Tuesday, May 3, 2022

Knock, knock! Who’s there? CL160.. uh, oh...

The cast of characters:

Owner from N. Cal (600 miles away)

Bike: 1966 CL160, bought from Craigslist with unknown history

Factory photo courtesy of AHMC.

Referral: Tim McDowell (MD)

Stated problem: Won’t idle down properly.

Troubleshooter: MrHonda, Spring Valley, CA


So, I get this call from Tim saying that he referred a caller to me about a CL160 with carb problems. Okay, I don’t work on 160s as a regular thing, but how hard could it be????


The owner, named Pete, drops off the bike from the back of his pickup and wants to hang out as I try to figure out just what the issues are with his machine. All he knows is that when it starts it up, it revs to the moon and he can’t control it even with idle screws all the way out.


First, the tank and seat come off and compression checks are made. Cylinders are showing 180/165 psi. The spark plugs are fuel/oil-fouled black. The spark advancer was replaced previously, but the ignition timing is about 10 degrees retarded. Timing reset and a separate fuel bottle is hooked to the carbs. Carb bowls were already pulled off for inspection and gunky gasoline discarded. Fuel bottle connected to carbs, engine kicked over, but won’t start. Check spark and clean plugs with brake cleaner. Spark to both plugs, but still won’t start up. Check right side bowl and it is empty. Check float valve, but it is clean and we determine that the fuel bottle isn’t high enough to feed the carbs. Reposition fuel bottle and engine starts up and immediately revs to a million rpms.


We know that spark timing is okay, carbs are getting fuel and slides are now backed off enough to allow an uneven idle, but the exhaust is pumping out blue smoke worse than any Kawasaki Triple on pre-mix. Holding the idle up to medium revs to clear the exhaust system of un-burned fuel sand carbon for a few minutes doesn’t help clear the smoke. It’s obvious that pistons/rings are not doing their job and the engine will have to come out for repairs. On top of that, there is an irregular knocking noise coming from somewhere deep inside the engine.


Pete watches for a while and then heads back up to LA where he’s staying with family for a few days. Engine removal continues and once it drops onto the dolly, I wheel it back to the workshop for a quick tear-down of the top end. Nine fasteners hold the head down to the cylinders and the top cover is off. Cam and rockers all seem okay, so camchain master link is found and disconnected. I put pieces of 22 gaelectrical wire through the ends of the chain with a knot tied in one end of the wire to keep track of the camchain.


The head then comes off and I am surprised to see one shiny new piston installed in one side and a used one in the other. ????? I remove the pistons from the rods and check piston clearances and end gaps on the rings, all of which seem to be in specs. The cylinder bores are glazed and looking at each piston ring, I find that several are installed upside down, including the scraper ring which pulls oil off the cylinder walls and sheds it into the crankcase. The rings are tiny and markings barely seen without magnification aides. The top one just has a T mark, while the second one is marked with a T2 (or R2) as they are Riken ring sets. The one-piece oil ring does have a T mark as well.

I hone the cylinders, reset the rings and reassemble the engine once again. Fortunately, I had a full engine gasket kit on hand to do all of this work on the spot. My floor jack is leaking oil when I jack the engine back into the chassis, so everything is getting messy. Finally all the bolts are installed and once the carbs and exhaust are mounted up, the bike is fired up again. The engine smokes again for a few minutes but it is much reduced and begins to clear fairly quickly. I can hear the engine is running rich off-idle and had noted that Keyster kit parts were installed in the carbs. These kits are notorious for being out of tolerances for correct jetting and cause all kinds of tuning problems. Despite the engine running much better already, I drop the needles all the way down to clear the rich condition and the engine responds as desired. Still the knocking sounds continue, so the next step is to pull the clutch cover and check for something loose or broken inside.

The oil is drained and is clouded with tiny metallic specks but no big chunks so far. I removed the first drain plug I see and only a few spoonfuls of oil come out. ???? Then I remember that these engines have two drain plugs! The forward one is 19mm not 17mm and turns out to be a self-tapping plug. Lots of oil pours out of that drain plug, but is laced with metal flakes.


The clutch comes apart only after removing the crankshaft mounted oil filter outer cover, then the inner locking nut. Then one of the two off-set drive gears comes off. The clutch pack comes out as a block after the springs are removed. The clutch is stuck solidly, so obviously this engine has not run or run well for a long time. I pry the plates apart and then bend back the locking tabs on the oil pump which comes off with the clutch outer hub as the pump is driven off an eccentric on the back of the clutch outer.


The pump screen has two little support feet which are all bent backwards because someone installed the screen in reverse of normal. There is a little backlash on the clutch basket even with offset gears that are supposed to neutralize the play. The whole clutch basket has some end play that could cause some of the knocking sounds, but nothing is conclusive. With the clutch plates untangled from each other, the whole assembly is reinstalled and a new cover gasket placed in between the cover and crankcase. 1.2 liters of Honda GN4 10-30 oil fills the crankcase up to the fill mark on the dipstick and the engine is fired up again. Now the clutch is working, but the knocking sounds continue unabated. I’m running out of ideas… I go to the rotor side of the crankshaft and remove the bolt and use my 16mm rotor bolt tool to pop the rotor off the crankshaft end. I put the dyno cover back on and start the engine… same noise.

I pull the cover back off and grab the end of the crankshaft and pull/push. There is noticeable end play in the crankshaft assembly, which must be the source of the noises. As the engine is revved up into the middle ranges, the sounds subside and the engine sounds normal until you drop it back to idle again.

It is what it is, so I button it all up and install the air filters, side covers, tank and seat for a test ride down the street. About the time I am putting it back together, I look through a box of spare bits and find a container with all of the OEM carb parts, including the correct needles! Swap in the needles and the bike is running sweetly now. The idle adjustments continued to be very touchy and I swapped in a set of shorter idle speed screws, so they catch more threads to stay in place and are more adjustable.

The bike is starting with one kick and idles down normally, but one hundred yards down the street and a new noise comes to my attention. The growling sounds of the speedometer bushings are making themselves known and the needle is showing 70 mph while I am trolling along in 2nd gear at mid-throttle. One more issue to present to the owner. I suggest that either he finds a really good crankshaft, but he realizes that replacing it is a full engine tear-down that will take a good 6 hours to perform. Or maybe someone has a low-miles engine that can be swapped into the chassis instead.

While Pete was back in LA, he was following up on a CL77 bike for sale and winds up buying it. The bike has not run for many years, but is a complete 1967 Candy Orange model with chrome fenders. The serial numbers are above 68,000 so it must have been one of the last ones to come off the line.

So, guess what? Pete comes down with the CL77, drops it off, picks up the CL160 and heads back to LA, then home to N. Cal. He plans on returning in a month and in the meantime I am gathering up parts and scheduling in work to get the bike running, change the tires and make it ready to ride once again.

At the moment, I have 7 motorcycles on the property. Three CB77s which are mine, the CL77, a SS175 Harley AMF 2-stroke street bike with dead ignition, a CB500 in for carb work and oil leaks and finally my 2020 Royal Enfield, which I ride on Sundays with the Jamuligans (my buddy’s name for our little group). So, again, no good deed goes unpunished. I keep trying to clear my backlog of parts and repair jobs, but the volume is continuing to grow instead of shrinking. This is going to have to stop one of these days…


Bill Silver

aka MrHonda

www.vintagehonda.com

5/2022

Saturday, April 30, 2022

The speedometer wouldn’t lie, would it? Part 2

 With the engine installed, it was rolled back into the shop and onto the bike lift for the next phase. The rear tire was a 3.50x18” that was rubbing up against the forward edge of the rear fender, due to it being oversized and the fender had an odd dent in the edge that closed the gap even further. I had to park the bike on a 3/4” steel plate to get some wheel clearance on the rear wheel, so I could remove it and change the tire back to the normal 3.00x18” size. I had a spare spoke kit handy, so decided to dive in and clean up the rear wheel rim and hub enough to warrant a fresh set of spokes.

The task was complicated by the rear brake backing plate which had nearly new VESRAH rear brake shoes, but the brake cams and pivots for the shoes were mostly glued in place due to ancient grease used in the installation some 30 years ago. You see a lot of mistakes from people who try to do work on these bikes and don’t get it quite right. Small things like over-lubing the brake pivots and cams, and then the brake arm pinch bolt was installed backward for some reason. The over-sized tire was the other mistake which probably was a surprise when the owner tried to put it on the centerstand and found that the bike was sitting on all fours.. both tires and both legs of the stand. The bike becomes pretty unstable on anything except dead flat ground.

The swing arm had to be removed and taken to my friend Rob North for a 5 -minute welding job to reattach the front chain guard tab which are commonly broken off in higher miles bikes. The swing arm pivot bushings were rusted and pitted so were replaced along with new rubber seals on the inside of the swing arm pivots. Every part removed had to be cleaned either in solvent and/or on my grinding wheel’s wire brush side. A fresh DID drive chain was installed onto a somewhat odd set of sprockets. The front 15t sprocket was worn quite a bit, but I had a spare 16t front in my spares boxes. The rear sprocket wasn’t a stock 30, but it was an aftermarket 34t unit. Stock ratios would be 2:1 (15/30), so the 16/34 combo yielded 2.125, just a bit lower that normal. Larger diameter sprockets are easier on drive chains anyway, but I have never built up a bike with this combo before.

Considering that there was mud and gunk all the way up to the ignition coils, it appears that the bike was in some kind of flood or high water event. Much of the bike was covered in thick silt-like mud that needed to be scraped off with a screwdriver or gasket scraper. There are parts of the lower case that are still embedded with the muddy colors.

With the engine bolted up, I had the option of installing a low-cost Pro-Trigger reg/rectifier in place of the stock rectifier. The ignition system also came from Pro-Trigger, which eliminates the points, and condenser ignition system parts. Once dialed in the system kicks out strong sparks from the coils. The battery of choice for these old bikes is the Motobatt AGM battery which has clever post adapters to work on many types of electrical hookups. They provide strong amperage and steady voltage to the electrical system, for complete reliability.

All of the cables were replaced, mostly from Tim McDowell’s Classichondarestoration.com site. Tim supplied new air filters, tubes, rubber bumpers for the side covers, and other small parts that you need when you are refitting a vintage Honda.

The gas tank didn’t look too bad initially, but when I filled it up with Metal Rescue, little pinholes made themselves known all along the bottom seam of the gas tank. I temporarily patched the little leaks with dabs of GOOP and once the tank rust was mostly gone, I rinsed it out and used up the last half of my Caswell tank sealer kit. Once this stuff sets up, it is very hard and fills in small holes and adheres to any remaining clean rust areas, sealing them permanently. Good stuff!

The carburetors were not as bad as I expected, but did spend some time in the ultrasonic cleaner and got fresh gaskets and O-rings for the flanges and insulators. The chromed brass slides were worn along the top edges, but I only had a decent used one for the right side.

I had taken the rear fender off to straighten out the big dent at the bottom front edge, and poked out a few more dents in the mid-section. It’s a daily driver kind of bike with lots of patina, so I didn’t go overboard with dent removal and make it look new. I shot some Honda Cloud Silver on it before reinstalling it, taking care to clean contact areas where grounds were needed for the tail light bracket and to the frame mounts.

The front end showed signs of leaking fork seals, so they were the next to get a look and freshening up. Type 2 forks are easier to replace seals on than the Type 1 forks with chrome seal holders that are often damaged and difficult to remove and replace the seals inside. The difference on Type 2 alloy forks is that the springs are on the outside of the fork tubes, so you have to use a long bolt to thread down into the top of the fork tubes and draw the forks up into the top fork crown.

The fork seal on one side came out, after snap ring removal, with the usual slide-hammer action of drawing the fork tube up and down against the bottom of the seal until it pops out. The seal on the opposite side was having none of this kind of action. Repeated hammering on the fork case with a plastic hammer and even using the axle for a point of contact failed to release the fork seal. I tried a heat gun but had no luck either. Finally, I broke out the Mapp-Gas torch and gave it a minute of direct flame heat. It finally let go, splattering fork oil all over the floor when the fork case dropped off the end of the tube.

I cleaned the parts, reinstalled the seals, loaded them up with synthetic ATF oil from the auto parts store, and guided them back up inside the fork covers and steering stem. The last big task was the front wheel and brake panel.

Like most of the other parts on the chassis, the front brake drum was rusted in numerous places and the brake shoes were glazed and coated with dirt. De-rusting the brake drum requires a first scraping of the high rust spots with the edge of a flat-bladed screwdriver, then follows with a small stainless wire wheel chucked up in a cordless drill. A final pass with some sandpaper and brake cleaner usually results in a surface that the brake shoes can grip once again.

The brake backing plates are difficult to disassemble as the brake shoe pivot bolts are screwed into the panel then thin nuts tightened up on the outer surface, with little staked points to prevent them from loosening up on their own. A combination of 17 and 19mm sockets broke the nuts loose, allowing for the pivot bolts to be unscrewed from the brake plate. The staked edges of the bolts can damage the threaded holes on the way out if you don’t trim the edges of the bolt threads. It is a good idea to run a tap back through the holes before reinserting the bolts again. All the brake cams were gummed up and the holes in the backing plates were similarly contaminated with ancient grease installed at the factory some 60 years ago.

With the front wheel all bolted back up, it was time to fuel up the newly sealed fuel tank, install the seat, and take it for a ride. The bike started up quickly and the clutch was buttery smooth when 1st gear was selected. A first ride around the block went well, but the front end of the bike seemed to hop up and down as it gained speed. I checked the forks to see if they were working smoothly and then discovered that the ancient front CS brand tire seemed to have not been seated on the rim all the way around. I deflated it, sprayed some silicone spray around the bead and reinflated it, but the tire had some distortion beyond the bead area, so it needed to be replaced. According to the date code of 500, I assume that the tire was produced in May of 2000, some 22 years ago. Too bad because it looked like it had little wear and wasn’t cracked on the sidewalls, but there was no fixing the big hop on the tire as the wheel turned round and round.

Cosmetically, the right side muffler, which looked correct at first, turned out to be a lightweight Dixie International copy, made many years ago. There were several surface rust areas, probably due to battery acid stains on the outside. The left side muffler was an OEM original, but it had suffered some big blows to the bottom sides from some kind of impact; perhaps a rock. I searched for a cheap replacement and found that DavidSilverSpares.com had some “dented” left side mufflers for sale at a reduced price. 

These were units that were being made in the UK as replacements for the non-existent originals, but for some reason the tooling for the left sides was not correctly formed and the bump on the forward section, just behind the forward bolt mounting hole, comes in contact with the back of the clutch cover. I had seen this problem previously on the mufflers that are on my Black CB77 bike and we had to have the weld line ground down and re-welded flat to make clearance for the muffler’s contact point.

Rob North was again my go-to for welding, but he had difficulties in filling in the hole as the material was ground very thin and it was difficult to get welding rod to stick to the metal without melting it away. He spent about 15 minutes slowly closing up the hole until he succeeded in sealing it up.

So, just after a month of the purchase of a very sad, very dirty and very seized up CB77, it lives again and is ready for service once the title work gets done. For the moment, I have three CB77s in service; in Black, Blue and White.

Next step was to haul the bike and paperwork over to the DMV office for verification and getting a fresh title created. The bike was in “no record” status due to the last tags shown as 1989, so you have to start from scratch and do the steps to get it legal again with a fresh CA title. I was able to get the DMV steps started but getting a CHP inspection is currently backed up for more than a month, so the bike is in limbo now. 

Contact me at www.vintagehonda.com for details or to talk about a purchase of this or one of my other CB77s for sale. 

4/22

Bill "MrHonda" Silver





Thursday, April 21, 2022

The speedometer wouldn’t lie, would it? Part 1

Well, another ailing CB77 has found its way to my door/shop; this time a fairly rare blue 1966 edition. The lead came from the vintagehondatwins.com site, when I was assisting a different person about a 305 question. This one popped up showing a speedometer reading of 2340 miles. The brief description was that it was stored in someone’s collection for over 15 years (CA license plate shows 1992 tag) and came without a title or other paperwork.

I was able to have a conversation with the current owner who had picked it up recently from a chance encounter with a man at a cars and coffee Saturday morning event. The bike has a seized engine, but initially the seller was describing a ribbed front tire that appeared to be in excellent condition, perhaps indicating that it was an original item. While the conversation continued more details came up that cast a shadow on the “originality” of the bike and the tires. The tires were from Cheng Shen, out of Taiwan, a common replacement back in the 1980-90s. The front tire size was not correct at 3.00x18 (date code 500). The rear was a 3.50x18 which causes the bike to be unsteady on the centerstand due to the increased overall circumference of the tires.


The chain guard's forward tab on the swingarm
was broken free and the chain guard was chromed at sometime in its life. The bike is a 24xxx model, so was originally equipped with the low, flat-bar handlebar setup. The bike had 1975 Oklahoma inspection stickers on the front fork, but the CA license plate was the blue version dating back into the 1970-80s era. The fork cover has some dents and there is a dent on the top of the fuel tank, plus lots of scratches all over and the usual rust buildup in the nooks and crannies of the frame. The mufflers are OEM, but the right side has some rust patches on the outside and some battery acid damage and the left side has major dents from some kind of impact.

After some negotiations, we came to an agreement, which included meeting me about half-way down from its location in Santa Clarita, which is where the last CB77 came from. It is a 340 mile round trip from San Diego, so a meetup in Anaheim was a big help even at additional cost to offset his costs and time to drag it halfway down the road.

Initial impressions were that the bike had had it’s share of use, beyond 2300 miles, given the changed tires, broken chain guard tab and after a closer inspection one of the cylinder head nuts had been replaced with a plain hex nut, so it was looking less and less like the speedometer was the original unit that came with the bike from the factory. Still, I am a sucker for a Super Hawk, so we concluded the deal and I brought it back the last 100 miles to home again.

First order of business is to remove the engine and get it on the bench for a top end teardown and inspection to see just what has happened to it in the past 20-30 years. In the meantime, I ordered another AGM Motobatt battery and a rear tire for the bike, which will be followed by a complete set of new cables, fuel tank cleanout, petcock overhaul, carb overhaul, gasket kit and seal kit and whatever else it will need to get operational again.

Day 2

The engine was lowered down on my portable bike lift and then given a wash down to get the worst of the dirt and grease off of the outside of the engine casings. After a little scrub-up, the engine was hoisted up on the workbench. I always loosen the outside case screws on the cylinder head and clutch cover before I go to far into a teardown. Using the mass of the engine to hold things steady, my impact driver got a good workout loosening the screws, especially in the head where they appeared to be unmolested since the bike was assembled in 1966, which was noted on the factory wiring harness tag.

Based upon the wear on the sprockets and other chassis parts, it is doubtful that the bike only has the original miles that are showing on the speedometer. All the cables are beyond shot, the drive chain is worn out. The broken chain guard tab doesn’t usually happen at that low of mileage. As parts were removed, the crankshaft was checked for any signs of turning and to my surprise it did turn about one-quarter of a turn and then stopped dead. It would turn backwards for the quarter of a turn, but no more in either direction.

As luck would have it (for a change), the master link was almost right at the top of the cylinder head, giving me easy access to the clip. I string a piece of 22 gauge wire through the ends of the camchain to keep them from falling all the way down the engine cases. The top cover came away and revealed a nicely clean set of cams and rockers. Flipping the head over showed some normal carbon and a bit of corrosion on the valve heads, but nothing was bent, burned or broken. With the head removed, I tried the crankshaft again, but nothing had changed. The pistons looked okay on the crowns, but they would only move up and down a bit then tighten up solidly.

At first I thought that perhaps something was tying up the crankshaft sprocket and primary chain, but a look under the clutch cover didn’t reveal anything out of the ordinary except that the outer surface of the oil filter was showing signs of some kind of unusual rubbing marks. I setup my steering wheel puller which is generally used to push down a stuck piston with success in many cases. Despite the lack of obvious rust or seizure damage the right side piston refused to push down easily, fighting me every mm of the way. After an hour of wrestling with it, I was able to almost see the edge of the wrist pin bore at the bottom of the cylinder block sleeve, but it wasn’t giving up without a big fight. I left it for the night and plotted a new course of action for the next day.

Day 3

Well, it took another hour of pounding and twisting the steering wheel puller in order to extract the stuck piston from the cylinders. I actually wound up getting the cylinders blocked up with a 2x4” piece of wood, then working the piston down far enough to get to the wrist pin/clip. I reached into the center of the crankcase and removed the two bolts holding the camchain guide roller/bracket which left me a clear shot at pushing the pin out using a very long screwdriver. As the cylinders were pulled up, the left side piston released lots of broken bits of piston rings.

The right side piston was still stuck in the bottom of the cylinder sleeve, but it finally popped out with a few more whacks with a hammer and a big drift punch. That piston had all of the rings solidly glued into the piston ring lands. The cylinder walls were actually fairly clean, as far as rust/corrosion goes, but there were some deep grooves in one side and some other irregularities on both sides, especially at the top of the bores.




I finished tearing the rest of the engine apart, noting a burned shift fork and second gear slot. The gear dog engagement was about 10% and the gear dogs were rounded off from repeated jumping in and out of gear.

The clutch pack was a solid mass of plates and friction discs. I pried them apart but the steel plates are all very corroded from sitting pinched together for 30+ years. The clutch pushrod end was holding the steel ball in its grip as the end was an open piece of tubing instead of the normal hardened steel tip. Later comparison with a stock part, revealed that it may have been from a 160 instead of a 250-305 with the extension added to take up the shortfall.

Day 4

The engine cases were covered with a clay, dirt, grease mix that would only release when scrapped off with a screwdriver or other scraping tool. I spent more than 2 hours cleaning, rinsing, cleaning, rinsing and finally getting them reasonably dirt-free. With clean cases, the reassembly can proceed.

The crankshaft locating pins were all installed and the crankshaft assembly reinstalled with all the bearing races engaged with the pins. The main shaft got a good used 2nd gear, offset gear cotters and a new seal. The countershaft was treated to a new low gear bushing, new kickstarter pawl, spring, cap to freshen things up. Obviously, this bike and engine had been driven way more than the indicated miles on the speedometer.

The oil filter was a shocker when I removed the through shaft, instead of old oil drooling out there was a pile of dry dusty, dirty particles that had filled up the filter. I have never seen anything like it, as if there was water filtering through it for awhile. There was no other signs of water contamination inside the engine, but this filter was totally unexpected to find this kind of debris trapped inside.

Day 5

With the lower end buttoned up with a scarce NOS primary chain, I experimented with trying out a set of Barnett clutch plates that were in a pile of spares I went to work on the cylinder head. All the cam lobes and rocker arms seemed to be in great condition. The valves showed typical rounding on the intakes and intake seats, while the exhaust valves looked fine, but the seats seemed to be a bit uneven. Having some issues lately with oil leaks around the head gaskets, I have taken to using some GasketCinch to coat the gaskets and mating surfaces to prevent any more unnecessary engine pulls for unexpected oil leaks.

Day 6

With help from my neighbor, Thomas, the engine was lifted off of the bench and onto my little bike lift, used to raise up bikes without a centerstand. I have found it useful to push CB/CA engines back into their frames, plus it makes it easier to roll the engine around from the shop to the driveway where engines wind up being installed.

With a little jiggling back and forth, the engine was reunited with the chassis and the reassembly continued. I had purchased a set of “CB77” chrome header pipes from an eBay seller in Thailand, but when they arrived I had a bad feeling that they were not made properly. A test fit confirmed that the pipes may have been made for a Dream, as they were 3” longer than the CB header pipes and the bend was so tight that the outlet end was hitting the bottom of the engine cases. The seller refunded the purchase price and said to just keep the pipes.  

Thursday, January 20, 2022

The prodigal son returns home…. Honda CB250RS after 32 years and 38k miles

As soon as I clicked on the Craigslist posting for “collectible Hondas” my eyes popped wide open. The Honda CB250RS 250cc street bike, which I had imported from the UK in 1980, was staring back at me, now for sale about 8 miles from my home. I owned the bike for a couple of years, and then traded it off at the local Honda dealer for the all-new 1983 VF750F Interceptor Sports machine. I think I recall listing the bike on the Cycle Trader magazine, but by the time that a young woman contacted me about it, the deal was done. Not to be deterred, she marched up to the Honda dealer and made a deal on it with them. I’m sure they were relieved to be able to sell it so quickly, as it is really a one-of-a-kind bike in the US.

I was in England for vacation when I discovered the new CB250RS models being released over there. I contacted a dealer who offered it at a good price and instructed him to ship it to me in California, which he did gladly. In order to get it past Customs/EPA I had to sign a waiver that the bike was going to be used for racing purposes only and never be registered for the street. At the time I was in good graces with the local Honda dealer, so I gave them the paperwork and pretty soon I had a clean CA title for the bike and a license plate. I applied for a personalized plate CB250R and was granted that shortly thereafter.

The bike’s biggest adventure with me riding it was a trip to Laguna Seca for the GP races, with a side-trip to Craig Vetter’s place in central CA, where he was organizing one of his famous motorcycle economy runs. Several of the major manufactures were building streamliner bikes out of their Skunk works departments (not factory sanctioned), including Honda that year. There was a $100 prize for each class of participants and I entered with the CB250RS in the 250cc class. Before leaving for the event, I had given the bike a full tune-up, leaned out the main jet one size, geared the front sprocket up a tooth and added Mobil 1 synthetic oil to the engine. With 35 psi in the tires, I was ready to hit the highway.

I found Vetter’s place and wound up sleeping in a side-room Friday night, in preparation for the Saturday morning run up Hwy 1 to Carmel. We fueled up at a local station and had our fuel caps sealed, and then off we went. I had my sleeping bag and other travel gear strapped to the back of the seat and decided to just lay down on the fuel tank and keep the speed at 55mph for the whole run. Other than a big windy corner at Big Sur, which actually blew down one or two of the streamliner entrants, the ride was uneventful. I stopped at the final destination and topped up the tank. The calculation came out to about 91mpg! Surely, I must have won that class with those numbers, I thought. Apparently, not, however as a ratty old Kawasaki 250 street single claimed the first prize at 106mpg!

I slept out under the stars on Saturday night and watched all the racing on the Sunday schedule. About 4PM, I decided that I had better head home as I was due to work on Monday morning at 9AM. I lit out for the Highway and cranked up the throttle to about 75 mph and just held it there until I reached home about midnight. I only refueled twice on the return trip and the bike ran flawlessly. Top speed on the bike is about 90mph, where it gets a little skittish due to light weight (275lbs dry) and a short 52” wheelbase.

I was contacted a couple of times by the new owner, who wanted to know how to contact the Honda dealer in the UK to buy some spares as well as a luggage rack for the bike. The last time we had spoken, the bike had gone on a trip out to Utah and beyond with the miles racking up into the 20k range.

The CL posting included three bikes from the woman’s collection, including a 1966 CB160 and a 1967-ish CD90 in nice Scarlet red with about 3k miles showing on the speedometer. One of the series of photos showed the speedometer/tachometer gauges of the CB250RS… at 42,000+ miles! I contacted the seller, who turned out to be the brother-in-law of the owner who had put all the bikes in storage about 10 years previously. The posting information stated that none of the bikes ran and all had been in deep storage for a decade. After a couple of emails and phone call, I choked down my morning oatmeal and hit the freeway for the quick 15 minute drive to see the bikes. I was warned that someone was headed in from Orange County, so I hope to be there first to have a look at all the bikes. As it turns out, I was the first one there and checked them all over briefly. The CB160 was a complete bike with some pitting on the chrome and some 11k miles showing on the speedometer. The little CD90 was cute, but rather boxy and utilitarian rather than a fun little speedster like its S90 cousins.

I focused on the CB250RS when the out of town visitor made his assessment and an offer on the other two machines. Once they made their deal, the seller turned back to me to confirm our previous negotiated price and I left to go get cash and a pickup truck. After more than 30 years, my little baby CB250RS was coming back home again and I was a happy guy!

Check back for status updates on the bike, as it is resuscitated and rejuvenated back into a running machine after a 10 year sleep.

Bill “MrHonda” Silver



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CB250RS Repairs and Resuscitation Progress

I had the seller’s help in loading the bike into the 1995 Ford F150, but I was worried about the unloading part of the adventure because the bike had NO FRONT BRAKES due to hydraulic failure of the master cylinder. Fortunately, a visiting ATT technician “volunteered” to help me guide it back off the truck without harm to the bike or myself. Once it was on the centerstand, the focus was to get the brakes fixed first. The hefty master cylinder unbolted with a couple of clamp bolts and loosening the banjo fitting on the back of the unit. It had been drooling brake fluid out past the piston seals and dust boot for quite awhile, so all of the brake fluid deposits were mostly hardened and gooey in spots. Some brake cleaner spray in strategic locations, plus my HONDA snap ring pliers combined to remove the piston snap ring to empty out the master cylinder of all the old gummy parts. There was a spare 377 code master cylinder kit in the spares box and it appeared that much of it would fit in this model specific master cylinder. The piston was reused, but the new pressure cups were a perfect match and installed once the bore and body were cleaned thoroughly.

Once the master cylinder was primed again, the unit was reinstalled on the handlebars so that the newly resealed part could do the next task, which was to push the front brake caliper piston out of the caliper bore. Fortunately, this went pretty well, but the caliper seal ring and the piston had some superficial damage due to moisture corrosion from sitting for such a long time. Eventually, the piston was extracted and cleaned. The seal ring was carefully cleaned and inspected for any serious damage. Once the caliper bore and seal ring grooves were cleaned, the old parts were reinstalled. The caliper was remounted on the front fork mount and it bled air out quickly. So, after about an hour’s worth of work, the brake finally had a solid front brake system again.

From there, the seat/tail piece was removed, then the fuel tank taken off and placed aside while the carburetor was loosened up for removal. Once the cables and clamps were all dealt with, the carburetor body came free and was disassembled for inspection and cleaning. The inside of the float bowl was remarkably clean, with just a bit of varnish down in the deepest recesses of the bowl. The pressed-in pilot jet was dislodged, cleaned and reinstalled. The 32mm carburetor has an accelerator pump system installed, with a very long pump diaphragm rod used to contact the carburetor linkage. There were some signs of rust/corrosion from old trapped gas/moisture atop the diaphragm retainer, but it seemed to clean up and should be fully useable once again.

The foam air filter sleeve disintegrated as soon as I touched it, so the whole filter assembly was directed to the trash can, where the remaining filter foam was peeled off and discarded. The filter part number has a -471-code (CB250RS), however checking the part number revealed that the CM250 street bike uses the same part, here in the US. A LOT of the parts on this bike are model specific and a search of eBay auctions all led to UK or Australian sites for any loose parts offered for sale.

The last set of tires installed were a size or two too large, so some smaller rubber is in order to make the bike handle like it did originally. Standard tire sizes are equivalent to 3.00x18 front and 3.50x18 rear, which mount on factory alloy rims.

Although the bike is loosely based upon the XL250 Enduro model, the engine has a larger carburetor, more aggressive camshaft timing and a 9.2:1 compression piston installed. The 5-speed transmission gearing is also more street-biased. The fairing is a Hondaline accessory part, as is the rear luggage rack. Both mufflers have some little skid marks on the outer rear edges, but whatever crashes may have occurred in its life must have been fairly minor.

Numerous receipts came with the bike, showing lots of oil changes, tire changes, chain and sprocket replacements and other minor work. A concern for me was to take a look at the balancer chain tensioner adjustment, which must be done manually. The balancer adjuster is beneath the clutch cover, so that requires draining the oil and removal of the cover and de-compression cables. The adjustment for the balancers is a slotted plate, which is spring loaded. Releasing the locking nut allows the spring to pull the plate across the slotted section until it comes to a stop. After the first couple of adjustments, the balancer chains continue to stretch to the point where the adjustment slot runs out of room. The balancer weight and snap rings must be removed and the adjuster plate relocated on large shaft spines one notch. This puts the adjuster back into a range where future adjustments will continue to be allowed with just a loosening of the locking nut. Fortunately, because the engine is based upon the XL250 design, the engine side cover gaskets and cover seals are still available from Honda dealers.

When I owned the bike, I think other oncoming riders thought it was a Kawasaki 550GPZ, at first glance, due to the dual exhaust pipes feeding into dual mufflers, plus the overall sleek 80’s styling was consistent with other manufacturer’s offerings at the time. The squared off headlights were used extensively in the 1980s by most manufacturers. The headlight bulb is replaceable in this model, but the bulbs may be difficult to source these days. A search for the headlight bulb turned up two new ones in Australia which were $30 each, but shipping was $40! The replacement battery is a YB9-B model, which is fairly common in the US. The petcock is the same as the CM400C models, but cost about $75 each. The petcock lever plate is riveted onto the body, so the inside 4 hole gaskets cannot be replaced without some fancy drilling, tapping and installing new, tiny 3mm metric screws.

With some fresh parts in hand, work continued on completion of the carburetor cleaning and reinstallation. There was about a gallon of fuel in the tank, which was drained out to check the petcock screen condition. Amazingly, the fuel was clear and the tank was clean inside after all those years of storage. Although a new petcock was ordered, the old one was reinstalled as was the old gasoline! The rear wheel was off the bike receiving a replacement 3.50x18 Dunlop K-70 rear tire, taken from a recent CB77 acquisition (way too big for a Super Hawk anyway). The wheel was taken to the local Honda dealer, Southbay Motorsports, which has a tire machine that can remove the old, hardened tire and install a new one without scratching up the 1.85x18 DID alloy rim.

So, with a new battery installed and just one wheel on the bike, the fuel tank was mounted up with a new piece of fuel line and the reconditioned 32mm carburetor fed some 10 year old gasoline for the first time in 10 years! The carburetors have an accelerator pump, which gives a nice squirt of fuel to the intake system. With full choke and a couple of firm kicks, the motor fired right up, sounding none the worse for wear after 42k miles and 10 years of storage! Initially it ran for about 45 seconds, then quit suddenly, which can be a scary event in the event of some kind of catastrophic engine failure, but it turned out that the petcock was in the ON position and there wasn’t enough fuel to feed it until RESERVE was selected. Warming the engine up for 3-4 minutes, the only signs of some aging was a little blue smoke out the mufflers, when the throttle was twisted vigorously. The smoke continued to diminish as the warm-up continued. The old spark plug was a D9EA, which is one range cold for normal use, but fine for continued highway touring. Eventually, the plug fouled over and was replaced with a DR8EA. The old plug came out dry, without signs of excessive oil consumption. So far, so good!

With the rear wheel retrieved and reinstalled, the bike was nearly ready for its first test drive in at least 13 years (last registration tags on the license plate are 2001). It only lasted about 100 feet… I had forgotten to put the petcock back onto RESERVE again! Once it re-fired again, the first stop was the local gas station for a few gallons of fresh premium fuel to mix down the very old gasoline remaining in the fuel tank. With 2.5 gallons of gas, the bike was headed out on its first maiden voyage with the original owner back onboard again. The engine pulls well from moderate engine speeds and the transmission gears are evenly spaced, but shifting is a little bit notchy. With healthy front brakes, strong rear brakes and an engine that purrs, the reunion was a success, rekindling fond memories of my long-lost imported CB250RS Honda and the ride up the California coast over 30 years ago.

A new front tire and tube are on order and will be scheduled for replacement at the earliest possible moment. The new air filter sleeve is installed and a NOS tachometer is coming in from the UK, a recent find on eBay auctions. A trip to DMV will be in the offing, along with signed release of the CB250R license plate, so all the registration, personalized plate and title paperwork will finally be current and in my name. Recently, I had been eyeing a used CBR250R bike as a small, light runaround bike, but most are in the $2500-3500 bracket. With fuel injection and all the modern conveniences, the new 250s achieve some 70+mpg mileage figures, which can certainly save some $$ these days. It will be interesting to see if my 90 mpg figures at the economy run will fall very far down with modern gas, with this machine still being fueled by a conventional 32mm carburetor. If it proves to be reliable and fun, with good mileage, the CB250RS may stay in the stable for awhile, this summer. It’s nice to have my old friend back again.

Bill “MrHonda” Silver













Favor for a friend…

Last November, I received an email message from the wife of a former co-worker when we worked together at a Honda motorcycle dealership back in the 1980s. It started out like this:


Hi Bill,
I am hoping you are the Bill that knew XXXXXX If you remember him, please email me back. I have some info to share. I also have a M/C to ask you about.
Thank you,

XXXXX


Well, I’m probably not the only one who has received similar messages from the spouses of friends, family and co-workers who have passed away in recent years. In a following conversation, I discussed my relationship with her husband in the past and that we had lost touch for some 40 years, but I always thought very highly of him. Her dilemma was that he had left two bikes behind; a 1975 CB750F Super Sport and a 1986 Honda CB700SC. The CB750 was a full tear-down and restoration with a few modified touches done back in the 1980s. The CB700SC was a “Covid project” bike that had been sitting for awhile. It’s still a mystery as how she knew my name and how to reach me, but we called it divine intervention and left it at that.


Supposedly the bikes had been run regularly and ridden enough to keep everything functional, but when I got to them in early Jan 2022, they were not ready to ride or sell. The CB750 was in her garage and when I started it up, the bike coughed and barely ran with a full choke. Pushing it across the garage floor felt very heavy, denoting a lack of air in the tires. We rounded up an air compressor and pumped the tires up from 10 psi up to the mid-30s, which gave the bike a much lighter feel right away. It still really didn’t run much better after 10 minutes of idling and a brief run around the neighborhood, but I could see that an enormous amount of work and care had gone into the rebuild of the bike, so it was just a matter of a carb clean and tune-up to get it going again.


Rather than haul both bikes out, plus numerous boxes of spare parts, we settled on me just taking the CB750 home first along with its box of extras and see what could be done with it to make it marketable in the near future. It was an hour and a half drive up to the Inland Empire where they had purchased a home in a golf resort and I mused about what I had gotten myself into in this quest to help a friend’s family with finding a good home for the bike.


When we first talked at the end of 2021, their daughters were dead set against their mom making any sudden decisions about disposition of the bikes because they knew how much they meant to their dad. I backed off and told her that I was available whenever they were ready to make some changes in the situation. Two months later, the dust had settled, grief had passed somewhat and they agreed to start letting go of the bikes.


CB750K series bikes (4 muffler versions) have risen in prices greatly in the past few years. For the CB750 F Super Sports, the market hasn’t been so enthusiastic although the basic motorcycles are both based upon the same engine design. The 1975 models were the first generations of the Super Sport line-up with the 4into1 exhaust systems, which included the CB400F and CB550F Super Sports editions. The first generation 750s still had wire spoke wheels, but featured a rear disc brake and a more racy style than the K model bikes. The 1975-76 bikes were pretty much the same, but the model got a major revamp for the last two years (1977-78) of the SOHC 750 Four which came with Comstar wheels, blacked-out motor finish and more aggressive cams, canted valves and higher compression engines.


With some assistance on both the loading and unloading ends of the trip, I was able to get the big 750 down to earth from my Tacoma’s bed, ready for some evaluation of the running problems. I was able to access one of the pilot jets in a carburetor and it was plugged up, so I had to assume that the rest of the carbs would need attention. Fortunately, removal of the air box and carbs is a lot easier than the later DOHC models, so the carbs were out and on the workbench pretty quickly.


Popping the bowls off revealed little in the way of varnish or major contamination, apart from the plugged idle jets. What was more evident was the amount of old dried up varnish deposits on the bottoms of the carb throats both on the inlet and outlet sides of the bodies. A little Dremel sized brass tipped brush in a drill motor swept away the varnish deposits and a quick squirt of brake cleaner washed away the evidence for the most part.


The jets were slightly over-sized to compensate for the Kerker branded 4into1 exhaust system, which is about 20 pounds lighter than the OEM system that had a large cigar-shaped muffler attached at the back. Aftermarket systems generally need a bit of enrichening to help keep the air/fuel ratios in balance after some of the back-pressure was released. I rechecked the float levels and buttoned the carb rack back up for re-installation on the bike. Running a separate remote fuel tank to feed the carbs, I noticed an improvement in starting and running as it warmed up, but there was still some irregularities in the sound of the engine’s exhaust note.


Checking the spark timing with a dynamic timing light, I noticed that the 1-4 cylinders were working well but the 2-3 coils were firing erratically. Misfiring problems like this are caused by a number of factors including dirty point contact faces, weak condensers, loose coil wire connections on the primary side and problems with the spark plug caps or the coils themselves.


Removing all the spark plugs gave me a chance to check the compression readings, look at the spark plugs and check the spark plug caps for resistance values out of the 5k ohm range. When I unscrewed the spark plug caps, the one for the number three cylinder was kind of glued onto the wire. As I pulled and twisted it finally came off, but there was a big buildup of burned rubber and plastic from an arcing plug wire that was not making good contact with the inside of the plug cap. That spark plug was dark and fuel-fouling, but I also noticed that that plug was a D7ES instead of the correct D8ES series. I can only guess that the plug was fouling and replaced by a hotter one to lessen the effect. A fresh set of correct NGK plugs, all plug caps testing in around 5k ohms and tightly connected to the plug wires which were cut back a little to access new wire made all the difference in the way the bike idled and took throttle. The timing light stayed steady under increased rpms, so that was the whole issue with the engine performance… a poorly connected plug cap.


Out for a Sunday ride…


Once I had confidence in the bike, after a couple of local test rides, I decided to give it a full test on Sunday with my Jamuligan friends to run up to the mountains for our breakfast run. The bike ran fine and I even ran it up to around 90 mph indicated with no ill-effects. The only problem for the ride was when I was stopping in my driveway and put the side-stand down. Or I thought I had put it down.. As I started to dismount from the bike I realized that the side-stand hadn’t come all the way forward and was folding back up as the bike tipped over towards the ground. My reactions were to plant my left foot firmly on the ground and lift the bike back upwards to reset the stand again. Something in my left leg went POP and I got all light-headed like I was going into shock! I was able to deploy the stand and set the bike down on it properly, but then had to just stand there for a couple of minutes while my body could recover enough to allow me to move away from the bike and remove my helmet and gloves. I limped back into the house and collapsed in a living room chair. The last time something went POP in my body, I had severely sprained my right ankle and it took me out for a couple of weeks.


Fortunately, the damage wasn’t as bad as the one in the past but I iced it and have been treating it with whatever I had available to reduce swelling and pain. I was able to walk around with some pain present, but as the leg warmed up and the muscles lengthened again, I could manage okay, but carefully. I’m sure my friend would have appreciated the fact that I saved the bike from a rollover and certain damage from hitting the concrete.


So, that was the last big ride experience for me and the CB750F. It was listed on FB marketplace, Craigslist and eBay for sale hopefully to find an appreciative new owner who understands the work that went into rebuilding the bike back from scratch. If I didn’t already own a 2020 Royal Enfield 650, I would have bought it to keep for myself. It’s really a nice example of Honda’s mid-1970s efforts for the CB750 Four.

Moments like this cause us to reflect on our own mortality and wonder who will step in to take care of our parts, bikes and unfinished projects when we depart planet earth. Plan ahead if you can...


Bill Silver

aka MrHonda

01-22




Friday, January 14, 2022

When BIG BANGS are not just a theory…

Some rather grisly engine blow-ups have come my way in the past few months and each one was unique in its own way.

First, a “Restored” CL77 305 Scrambler came down from LA because “I can’t get it started” and he thought that I could get it going for him on a “Drive-by” repair stop. I try my best to get small-ish bike repairs turned back around in a few hours, if at all possible. It’s a 3-5 hour round trip from Temecula, the OC, and much of LA, so it is a real commitment to bring a bike down for me to peer into and hopefully get squared away in one trip.

The CL77 was picked up in WA state off of a Craigslist posting by the current owner who was visiting his daughter up North. The seller was a “car restoration guy” who loved the looks of the 305 Scramblers and wanted to restore one. When it arrived, it was evident that a lot of work had gone into the bike, cosmetically, but the mechanical status was unclear. So, the first test is a compression test to see if we have some kind of foundation to build from. In this case, the left side was 175psi and the right side was reading 60 psi! The next step is to adjust the valves and cam timing to see if the compression readings will come up, due to a leaking/sticking valve, perhaps.

The battery was charged enough to make the bike run, but given the previous attempts by the owner, I guessed that the pilot (idle jets) were probably plugged up. For those in the know, working on the carburetors on a 250-305 Scrambler are a real PIA due to the right side proximity to the exhaust system. Clearing the right side carb idle jet was relatively easy and necessary due to a plugged-up #38 jet hole. Sometimes, you can reach under the right side carburetor with the transmission cover removed and pop the left side float bowl off to access the jets. Getting a short, slender screwdriver up inside the well for the pilot jet is always taxing and often you wind up having to remove the carb in order to get clear access to the jet. And in this case, the carb needed to be removed, which entails loosening the whole exhaust system, then easing the left air cleaner cover off, to allow access to the little short 6mm bolts that hold the filter to the mounting brackets.

With bolts removed, the air filter tube must be loosened from the carb inlet and the whole assembly set aside. Then, with just the right 10mm wrenches, the two mounting nuts can be removed allowing the carb to be pulled off of the studs and turned to give access to the jets. Sure enough, the pilot jet on the left carb was plugged up, too. Removing the carb from the cylinder head opens up more issues concerning flattened out o-rings on the carb flange and insulator, plus often the float bowl gasket expands if exposed to alcohol-based gasoline making reassembly impossible without replacing the old gasket with a new spare or sometimes washing the old gasket in hot, soapy water and then giving a bit of sunlight or a heat gun treatment to drive out the alcohol from the rubber gaskets. With the bowl off it is a good idea to check the float level settings, as I have seen many, many carbs with reversed float level settings. The float level mantra for 250-305s is “26mm carbs get 22.5mm float levels and 22mm carbs get 26.5mm float levels”

Once everything was checked over and reinstalled the bike started up on the second kick I did recheck the ignition timing statically before starting it up and then always recheck it with a dynamic timing light when the engine is running to determine if the spark advancer mechanism is working or worn/broken.

The second kick startup was a nice surprise, however, the breather tube which was pointed out to the right side yielded a constant stream of blue smoke due to oil burning. The owner took one look and said, “Can you fix it, please?” I agreed and by the time the owner had returned to LA I had the engine out of the chassis and on the workbench for a peek into the top end. When the cylinder head came off, there was a noticeable notch in the top outer edge of the right side piston. When the cylinders were removed a large burned-through spot on the piston crown extended all the way down past the piston rings. That must have made a noise when it let loose. The head gasket fire ring was burned through as well, so something caused enough detonation long enough to torch the piston crown and head gasket at the same time. These are rather unusual events. Pistons often seize first before they get burned through the tops and the burn area is often in the middle of the piston crown, rather than down one edge.

In any case, the cylinders got a re-bore and some .50 oversized pistons, plus a set of new valves. When the owner came back he was delighted to find that the bike would start up on a couple of kicks and no longer spouted blue smoke and droplets out the breather tube. One down and more to go…

The second bike was also a CL72, which came down from LA, as well. I had briefly looked at the bike’s condition on a return run from Vegas after the Mecum auction. I transported my purchase and a 1962 CB72 for my friend on the way back home to San Diego. He mentioned that the CL72 had been a daily driver for a couple of years, then one day while cruising along at moderate speeds the bike suddenly went BANG and quit instantly. I did a few quick checks on the engine and discovered a tight exhaust valve. I backed off the adjuster quite away until it had more than enough clearance, then tried to kick-start it. BANG again! No more time to spend on a dead Scrambler, so it was left behind while I finished the trek back to San Diego.

Fast forward a year and a half… the bike and owner came down to resolve the engine problem. He helped me extract the engine from the chassis and put the engine up on the workbench. After removal of the cylinder head, we noticed a mangled right-side piston and a broken sleeve flange. Lots of metal and damage to the cylinder liner and the piston, but not too much else took a hit. The bike chassis went back to LA and the engine remained for repairs.

I searched around for a set of cylinders that could be cleaned up and re-bored, but little was available. The owner finally tore down a spare “rebuilt” engine to extract the cylinder and pistons. The pistons were .50 and the cylinders were fairly well-honed, so I just bolted up the parts to the bottom case, installed the cylinder head and camchain, and reassembled it all again.

We reinstalled the engine into the chassis and refitted all the bits until it looked like a whole bike again. It started up after a few kicks but wasn’t idling well, so it was back to pulling pilot jets again and cleaning them out, checking float levels, and dialing in the ignition timing. The bike went out for a test run and seemed to be running well, but loudly due to straight pipes. The bike went back to LA seemingly running well and was taken out for some local rides successfully. The owner decided to sell the bike and wound up shipping it to a mutual friend on the East Coast. Soon after the bike arrived at its new home, the new owner took it out for a test run and about 15 minutes into the drive.. BANG!

It did it again! Same side of the engine, the same type of damage… broken sleeve flange and broken piston/rings.

Collective thoughts were shared online within some private conversations, but the consensus was that the sleeves were loose in the cylinder casting, reducing the amount of heat transfer from the piston to the sleeve to the cylinder block fins for heat dissipation. With piston clearances in the one to two thousandths range, it doesn’t take much to cause them to seize, but breaking the same right side sleeve and piston on the same engine, in the same manner, is more than just a little mystery. Bang, BANG!

Lastly, my friend of many years owns a 1962 Falcon Ranchero and has driven it almost daily for over 20 years. The truck as suffered all kinds of mechanical maladies and some accident damage here and there but was pretty much reliable for short trips to the store and work. A few weeks ago, she got into the truck, turned on the ignition, started the engine, pushed in the clutch pedal to engage 1st gear of the 3-speed manual transmission, and suddenly it all went BANG! The starter was no longer able to turn the engine over and a quick check revealed that the crankshaft was seized up solid for reasons not readily known.

It was towed to my house as I felt that probably the timing chain had broken and wrapped around the crankshaft upfront. After an hour of removing the cooling system and timing chain cover, the results were unremarkable. The timing chain was loose, but still connected to the sprockets and the engine still refused to budge an inch.

We had the truck towed back to her house and rolled into the 1 car garage, which was filled with plastic storage boxes along the whole rear wall, with a toolbox and other assorted packages and furniture bits pushed to the sides. With about 18” of room on both sides, I managed to get the truck up on a couple of jack stands and remove the oil pan to check the crankshaft for a thrown rod or seized bearing… nothing.

Figuring that the engine would probably have to come out anyway, I removed the driveshaft, then the transmission, and finally the bell housing. When the bell housing was backed off of the engine block there was a “clink” noise and a piece of the pressure plate pivot dropped to the floor. For reasons unknown, the piece broke off of the pressure plate when she had pushed in the clutch pedal and the running engine spun the piece up in between the pressure place and inside of the bell housing, jamming the crankshaft.

The clutch plate was almost down to the rivets anyway, so the whole clutch was replaced along with the throw-out bearing. I was unable to extract the pilot bearing which was a small ball bearing instead of a brass bushing, so it was left as-is. Using a bike lift stand slid under the truck, I was able to reinstall the transmission after a great deal of effort and force. The oil pan was reinstalled with a new gasket, as was the front cover after a new timing chain and gears were put in place.

Once the engine was restarted, it became evident that the six-cylinder engine was only running on five cylinders. The number three cylinder wasn’t firing, but the big mystery to that was the spark plug and wire were fine, but no spark was coming out of the distributor cap just on number three! Changing the cap didn’t fix it and finally, I realized that the distributor shaft was worn out so far as to change the point gap at least. .020”

Somehow, when running the wobbling shaft was skipping number three cylinder! A rebuilt distributor solved the problem and the truck began running on all six cylinders once again. While success was achieved in getting the engine to run again, a leaking pinion shaft seal at the rear axle has drained out a good bit of the gear oil and is causing gear noise at the rear axle. That repair will have to go to a shop as I have become fully depleted by the work entailed in bringing a 50-year-old Ford Falcon Ranchero back to a half-life state.

PS. On the way to the transmission shop, the truck died quietly on the freeway about a mile from home. It was towed to the shop where the mechanic said that the pinion bearing was worn and a new seal wasn’t going to fix the leak problem. AAA came and got the truck, brought it to my house where I diagnosed that the new points in the rebuilt distributor had worn themselves down to nothing in less than 20 miles. I cranked the points back open to .025” again, the truck fired up and drove home without issues. The crappy points were replaced with Blue Streak brand units and the truck continues to run the best that it can.  However, the writing was on the wall about the long-term reliability of this 60-year-old Falcon, so it was replaced by a 2003 Mini-Cooper! So, I bid farewell to the Ranchero (aka Mr. Toad) and its mechanical neediness.

Hopefully, that is the end of the big bang adventures.


Bill Silver

aka MrHonda

1-22





Monday, December 27, 2021

Pointing to the past…

I subscribe to many FB forums, plus have my own stream of customers who contact me through my website: www.vintagehonda.com for help with their 50-60+ year old vintage Hondas. For those who are coming new to the hobby and the mysteries of old-school motorcycles, the subject of “points and condenser” ignition systems comes up often. In the 21st Century, the prevalence of electronic and CDI ignition systems overshadows the 20th Century ignition systems, which appear primitive by design.


The points and condenser ignition system, originated by Charles Kettering, is described on many websites like: https://ratwell.com/mirror/users.mrbean.net.au/~rover/ketterin.htm and

https://www.wikiwand.com/en/Ignition_system


As applied to vintage Honda motorcycles, the function is the same as the automotive systems, which had distributors to feed sparks to multiple cylinders, one at a time. On a simple motorcycle engine, the ignition systems started out with self-powered magnetos, which mostly have a fixed ignition timing and do not require a battery to power the units. 


Early Honda 50-70cc models all have magneto ignitions, most of which are fixed spark advance designs. Small-bore engines can run successfully on a fixed ignition as they are easy to kick over and start and the spark timing doesn’t cause undue engine heat buildup as what would happen on a larger displacement engine. In the case of the first-generation Honda Cub 50cc models, the kickstart models had 35 degrees of spark timing built-in. However, the electric-start C102 models needed a retarded spark timing to allow the starter motor to more easily turn the engine over at cranking speeds. So, only those models have a mechanical spark advance system built into the flywheel.


Magneto ignitions use a set of contact points and a condenser to manage spark production. They are “live” all the time, so in order to shut the engine off, you have to have a “kill switch” of some design to short the primary voltage to ground. When Honda went into the realm of CDI (capacitive ignition systems) in the late 1970s, they were also self-powered and required a kill system to shut down the sparks.


In their basic form, the ignition points are a variable switch that turns the ignition coil on and off. They are variable, in that the point gap can be adjusted by changing the point base in relation to the spring-loaded, movable point arm, which is operated by the rubbing block. The rubbing block rides on the eccentric point cam and follows the profile of the cam lobe.



                                                  Drawing from AHMC training materials

The problems with the point system are that the rubbing block eventually wears down a little at a time, which reduces the point gap. As the gap decreases, the opening point becomes later and later, which delays the spark timing to the engine. On a normal tune-up, the contact faces are cleaned with an abrasive to increase metal-to-metal contact which ensures more voltage going to the coils. Then the point gap is enlarged by the adjustment of the point base screws. This brings the ignition timing back to factory specifications and ensures proper engine performance. To reduce the amount of wear on the rubbing block, high-temperature grease is used to lubricate the point cam. On some point plates, a piece of oil-absorbing felt is located next to the point cam and a drop of engine oil keeps it wet and lubricated.


The point contact faces are generally made from a metal called tungsten, which has high resistance to arcing and metal transfer when the points open. When the points are closed, the current is allowed to flow through the ignition coil building up a high voltage charge. When the points are pushed open by the point cam, the voltage flow is interrupted and the points are subject to an arc/spark which jumps across the faces as the voltage tries to maintain the connection. The use of a condenser in the circuit absorbs the arcing force momentarily, then discharges it back to the ground when the points are closed again.


In battery-powered ignition systems, the power flow is from the battery to the ignition switch, then to the ignition coil. Some models will route the power through a handlebar-mounted kill switch so that the ignition can be switched off quickly in an emergency or to shut the bike down without reaching for the ignition switch. A defective kill switch can cause “no-spark” issues when the contacts become corroded or the connecting wires to and from the switch are loose or grounded by a pinched wire in the handlebar switches.


When all the wiring is intact, the battery voltage routes to the ignition coil which generates several thousand volts when the points are closed. The coil discharges the spark energy when the points are opened, dumping the high voltage out of the spark plug wire to the spark plug where it jumps the plug gap and creates a kernel of energy that ignites the fuel/air mixture inside the cylinder’s combustion chamber.


The timing of the ignition is critical to the engine’s performance as the fuel mixture is compressed prior to combustion. At slow idle speeds, the spark timing should be about five to ten degrees before top dead center on the compression stroke. As engine speed increases, the time available for the combustion charge to ignite also needs to speed up, and the spark timing is advanced by the point advancer unit.


The spark advancer is generally a system of weights and springs where the springs hold the weights in retarded mode and then the weights will overcome spring tension as the centrifugal force increases with engine RPMs. The weights pivot on locating pins and interact with the point cam at the base where the point cam rotates on the advancer base shaft. The point cam then shifts the opening moment earlier in conjunction with the increase in engine revolutions. Full spark timing advance generally occurs about 30-45 degrees before top dead center of the piston above 3,000 RPMs.


The configuration of the engine in regards to compression ratio, cam timing, and shape of the combustion chamber dictates how much spark timing is required to make the best use of the fuel available. When spark timing occurs too early or late, fuel energy is wasted and results in unburned fuels going out of the exhaust system which is a major contributor to air pollution as well as poor engine performance and dismal fuel economy results.


Spark timing directly affects the engine’s manifold vacuum signals to the carburetor metering circuits. As spark timing advances, the engine vacuum signals rise pulling in more and more fuel through the idle and main metering channels. In the case of the archaic spark advance systems in the 1960s Honda 250-305cc twins, the mechanism for advancing the spark timing is inside the camshaft sprocket and not serviceable without engine removal and splitting the two cams apart in order to remove the sprocket assembly.


This system, designed in the late 1950s, seems to be compact and self-lubricating, however, problems occur when the springs lose tension, the weights wear out on the pivot pins, and the little molded rubber stopper cushions on the weights either compress or dislodge from the weight faces. Furthermore, the camsprocket is basically riveted together and the rivets loosen up after many miles causing erratic camshaft timing as well as ignition timing irregularities.


All of these factors create a condition where the spark timing advances prematurely at idle from the normal five degrees before top dead center to twenty or more degrees. With increased spark timing the engine responds by speeding up unnecessarily. The engine speed increase causes more fuel to be drawn through the idle circuits further fueling the tendency to increase engine speed further. This snowball effect overcomes the carburetor’s ability to control idle speeds by the use of the idle speed screws and idle mixture screws.


On the market now are several electronic ignition systems that do away with the points and condenser, but still rely on the mechanical spark advancer for that function. These systems are magnetically triggered and are mostly immune to any wobble at the advancer in the case of the 250-305s.


https://www.vintagehondashop.com/ offers the most affordable solution to replace the twin sets of points and condensers of the CB/CL72-77 Honda twins (1961-67) for $159, as well as a designated system for the single point 250-305 Dreams ($139) plus a regulator-rectifier for $39.


There are other companies offering ignition systems for vintage Hondas including Charlie’s Place https://www.charlies-place.com/ and a company in Germany that makes a crankshaft-mounted system for the 250-305 twins. https://www.elektronik-sachse.de/shopsystem-3/en/digital-ignition-zdg-3-23-for-honda-cb72-77.html Prices range from $250-400+


While OEM points and condenser ignitions were perfectly fine for their uses when the bikes were built in the 1960-70s, the new electronic systems are maintenance-free and provide a clean trigger signal to the ignition coils for a fast and maximum spark burst to the spark plugs. Maybe it is time for you to bring your bike’s ignition system up to 21st Century specifications now.


Bill Silver

aka MrHonda

www.vintagehonda.com