running due to dead battery, stuck carb slides and the usual faults found on a long-abandoned project bike. It needed a chain guard and a new wiring harness, which I happened to have left in my parts stock, but the more I considered it the more I kept remembering all the CB77s that I spent endless hours on to get running, then wind up selling them for what I had spent on parts and services. Somehow I found the strength to say NO, even to a reduced price of $800. I was proud of myself for walking away from another “project” that would have no financial reward at the end, whatsoever.

Chapter 2: Domestic CL72 engine rebuild
A few months ago, my longtime friend J. Braun inquired as to whether I would “rebuild my CL72 engine,” which I assumed would be just doing the engine, brought down in a box. After a long, long haul from UT, he arrived with a whole CL72 Scrambler in the back of the truck! After some discussion, I offered to remove the engine while he went back to his overnight lodgings to check in, then he would come back to pick up the chassis and haul it back home the next day. I had the engine out in the first hour and the top end removed from the “stuck” engine by the end of the 2nd hour. We went to a nice Italian restaurant for dinner, in celebration of my 70th birthday, then he brought me back home and we loaded the chassis into the truck.

The following day, I spent another 2 more hours carefully disassembling the very dirty and corroded engine which happened to be a domestic Type 2 (360 firing crankshaft) model. Fortunately, the crankshaft seemed to be in great shape, so the rest of the work will be extensive cleaning, prepping a spare set of cylinders for use and rounding up the required expendables like seals, gaskets, primary chain, camchain, bushings and kickstarter pawl bits.

The pistons removed were already .25 oversized, but were stuck in their bores due to water going down one intake side, through the carburetor and into the cylinder. The bike was last ridden in the early 1990s and then left in a corner of a shop for the next 25+ years. J remembers riding the bike, but seemed unaware that it was a Type 2 powerplant. The bike did have a kph speedometer and the remnants of the factory turn signal switch on the right side handlebar end. Most of the winker system parts were long-gone, but the original heel-toe shifter remained. These bikes came with non-folding driver footpegs and among the parts were 2 sets of NOS 273-000 footpegs to match the application.
It seems to take a couple of weeks to get all the parts cleaned properly and replacements lined up for the reassembly process. Overall, the engine components are all usable, without any of usual broken fins and similar damage often found in a bike like this which was being used as designed… as an on-road and off road machine.

As an unexpected bonus, J brought down 6 boxes of mostly NOS Honda parts for Scramblers and Super Hawks. There were a couple dozen of those little standup envelopes containing many small parts needed to rebuild these engines. There was spare ignition switches, unused and used, plus CL72 air filters, many sets of levers, NOS CB77 black cables and a variety of interesting bits. A good bit of it will go into the engine rebuild, with the rest offered on FB forums or eBay if all else fails.

Chapter 3: Return of the 1962 CB77 #25
It was old-home week as a revived 1962 CB77 with frame number 25 returned here for some troubleshooting and maintenance updates. I had received the bike as a rusty, corroded hulk with seized engine and lots of damage from moisture due to its long-term storage near the ocean, inside a shipping container. I only had 30 days to complete the revival, as I was scheduled for knee replacement surgery on day 31. I had written the whole story for my former internet host, the “” site which suddenly went dark a few years back. Fortunately, I had all the original stories saved on my computer and made a backup copy from the website before they closed.
The repairs were massive, despite the bike only having 2300 original miles showing on the speedometer. Even the tires and tubes were original OHTSU branded from the factory and while in terrible condition it was worthy of a quick rebuild and documentation of what exactly was and wasn’t changed on the first day of production for the 1962 models.

The bike was sold to a LA enthusiast who is active in the LA region of vintage Japanese motorcycles. With little break-in time, he rode the bike all the way out to their annual Death Valley desert run, which was some 350 miles away. The bike survived the trip and actually made another run the following year. With changing priorities, the owner decided to put the bike up for sale, but the Super Hawk began a series of misbehaviors, including dropping the left side cylinder intermittently. To help regain reliable ignition functions, a new electronic ignition system from Charlie’s Place was purchased and installed. The way the system is designed, there are some limitations as to the positioning of the control module which prevented installation of the point cover, if moved much beyond the center of the adjustment slot. The trigger wheel, which attaches to the end of the points cam can be installed in a 90 degree spread of options, so for successful installation the trigger wheel must be set, tested for timing function and then adjusted again when the timing was excessively advanced or retarded.

The instructions were a bit vague and there was a lot of trial and error until the full function was understood and the final adjustments locked in place. With the ignition setup correctly, the bike fired up immediately. I had checked the compression and idle jets for being clear, prior to finalizing the ignition timing. The bike warmed up quickly and I decided to take it for one last test run before it disappeared from my life forever. I barely got a ½ mile away and noticed that the clutch was slipping under anything more than half throttle. Coming back up the test hill nearby, the clutch was slipping and sliding all the way up, unless the throttle was modulated carefully. Then, there were the oil leak issues, which had been mentioned previously. A quick look showed oil coming out of the outer oil filter cover, down the tachometer cable and the shift shaft seal. All the next work was to be on the left side of the engine, so I had hopes that most of the leaks could be solved with replacements of o-rings and seals.

So, the unplanned services now included a clutch inspection, which requires draining the oil (good thing as it was needed anyway) and removal of the left side clutch cover to access the internals. Once the cover was removed, everything inside still looked pretty clean and shiny inside. The clutch was the original 6 plate version, to which I added some 323 coded (CB500) clutch springs which normally prevent clutch slippage. All the plates seemed pretty good still, so I bumped the springs up to some 374 code parts, which are for the CB550 and are a big longer than the CB500 versions. Before the clutch cover was reinstalled we checked for clutch lever pull effort, which seemed to still be reasonable to both of us.

I replaced the outer oil filter covers two o-rings, installed a new shift shaft seal and rechecked the cover for any high spots which can cause common gasket leaks in these engines. With the engine buttoned up and new Honda GN4 oil added, the bike was tested once again and this time the clutch function was normal, but the oil filter cover still had a bit of a weep even with new o-rings! I suggested that he make a thin paper gasket and seal the cover that way, which seems to be the only other way to contain the leak. It is an uncommon problem in my experience, however this early engine had the “small hole” cover and filter cover, which was revised later with a larger access hole and an extra o-ring in the clutch cover case to help seal it more effectively.

Starting at his 9am arrival time, we worked continuously until well past 1pm on Memorial Day. All the work paid off in getting the bike up and running, plus curing most of the unmentioned issues with the clutch and oil sealing problems. The bike is a solid example of Honda’s earliest CB77 efforts and an interesting transition bike from the 1961 year to some of the changes in the 1962 models. Looking at parts books, there were more changes to come as the 1962s continued in production, but this was a true example of what happened as Honda ramped up into the second year of Super Hawk sales.

It is bittersweet to revisit a bike that you built a few years before and then had to hand off to another CB77 enthusiast. Hopefully, the next owner will be inclined to spend some money and time on re-chroming and polishing the corroded bits that remain and give it a place of honor in their garage and out on the roads!
Bill Silver
aka MrHonda

Sunday, May 20, 2018

Lucky to be here for #70

Starting my 7th decade on Thursday May 24, I have to stop and be grateful for all the blessings in my life of family and many motorcycle friends around the world.

I have had three different motorcycle crashes that could have taken me out for good, but somehow I survived them all and still enjoy riding my bikes regularly. Current stable includes the 1988 CBR250R, a 2013 PCX150 and a 2013 CB1100. There is a possibility of another CB77 coming my way next week, but that’s not for sure.

I lost track of all the bikes and cars that I have owned/sold in the past 50 years, but I think it has ranged upwards towards 400, starting with my 1967 CL90 Scrambler, the first bike I ever owned. Since then the bike list ranged from a 1954 F Cub to a few CBXs with lots of 250-305s in the mix of all types. In the last year I have had a handful of JDM bikes that I never imagined owning and riding, including a 1997 Dream 50 street bike, 1968 domestic CB350 (with CB77 style fuel tank) and a pair of CBR250R bikes with 18k redlines. It is now just possible to sample more JDM models here in the US due to the 25 year old rule kicking in favoring some of the unusual Japanese bikes and cars which we could never experience until now.

I missed the opportunity to have a long-term "life partner" who shared my enthusiasm for motorcycles, but at least they tolerated them while we were together. I am fortunate to be in a relationship now with a woman who grew up riding Honda CB160s and CB175s (without a helmet). She "gets" the attraction of motorcycles and appreciates that I am a key figure in the world of vintage Honda motorcycles. That is a rare quality in women in my experience and I am grateful for that now.

It is gratifying to see more women become involved in rides and motorcycles in the past few years. Motorcycle ownership and riding is waning somewhat according to the latest news reports. Current generations of eligible riders have delayed even getting a driver’s license at all as other transportation options have become available, like ride-sharing and an emphasis on bicycles. 

The face of motorcycling, as a whole, is changing with the latest technologies in electric cars and motorcycles. It is hard to imagine riding motorcycles which basically are completely silent apart from the gear whirring of the electric powertrains. Future generations will miss out on the roar of the Honda CBX six’s wailing exhaust systems or the mechanical commotion of a small 250cc four cylinder bike with a 18-19k redline as it peaks past what seems to be impossible revolutions for an internal combustion engine.

As we look to the future, however, the continued burning of fossil fuels appears to still have consequences to the global environment. Banning diesel and gas powered vehicles may well help stem the tide of carbon dioxide that filters upwards into our precious atmosphere which has caused the conditions of global warming or at least been a contributor to it for the past 100 years. How different the world will be in another 25 or 50 years, assuming that we are able to reverse some of the climate changes in some way or other.

For people of my generation, we have watched an amazing transformation of automotive and motorcycle technology starting with ancient and ineffective combustion engines that would ping and detonate with an 8.0:1 compression because the fuels were not sufficient to support anything higher than that. Today we have street bikes with 150-200+ horsepower, still running on premium alcohol injected fuels, despite compression ratios in the 12 to 13:1 range.

My first “real car” was a 1956 Ford 4-door with a 272 cu in engine, three speed stick shift on the column and a 2bbl carburetor. I think that it usually got about 14 mpg perhaps, but gasoline was $.25 a gallon back then, so fuel costs were not a particularly big concern. Disc brakes were unheard of back then, apart from being on exotic racing cars or airplanes. Four troublesome drum brakes were the only option back in the 1950s; and you had to keep an eye on them as those asbestos brake shoes wore out quickly hauling a couple of tons of steel down to a halt.

Honda Super Hawks, with their 200mm dual leading shoe brakes, were the epitome of motorcycle brakes in the 1960s. Those brakes were often pirated from dead bikes to be used on roadracers or even other street bikes whose brakes were poorly chosen for their stopping tasks. Despite all the hoopla surrounding the disc brakes on the CB750s, their single piston brake calipers really didn’t do a decent job of slowing down a 500+ lb street bike from high speeds. Even worse, the first generation CBX models had similarly insufficient braking for a 600 lb street machine with 130mph speed potential.

Today, we have ABS brakes available on even the smallest street bikes and even pedestrian scooters. Brake calipers have at least 2 pistons each and extreme cases all the way to 6 piston stoppers. Finally, tire technology has had to rise to the occasion in order to cope with the tremendous braking power available on today’s models.

It is hard to find a motorcycle shop now that has mechanics who understand the functions of carburetors and point/condenser ignition systems. Electronic fuel injection has recently been available for even 50 cc model machines in many markets. Troubleshooting and re-jetting carburetors has become a lost art for many mechanics of this generation.

In the past 25+ years, I have published helpful books and electronic media information to help carry what I have learned to future generations. I originally typed my first books on a word processor machine and then printed out the masters to take to a copy shop for reprinting into paper books for sale. That process worked well for about 10 years before I was able to get my hands on computers with some real fire power that allowed sharing of more and more information to more and more people in the world. Now I can offer thousands of pages of information via a download to just about anywhere in the world at a moment’s notice. Yes, the world has changed a LOT in the past 70 years…

I appreciate all the positive feedback from readers through the years. I continue to learn more new facts and nuances about the 250-305s and plow that information back into my offerings. I welcome questions about the vintage Honda models and can usually offer an answer from my experience or will find out what an answer might be from friends and other enthusiasts.
So, to all my readers: Thanks for the memories and support, in our combined search for the answers to our technical questions and discovering the history of these amazing vintage bikes.

Bill Silver 
aka MrHonda

Tuesday, May 8, 2018

Time flies, whether you are having fun or not…

Dear readers,

My apologies for failing to update this blog recently. I have had quite a lot going on wrangling my 1997 Dream 50 street bike and the Rickman CR750 project bike, of late. In addition there are the transient repair jobs that come in and out of the shop that tax my patience and shop space at times, too.

The little Dream 50 street bike arrived a few months ago, packed with a built from scratch 89cc race motor, featuring a dry clutch conversion, race head and cams, HRC crankshaft and 5 speed transmission. The head was ported and a monster 26mm Keihin CR carburetor adapted to the cylinder head. The engine was built with a new set of cases and all fasteners, which caused a problem with registering the bike in CA. California requires engine numbers for the titles and the new engine had none.

The bike did come with the original 5.5 horsepower stock engine, which was restricted by various methods. The cylinder head had a small 16mm port leading to undersized valves. The carburetor was a 16mm Keihin, tied to the stock air box. Honda’s CDI ignition system was married to a transmission switch that sensed when the bike was in 4th or 5th gear. The spark timing was limited in the top two gears to prevent the bike from exceeding 36mph (60kph) speed limit which is imposed upon 50cc motorcycles in Japan. Additionally, the front drive sprocket has only 12 teeth, which is the same as a Z50 mini-trail model. A little digging around on eBay turned up 13t and 14t options, however.
It is sad that a bike with such flashy good looks and disc brakes on both wheels is so restricted, but of course there are ways around those issues, which have been shared on the internet over the past 20 years. One of the gear indicator leads had been rewired with small little resistors between the wires to over-ride the speed limiter functions in 4th and 5th gears.

The stock cams top out the power output at about 10,500 rpms, despite a 13,500 rpm redline on the tachometer. An XR75 20mm carburetor was acquired from an eBay seller, which is a bolt-on for this bike. Jetting wound up in the #85 range vs. #75 for the stock 16mm carburetor. With all else basically in a stock configuration, the bike will tach out to 13k in 4th gear burying the speedometer needle to approximately 60 mph on a long downhill run with a 14t front sprocket.

When the stock engine was reinstalled to get the registration accomplished, the 89cc big bore kit was installed on the engine, using stock cams and the 20mm carburetor. While displacement increases are always helpful on small-bore engines like this, the compression ratio was 11.6:1 and kicking it over was quite a chore, given that the kickstarter system was designed for a 50cc piston at 10:1 compression. Eventually, the bike was reassembled back to stock 50cc size, still keeping the larger carb in place. So far the engine has been out of the bike three times!

Getting a JDM Honda motorcycle registered in CA isn’t always easy, however the combination of having an Indiana title and the fact that the bike was less than 49cc allowed an over-ride in the CA registration system and a fresh CA title and license plate were issued to me for the little tiddler.

The bike was offered up as a package: stock bike along with the race motor and a lot of rare spares on eBay. The auction page count was nearly 2,000 with over 100 watchers, but failed to rise above $6700 at the end. After that, just the race motor and other racing parts were offered as a separate package, which drew several hundred page hits and over a dozen watchers, but no bids at the end.

The bike may wind up in a trade situation for a 1964 CB92 Benly Super Sport deal soon, but that hasn’t been finalized. As beautiful as the little Dream 50 is, its overall usefulness is limited for the type of riding that I hoped to be able to use it for, locally. Perhaps my expectations were overly optimistic for a 50cc bike that I outweigh by 10 pounds. I have fond memories of owning a 1970 SS50 which was brought in from Japan when I was in the USAF. That bike was always capable of 60mph in dead stock form. It is funny that with the passing of time and the improvements in technology haven’t yielded a faster machine than that little 2-valve horizontal single in the SS50, dating back 45 years.

Monday, March 12, 2018

Reviving more dead and dying bikes…

In the past few weeks, another parade of lifeless motorcycles has come through the shop and each one had various unique challenges and surprises, in some cases.

This bike has been a thorn in the side of the owner and me for a year or so. The bike was only used in the summer months, so sat for long periods with a half-full tank of alcohol gas and a weak battery and charging system. After a new battery was installed, it didn’t seem to be getting a good charge, so a new solid-state reg/rectifier was tried out but was either a defective unit or just not the right type for that old school design. Putting the old parts back in carefully seemed to have awakened something and then the bike ran well for a few weeks. Then there were misfiring problems that lead to a house-call where I discovered a loose ignition wire connection that seemed to have solved the problem. I didn’t test ride the bike, though and a few weeks later the owner complained that the bike would be hard to start, run awhile and then the battery would seem to discharge again.

The bike was brought to me this time and I dissected the charging system once again, but found little to fault. I quick test ride left me stranded about 6 blocks from home, though. I walked the bike back to the house and checked for fuel to the carbs, as the battery got run down from trying to restart it after it died down the street. It turned out that the owner had drained the old gas/rust/water out and put 1 gallon of gas back in the tank, without telling me. When the petcock was removed the reserve function was plugged up so it wasn’t supplying gasoline to the carburetors. Arrrgh!

The petcock was cleaned, tank rinsed out again and 3 gallons added to the tank. Once the battery was re-charged the bike fired up sluggishly, but did run okay once it was warmed up for a few minutes. Using carb spray, some air leaks at the manifold/cylinder head junction were discovered. The manifolds didn’t appear to have failed, but it was decided to change both the o-rings and manifolds as long as it was all apart. The battery was again charged up to where it was holding about 12.5 volts at rest.

Changing out the manifold o-rings and manifold connectors was not a particularly fun task with the carbs and airbox in place, but using some brute force was eventually accomplished. Using full choke, a cold engine start was initiated and the bike barked to life much more quickly than before. The lack of air leaks and subsequent resetting of the idle mixture screws brought the 29k mile engine to life at all engine speeds. When the battery started out at 12.75v in the beginning, it remained at that voltage level after a 15 minute test ride. These bikes have instant ON headlights, so the battery drain starts as soon as the switch is turned ON.

Speaking of ignition switches… the ignition switch base cover was not securing the switch base contacts to the rest of the switch assembly. Pulling the headlight loose from the fork ears gave access to the switch mounting bolts and the whole assembly was unplugged from the harness. The aged harness connector was getting brittle, but still had enough strength to hold the switch contact connector securely. It appeared that someone had tried to replace the switch base cover previously, but the slots where the cover snaps into the switch base were still plugged up with remnants of the original cover tabs. Clearing the tab holes allowed a new cover to engage the switch housing base correctly and securely.

When Honda started putting the ignition switches up in the middle of the instrument cluster, problems have arisen in the older, hi-miles machines where the constant push-pull of the harness wiring as the handlebars are turned back and forth causes the switch base and cover to work loose. When the connector separates just a little bit from the switch base, power is interrupted or lost altogether.

The combination of a loose ignition switch base, lack of fuel, weakened battery from excessive cranking caused a whole cascade of problems that the owner was experiencing. After chasing out the gremlins and getting the bike running properly, attention was made to the rest of the bike which had run out of rear brake adjustment threads due to worn shoes. Replacements were ordered and installed, so now the bike’s owner has a better chance of riding a bike that operates correctly and is safe to ride for the summer.

Two more dead ones…

A good friend from Los Angeles brought down a long-dead 1967 Honda 305 Scrambler and a 1982 Honda Z50R Mini-Trail bike for revival. John had owned the bike for more than 25 years, buying it for its overall originality (some restoration work was done) and had never really ridden it. The Mini-Trail 50 was destined for his grandkids once it was brought back to life again.

The 305s are my specialty, so generally no surprises there, but not many Z50Rs have come my way in the past 30 years. Basically, they are about as elemental as you can imagine, but this one had me scratching my head for more than a few hours as repairs were made and tested.

1982 Z50R

Most of the little 50-70cc Honda singles have a simple magneto-ignition, a compact OHV cylinder head and tiny single carburetor, running an automatic clutch to make the package operate under the normally grueling conditions that are the life for Mini-Trail motorcycles. I was given a tune-up kit with the Z50R, consisting of a new spark plug, ignition points and a condenser. Removing the flywheel was the first order of business and that uncovered a magneto that had either been run uncovered in the dirt or just stored in a very dusty and moist environment for many years.

The inside of the flywheel, where magnets are located was coated with dust/rust which made the transfer of electrical energy impossible. The magneto base was similarly coated with dirt on every surface. The condenser wires are soldered onto the top of the unit, so you have to unsolder the old one first. Transferring the wire connections can be tricky if you have a cold solder joint or the wire ends are not tinned properly. The tune-up kit was an aftermarket brand whose parts fit the engine, but were really not all of the quality of OEM components.

Once the magneto base was cleaned and all components installed the flywheel was fitted for testing. Unfortunately, there were no signs of spark initially, so the flywheel was again removed. A closer look showed that the primary ignition coil base has rusted ends, which again work as an insulator against the effects of the flywheel magnets. Once a careful cleaning of the coil posts was completed the ignition finally showed signs of life giving off a nice little blue arc across the spark plug gap.

The carburetor was removed and found to be remarkably clean, however the pressed-in pilot jet appeared to be blocking fuel flow due to residue inside the .014” hole. The jet was twisted, pulled and finally removed for inspection and cleaning. Tiny tapered reamers were used to clear the passage, but when the jet was pressed back into the carb body, the fuel flow remained blocked.

With the jet removed once again, it appeared that the feed hole in the carburetor throat was drilled slightly off center, so that the blunt end of the jet was blocking fuel delivery. The end of the jet was beveled a little, but flow problem persisted to the point where the engine would run, but idle mixture flow was uneven, causing the spark plug to fuel foul leaving black soot on the electrode end. The engine would either not idle or would suddenly speed up to a fast idle. Mixture screw adjustments had little effect on the condition and finally a new carburetor purchase was made to eliminate what seemed to be the running problem.

The fuel tank was initially viewed as “amazingly clean” at first glance down the filler hole. When the tank was removed and the petcock unscrewed from the fitting, a little rain of rust particles poured out of the outlet. It appeared that some water/moisture had settled down at the bottom of the fuel tank, causing rust flaking to occur. It never was enough to work its way up towards the opening so at first glance, it appeared to be a clean tank. Rust bits were knocked loose and a new petcock installed with a screen to prevent rust from coming through the fuel lines and carburetor float valve.

These little engines often suffer from little or no maintenance, so the typical reason for them to be discarded is that no one has ever adjusted the valve clearances. The clearance is only .002” so over time the valves sink slowly into the seats and the result is compression loss, with hard starting and poor performance issues. Adjusting the valves often brings them back to life without a lot of extra work involved.

This bike was showing a bit of oil smoke in the exhaust, so the cylinder head was removed (requires front tire removal!) and the valve stem seals replaced and valves cleaned of old carbon deposits. In the end, the compression readings were over 150 psi, which is great for these small engines. With a new carb, correct ignition timing and fully functioning cylinder head, the bike now starts and runs well.

1967 CL77

After an initial visual inspection, a big parts list was initiated including new air filters/tubes, spark plugs, carb repair parts, new cables, replacement hardware for the missing brake light switch and centerstand hardware to replace the undersized stand pivot bolts and a very long coiled spring that wrapped around the swing arm. The correct centerstand hardware consists of two special pivot bolts, a spring hook and short coil spring. The brake light switch stopper mount had been repaired using a small flat washer, tack welded into place. The switch bracket is welded onto the frame and this one was bent up at about 10 degrees from normal. While changing the rear brake cable, the brake arm was slow to move indicating that the brake cam lubrication was gone and corrosion was taking its place.

So, the rear wheel was removed to service the brake cam problem, only to find that one of the brake return springs had a broken end, so was just hanging inside the hub ready to fall into the drum at any time. New springs were ordered and the brake cam removed, cleaned and lubricated for normal function. The front wheel will need the same service as the brake cable pulling the brake arm is mostly non-responsive. The brake cams were sticking and the brake linkage had been installed backwards. These are the kinds of things that you must expect on a 50 year-old bike that has been stored for more than half of its life.

With overhauled carbs, petcock and new air filter assemblies, the bike was nearly ready to start back up. Fortunately, this gas tank WAS REALLY CLEAN inside, which is nearly unheard of given its age and storage situation. Compression checks were a bit under specs at about 120-130 psi, but that is enough to make them start and run. Often there is a thin layer of carbon or rust on the valve heads and seats which prevent a positive valve seal in initial running. Once the bike began to run, the engine sounds improved in the quality of exhaust tone and I suspect that valve sealing will improve with time and miles.

The ignition timing was somewhat close enough to run, but dynamic testing showed an over-advance condition on the left cylinder. The bike idled low enough to establish running idle timing before the spark advancer kicks in and kicks the spark timing up to the 45 degree (II) mark. With some 12k miles on perhaps the original engine, the internals are bound to be worn to some degree. The central camsprocket carries the spark advancer plate, weights and return springs, which are subject to wear and loosening of the rivets that hold the whole assembly together at those mileage markers. 

The spark timing was established correctly, but the engine tends to want to rev up and then return rather slowly. Often, this is due to the carb slides sticking or throttle cable routing problems. New o-rings were installed on the carburetor flanges and insulators, so the manifold air leaks should not be an issue which could contribute to uneven throttle response. For reasons unknown, the main jets installed on the carbs were #120 vs. normal #130 mains. With today’s alcohol-based fuels, even larger jets might be required.

The handlebar upper clamp was cracked in the center, which was a first for me to encounter. A new OEM part was ordered from eBay sellers and was to be installed when a rather shocking discovery was revealed beneath the cracked part. What appeared to be OEM Honda CL77 Scrambler handlebars are probably those made for a CL350-450 model, which have a wraparound reinforcement in the center section. The handlebar clamp has no provisions for this raised section, so it was no wonder that the part cracked when the bolts were tightened down.

Instead of replacing the bars, the ends of the existing clamp were cut off and made into individual pieces which secure the handlebars and clear the raised center section of the installed unit. This is a bike that is FULL of surprises. While much of it appears to be original, it has obviously re-plated wheel rims and a few other chrome pieces. 

This bike is one of the later 1967 models, which feature chromed front and rear fenders, plus the oval-shaped tail light assembly.  A replacement lens was purchased to repair a broken stock lens on the bike. Other repair issues include a stripped out frame bolt hole which is used to secure the exhaust system to the chassis via the long, special 10mm head mounting bolt. Honda Scramblers are well-known to vibrate and loosen various parts along the entire motorcycle, so this was not a big surprise, but the repair of a shallow blind threaded hole is challenging.

There are well over one-thousand parts on a vintage Honda twin and each one has a purpose and function. This is another one of those “surprise” bikes which had been partially repaired/restored by someone who was certainly creative, but not one who went by the book on ordering and replacing damaged parts with OEM equipment. These are the challenges that many mechanics and owners face as they try to revive 50+ year old vintage Hondas. One must be patient and diligent in looking at all the parts and pieces during the rejuvenation process.

Bill Silver  aka MrHonda