Thursday, March 5, 2020

Rescue and Resuscitation: 1981 CB650 Custom

I have worked on a couple of CB650s, over the past few years, but can’t say that I have ever owned one until this February! I was watching a poor bike languishing in the Craigslist postings for about 10 days feeling sorry for its lack of care. The seller only posted one photo from about 30 feet away, so you really can’t see how good/bad it really is. The meager text in the posting mentions that the bike only had 4,000 original miles on the clocks and needed “carb cleaning” and some general TLC. This bike comes under the definition of “barn find,” which can lead to a “learning experience” or send you to a financial “black hole” of unexpected work and parts purchases.

The CB650s were the last of the generation of mid-sized Honda Fours, which began as the CB500 Four, then got a big bore increase to 550cc. Honda stroked the engine out to about 627cc, which Honda rounded off to 650cc, as a model descriptor. By 1981, the engine was rated at 63 horsepower (up from the original 59 horsepower in 1979), not too much shy of the original CB750s 67 horsepower rating, however in a much lighter chassis, weighing in at around 480 lbs. Honda made numerous changes to the machine through the years of 1979-82. The stock slide-type carburetors were replaced with larger 31mm CV carburetors in 1981. The CB650 Custom had new forks, double-disc brakes up front, Comstar wheels, 4 into 4 mufflers and pull-back handlebars. Quarter mile times were 13.6 seconds at 95 mph.

After a 1-hour drive to North San Diego County, I was able to have a close-up look at the poor, neglected Honda 650 Custom. The last registration tags were from 1988 and supposedly the carburetors had been cleaned at some unspecified point in time. The first thing I noticed that the coil wires had been replaced with some very LONG wires and that the 1-4 coil leads were connected to 1-3 cylinders, while the 2-3 cylinder coils were connected to 2-4 cylinders. The battery had been charged up enough to hear the engine crank over, but it gave no signs of trying to start up on its own.

The front brake master cylinder plunger was stuck all the way IN, so there was no way to pump up any pressure to the front brakes. Removing the gas cap revealed that someone had sloshed some KREEM tank sealer inside and some of it had anchored the internal fuel filter in place. The gas cap latching function was sluggish and appeared to be both corroded and perhaps plugged up with some tank sealer residues.

The tires were the original Dunlop Qualifiers, with expected weather checking and dry rot on the sidewalls. Tire tread did help to verify that the bike only had the 4k miles showing on the odometer. The right side mirror and some scuff marks and the fuel tank had a dent along the top right edge. With more than a little reluctance, I decided to adopt the poor machine and do what I could to bring it back to life without breaking the bank account. The sale price was $700, which gave me some breathing room as far as procuring necessary parts, but was probably a more than generous offer.

As expected, the carburetors were filled with a jelly-like substance and all of the float valve needles were stuck in the seats. All four slides were stuck in the bores and the accelerator pump plunger was stiff and non-pliable. Carbs were disassembled and bathed in an ultrasonic cleaner for several rounds. My friends at provided me with new tires, carb kits, cables, a master cylinder kit, spark plugs and oil filter bolt/filter/oil for an oil change. Ebay sellers came up with specific O-rings for the oil galley plugs and a good used speedometer/tachometer mount plate to replace the one which had a sheared-off mounting stud.

I found some Metal Rescue gel products at the local auto parts stores, which can be applied with a brush. Let it stand for a few hours and then rinse off and you have much better-looking chrome parts!

The drawback on the 1980s CV carburetors is that the idle jets are pressed-in and not replaceable. This makes a thorough cleaning just about impossible. I know that those who do carburetor overhauls professionally have a method of extracting the jets using a tap to catch some threads on the outside edge of the jets, then somehow being able to pull them out from the carburetor body intact. If you break off the tap or the end of the jet, then it’s “game over” for that carburetor.

After rebuilding the master cylinder, I discovered that the fluid lines were clogged with ancient brake fluid residues. So far, I have been able to push a piece of stainless steel safety wire down the banjo fitting for a few inches, which seems to be where the clogs reside. A combination of the wire and some brake cleaner shot down the fitting managed to open the passageway and allow fluid pressure to flush the lines out down to the calipers. The caliper seals were replaced, after the pistons were finally pumped out with the master cylinder pressure. Bleeding the dual brake lines can be challenging, but eventually the air was expelled and a firm brake lever returned to restore normal brake function.

Initially, once the carbs were back on the engine, the #4 carburetor didn’t seem to be flowing fuel at idle. The exhaust pipe was cold after the engine had run for a few minutes at idle. Raising the engine speed up towards 3-4k allowed the cylinder to begin firing again, causing the engine performance to become uneven as the cylinder cut in and out on the first test drive. A follow-up check of the #4 carburetor’s float bowl and carb top allowed me to poke a slender, tapered jet reamer up inside the idle jet orifice to perhaps clear a blockage in the jet hole. I’m not sure if the carburetor slide spring might not have been tangled up in the return spring, but after everything was reassembled, the engine smoothed out and the engine performance began to sound more normal once again.

The engine sounded a bit noisy in the top end, so all the valve clearances were checked and found to be at specifications. The camchain tensioner needed adjusting, which is accomplished by loosening the lower tensioner cap nut while the engine is idling. A few turns out on the nut and the noise disappeared much to my surprise.

The original drive chain was rusty and corroded, so a replacement chain is one of the last items on the replacement list. Speaking of parts involved, as mentioned above, the list came out something like this:
Spark plugs, oil/filter and new oil filter bolt, master cylinder kit, caliper seals, top end gasket kit, carburetor repair kits, plus #125 main jets (replacing the stock #120s). New throttle cables and a new choke cable, plus a new $30 petcock screen set. The knob for the Hi-Low beam switch had been knocked off, so a good used eBay switch assembly was obtained for $20. New tires were mounted and balanced by my friends at National City Motorcycles. So, you can see that even if you get a bike like this for free, the parts required, plus a LOT of labor, makes reviving a “barn-find” bike into a bit of an ordeal, requiring a substantial investment in time and parts.

You never know what someone else has done to a bike in the past and a mysterious lack of turn signal function was traced down to someone putting all the front signal/running light wires into switched hot wire connectors, so the filaments were always on, no matter what the turn signal switch tried to control. A simple rewiring of the front signal wires, put the turn signal function back to normal again.

There is still plenty of de-rusting to do on the chrome parts that have sat collecting dust and rust for most of the past 32 years or so. From its sale in Denver, CO to time in Arkansas, before coming to CA in 1986, the bike has covered more miles in transport than on it’s wheels being driven normally. The factory o-ring drive chain was replaced with a solid-roller DID chain. Despite it’s rather dreary cosmetics, the bike is mechanically pretty sound now. The initial investment cost has doubled since purchase, but it is now fully street-legal in California now and ready for service and new adventures in SoCal.

Bill “MrHonda” Silver

Wednesday, January 8, 2020

Honda CL90-Learner bike

Ironically, my very first motorcycles was a 1967 CL90 Honda Scrambler and that was what was dropped off at the shop just before Christmas for “get running” repairs.
My customer is in his late teens and brought a scruffy CL77 last year for “get running” repairs that got much more complicated than expected. The CL90 project had been powdercoated, chromed up and cleaned up overall, but he never could get it running.

On the bench, I checked the basics and during a timing check could feel roughness in the engine as it was turned over towards TDC. I noticed that none of the four cylinderhead nuts had washers beneath them, including the copper washer used to keep the head from leaking oil. Rookies!

Tearing the top end off of a Honda 90 is about a 5-minute task, so I thought I would take a peek inside. Yikes! The camchain guide pin had been replaced with an 8mm bolt that pinched the roller at the edge, preventing it from rolling at all. The cylinder bore showed old water stains and pitting, plus the piston was showing being seized in about 3 places. Making this one run is going to be expensive and take more than a little time. I noticed that the spark advancer had 918 stamped on the edge, instead of 028. 918 is for an ATC 90 which only has about 25 degrees of spark advance vs. 45 for the CL90 engine. I had to round up a good used one from eBay sellers and that fixed that.

I dropped the engine out of the frame and saw an aftermarket coil and wiring mounted to the top of the engine. The coil wasn’t anchored on both ends because it was a generic part of the wrong dimensions. Plus he had left out the condenser! The wiring connection from the stator to the harness was connected in the wrong location which pulled the whole aftermarket harness downwards. This created a short connection to the headlight shell, which pulled on the wiring when the steering was turned to the left.

There were incorrect fasteners, loose wire connector crimps which came apart when pulled gently. Lots of rookie mistakes all around on the restoration effort. The rear wheel axle nut was just holding the axle in place, but the whole stub shaft for the rear hub was missing!

Quite a bit of time was expended in scraping off old gasket material from the head and cylinder. Whoever had been in there previously had used a cheap gasket kit that used thin green paper material which seems like a single-use material.

There was a lot of carbon build up in the combustion chamber, but the valve seats were not badly damaged from whatever water had gone through the motor in the past. I re-cut new seats and lapped the new valves in place. The cylinder was bored to 1mm over to clean up the bore and eventually it all came back together again.

Somehow the aftermarket ignition had been damaged and was non-functional. My friends at came up with a replacement switch for less than $10, plus gaskets and one of the valves.
The rest of the parts came from eBay sellers. I had guesstimated the whole bill at $500 before I got deeply into the project and with a discounted labor rate it still pushed close to $600. Funny how such a small bike, that sold for about $400 new, costs so much to repair now. Here’s what the total looked like:

$31.71 piston/rings
$12.97 tappet covers
$20.46 spark advancer
$18.94 sealing washers
$10.76 seal kit
$6.53 guide roller pin
$6 8mm guide pin washer
$21.54 cam chain roller
$6.47 8mm washer
$14.00 exhaust valve
$3 Float Bowl Gasket
$15 Intake Valve
$20 Engine Gasket Set
$8 Ignition Switch
$5.95 1qt oil
$5 gasoline
$5 valve stem seal
$40 cylinder boring
$30 Coil and condenser
$5 engine mount bolt/misc hardware
$286.33 parts

Teardown top end for evaluation
Remove engine for rebuild
Order parts (gasket, seals, spark advancer, camchain roller/pin, piston/rings, valves, ignition switch
Remove clutch cover for clutch inspection
Remove original gasket material from head, cylinder, and crankcase
Cut new valve seats/install new valves
Replace ignition components with the correct type
Reinstall wiring harness/repair wire connections/install new ignition switch
Inspect/adjust carburetor components
2 trips to the machine shop for cylinder boring 48 miles
Install new camchain roller/pin
Install new piston/rings
Assemble top end components
Install engine and adjust timing
Inspect and reassemble petcock components
Replace fuel lines
Check compression (150 psi)
Start engine and adjust carburetor
Total labor: 8 hrs. $320 discount rate

The bike fired up quickly and showed plenty of oil circulating in the top end. The compression check showed 150 psi. There’s lots more to do in finishing the rest of the bike, but I did “make it run” in the end.

Bill Silver “aka MrHonda”

Monday, December 9, 2019

My Bonnie lies over the driveway...

In that this story has nothing to do with vintage Hondas, distribution of it will be somewhat limited this time. With apologies to the original song, which I have parodied here for my title:

Speaking of parodies, read down to the first one on the page that echoes my reference to motorcycles! 

My Bonnie leaned over the gas tank,
The height of its contents to see,
I lit a small match to assist her,
O Bring back my Bonnie to me.

     I love my Sunday rides with my Jamuligan friends, switching back and forth between my various small-bore machines of late. I have kind of been missing the torque and heft of my last W650 Kawasaki, but they rarely come up for sale and there isn’t much else that seems to work for me in that category… until this CL posting showed up:

2008 Triumph Bonneville, Black with only 4646 miles.
Does not start and could use some TLC. Registered through SEP 2020.
Looking for $1200 OBO.

Frame: Tubular Steel Cradle
Suspension: Front: 41 Mm Forks Rear: Chromed Spring Twin Shocks With Adjustable Pre-load Rake: 28°Trail: 4.33 In. (110 Mm)
Engine: DOHC, Parallel-twin, 360° Firing Interval Horsepower: 66 Bhp (67 Ps) @ 7,200 Rpm Displacement: 865 Cc Bore x Stroke: 90 X 68 Mm Torque: 52 Ft. Lbs. (71 Nm) @ 6,000 Rpm Compression Ratio: 9.2:1 Fuel System: 2 Carburetors With Throttle Position Sensor And Electric Carburetor Heaters Fuel
Tank Capacity: 4.4 Gal. (16.6 L)
Clutch: Wet, Multi-plate
Cooling: Air/Oil
Transmission: 5-speed Final Drive: X-ring Chain
Body Colors: Claret, Aluminum Silver, Fusion White, Black
Brakes: Front: Single 310 Mm Disc, 2-piston Caliper Rear: Single 255 Mm Disc, 2-piston Caliper
Tires: Front: 100/90 19 Rear: 130/80 17

Manufacturer Description:
A pedigree that few models can match. A true roadster, the Bonneville matches classic British style to 21st century technology. This pairing of authenticity with modernity has led the Bonneville to become an icon in its own right with several famous designers creating their own signature tank designs. A cool way to cover the urban landscape; the Bonneville is agile in jammed streets and at home, blatting down a leafy country lane. It has a pedigree few models can match plus a tangible credibility within today’s motorcycling world. Available is the subtle Bonneville Black – a Jet Black Bonneville complemented by a black engine finish.

I saw this posting on a Saturday night, just before Halloween and thought, “How can I go wrong with a deal like this?” So, I sent an email which was answered quickly. I had leftover cash from the sale of my 1991 Honda Accord, so I was all set to load up the ramp and tie-downs for a quick trip across town to go have a look.

I really don’t advise bike shopping at night, but sometimes time is of the essence, so off I went to investigate this offering. After finding the correct alley address, I was able to see the bike located in a side yard with one floodlight illuminating the poor Triumph. There was no battery in the bike, so I had to assume that the engine still turned over, but given the many experiences I have had with long-term storage of 250-305 Honda engines, that is a questionable assumption.

My current lightweight bikes (1988 CBR250R-45 HP/350lbs and EX500 Kawasaki -50HP/425 lbs) are great fun and easy to handle on my Sunday rides with my Jamuligan friends, but I have been missing that nice fat, torquey feel of my last Kawasaki W650 parallel twin. I have owned three W650s in the past ten years and they were solid, reliable classic-looking machines.

Kawasaki only sold 1500 W650s in the US during 2000-2001 and they are rare to find these days. When the W650s were put on the market, here in the US, the “new Triumph 650” models were hitting the dealerships at the same time. Comparisons were inevitable and the Kawasaki had many strong points, but the Triumphs won out in the end. I’ve never had a chance to ride any of the new Triumph models, but the opportunity arose recently to own one at a bargain price.

The seller was a current military man and had owned the bike since new, however, he had been stationed in Monterey, Virginia, Washington and elsewhere in the past 11 years and the bike had not been ridden since 2011. He had recently moved back to San Diego and made efforts to revive the bike after it had been poorly stored causing rust in the fuel tank and corrosion all over, everywhere else. The bike deal included a couple of leather Triumph-branded leather jackets and the registration tags were good until Sept.. 2020, which is a $129 consideration. I offered $1,000 and he accepted. We loaded the big machine into the Tacoma and off I went, back into the black Saturday night, with my new project.

I really like bikes that have centerstands, which this one did not possess. However, looking underneath the chassis, a pair of mounts for a centerstand were noted. Sure enough, our eBay friends in China were offering a whole centerstand kit for $119 with free shipping for the big Bonneville models.

Surprisingly, the carb rack is pretty much identical to that of the W650 Kawasaki, so I was pretty familiar with the setup. In typical British fashion, there were unexpected challenges as the analysis of the bike’s faults continued. For one thing, the PAIR air system for the emissions control runs big fittings down next to the spark plugs in very close proximity to the plug itself. Most spark plug sockets, which normally have ample room on a Honda ran afoul of the adjacent air fittings.

The TPS switch on the carburetors must be unplugged from a harness connector which is buried just inside the frame tube, making re-connection quite a chore. One of the throttle cable adjusters is right up against the sliding choke connector, as well. The carburetors had not seen fresh fuel through them since 2011, so both were totally gummed up inside. Both float valve needles were completely stuck in the float valve seats due to varnish deposits. One of the idle jets was stuck hard in the carburetor body, requiring lots of carb cleaner, a precision screwdriver tip and a bit of hammering in order dislodge it for cleaning. Several rounds of cleaning in my little ultrasonic cleaner finally dissolved the varnish deposits, allowing all of the parts to be reused during assembly.

The rear chain, spokes, and brake rotor were rusted and corroded, requiring a lot of hand cleaning. The chain was doused in PB Blaster, then some synthetic chain lube. The rear brake rotor cleaned off with steel wool and brake cleaner. The brake pedal is located above the level of the foot-peg, which is an odd angle for your ankle, especially my fused one. The adjustment nut for the brake linkage rod is inaccessible beneath the footpeg bracket.

During pre-purchase inspection, the front fork seals were noted as showing definite signs of leaking. The fork oil then drooled down the left fork leg and onto the brake caliper and rotor.

The fuel tank was drained then filled with a gallon of phosphoric acid and 3 gallons of water, then left to sit for 3 days. Eventually, what appeared to be rust inside the fuel tank was apparently just leftover fuel solids, which dissolved and filled a plastic container full of brownish gunk. Subsequent flushing with water revealed a white coating inside the fuel tank which was apparently unfazed by years of gasoline acids and other byproducts. A good used petcock was purchased from an eBay seller, which had intact fuel screens for the inlet fittings. After a good air dry with compressed air and some time with a heat gun the tank was deemed safe to use, without further treatment.

After carburetor installation, along with a fresh battery, the bike engine spun over eagerly and fired up after a few moments of cranking. The engine sounded a little uneven at idle, which finally was found to be caused by a disconnected vacuum line to the carb manifold fittings.

The Haynes shop manual, which came with the bike, showed a float level setting of what I thought was listed as 13 to 16mm! That seemed to be a rather broad range, given that Honda often specifies float levels in .5mm increments. I used the higher figure to help offset the usual factory leanness in today’s emission controlled carburetors. What appears to be the end result is that the bike, which can only rest on the side stand, allows the carburetors to partially flood the engine if the fuel petcock is left in the ON position. If the petcock is left in ON or RESERVE, the engine becomes very hard to start, often running the battery low until it finally clears its throat and starts up. When the petcock is shut off after each ride, the bike fires up in a few revolutions. I started the bike with the petcock in OFF until it catches and starts running for a minute, then switch the fuel to ON position.

An Internet search seemed to indicate that the float level is really supposed to be 17mm! I contacted a Triumph site that deals in various modifications and hoped to receive some concrete information about what the setting is supposed to be from the factory. I never heard back from them, but verified the setting at the local Triumph dealership.

I realized that I completely mis-read the float level specs in the book. A first casual glance that I thought was 13 to 16mm turned out to be 16 to 18mm, with 17mm given as the popular average to achieve success in proper carburetor calibration. I attempted an on-bike readjustment of the float levels, but apparently the left side didn’t go as planned and the bike suddenly was giving off a backfire through the carburetors, exiting the rubber manifold connectors despite a tight hose clamp at the connection.

That set off a search for new manifolds, which lead to finding one on eBay for $15 delivered. Ultimately, a second one was in stock at the local Triumph motorcycle dealers for about $.25 less money. I bought a new oil filter and a gallon of recommended semi-synthetic oil which ran the bill to past $50, just for the oil and filter.

The Chinese centerstand assembly arrived a few weeks after ordering and failed to impress me with poorly-fitting components and improperly-designed hardware. After spending over an hour in modifying the various parts, the fitted stand would not allow the bike to come up successfully. Messages to the seller proved somewhat fruitless at first, then finally they admitted that the stand really didn’t fit this model machine. While at the Triumph dealer, my friend Issac checked the computers and discovered that there close-out factory stand kits for $120! I laid down my plastic across the counter and put one on order ASAP.

After waiting a few days to receive my centerstand kit, I called the shop only to have them tell me that Triumph had listed the part as centerstand ONLY, not as a kit! All the rest of the hardware bits will probably cost another $100 and some of them might have to come from England, which might take a few weeks! Grrr….. Honda wouldn’t do that to me! Eventually, all the centerstand parts did come in, sooner than expected and the installation went smoothly, so now the bike has a proper centerstand function which makes chain maintenance much easier. After some delays, I was able to receive a full refund for the non-fitting Chinese stand, which they didn’t want to be returned.

I decided to remove the carburetors once more and reset the float levels more precisely and check them for any signs of leftover fuel contamination from the previously contaminated fuel supply. That left side level was off a few millimeters, which was corrected to match the other carburetor. The new manifolds were installed and everything buttoned back up correctly. This time the bike fired up quickly, ran evenly on both sides and didn’t show signs of over-lean or over-rich mixtures. Subsequent test runs bore out the final success of reviving the fuel system from top to bottom.

The fork seals needed attention next, as the fork oil had run down the left side fork and into the brake caliper and brake rotor, leaving a distinct lack of braking feel when the lever was pulled. I carefully read the Hayne’s book and hoisted the bike on my seldom-used bike lift. Extracting the front wheel and fender, the fork tubes slid out of the triple clamps with relative ease. The forks are held together with the inner damper rod, which is retained by an 8mm Allen socket head bolt through the bottom of the fork case. Fortunately, I happened to have a small 3/8ths drive special socket with 8mm bit, which worked perfectly for bolt extraction.

The 41mm forks hold nearly 500cc of oil, once you reassemble them with new seals and dust covers! I used some auto store synthetic transmission fluid for the refill and they seem a little more compliant than before. Once the forks were rebuilt, the brake rotor was cleaned carefully and a new set of pads installed. NOW I have a decent front brake!

Despite its rather tatty appearance, the bike is mechanically very sound and has been taken on a couple of Sunday rides of 60-70 miles each with complete success and enjoyment. I never really expected to be a Triumph owner, but circumstances worked towards reviving this previously neglected machine to fulfill my cosmic request for another big-bore parallel twin for my Sunday entertainment.

Thursday, November 28, 2019

Getting to the Point(s)

Honda used conventional points and condenser ignitions on all of their bikes until about 1978. Nippon Denso was their primary supplier, however, Kokusan and Hitachi components were also used for various ignition and charging system applications. Nippon Denso has ND stamped somewhere on the points base and base plate, as well as on the condensers. Kokusan parts often have a K and Hitachi used either an H or one of their Kanji-based manufacturing marks. Later four-cylinder models used TEK ignition contact sets.

Please note that none of the various branded point sets will interchange with the others. All have unique point plates and methods of adjustments. Many of the replacement points sets available now come from a company called Daiichi who attempted to copy all of the other brands. In some cases, particularly for Honda Dreams, the attempt fails to match the OEM or original manufacturer’s dimensions. I would recommend searching for the original branded point sets or whole point plate assemblies rather than get caught up in the aftermarket branded replacements.

Point cams, which open and close the contact sets are placed in numerous locations, depending upon the engine configuration. Most Honda 50cc Cubs used a magneto ignition, with points and condenser packed beneath the flywheel. The electric-start C102 had a battery ignition system, however. The early pushrod singles all had flywheel-mounted ignitions, as did the 125-150cc Benly twins. Honda's prolific 250-305 twins had a points plate mounted off the right side of the camshaft cover, however, the actual points cam design included a long shaft that tunneled through the hollow camshaft half with an engagement tang, which connected with the central cam sprocket. The160-175-200-350-450 twins all had a removable spark advancer unit, which bolted into the end of the overhead camshaft.

Dual-point sets fired twin-lead coils on the newer-generation 350-400-500-550-750 OHC fours, as well as the early model GL1000 Gold Wings,. All of these engines used the "wasted spark" concept when the spark plugs were connected to two cylinders of 180 degree apart firing sequences. All 250-305 Dreams and almost all 125-200cc twins used a single twin-lead coil, fired by a single set of points.

I have had many questions sent my way concerning bike engines that had either a slow return to idle condition or a continuously fast idle speed, wherein no amount of carburetor adjustment would effect a change to the condition. In the high percentage of cases, the mechanical spark advancers had sticking/frozen advancer cams, nearly welded to the central mounting shaft. Other spark advancer woes include advance weights with oval holes and broken/stretched or missing return springs. Most spark advancers are going to kick in 25 or more degrees of ignition lead when they are activated. When the spark timing advances that far, it changes the vacuum signal to the intake system, drawing more fuel/air than normal through the metering circuits, all of which causes the engine speed to leap upwards despite normal external "adjustments" to the carburetor idle speed screws. As a part of any tune-up procedures, always check the function and condition of the spark advance units, before blaming defective carburetion as the cause.

When misfiring occurs, any component in the carburetion, electrical and ignition system can be the cause. ALWAYS start with cleaning the ignition point contact faces. Lubricate the small felt lubrication pad with a couple of drops of oil and/or lubricate the points cam with special point cam grease. Once the contact faces are clean and parallel to each other, set the gap to approximately .014"-016" when the point rubbing block is up on the highest portion of the point cam ramp. This determines the "dwell" of the ignition coil, also known as saturation period. The ignition coil must have sufficient time to build up an electrical charge in the windings before discharge. If the points are opened too wide, there isn't enough time for them to be closed sufficiently for coil saturation.

When points are closed excessively, there is an increased tendency for them to arc, as well as another phenomena that occur on some dual-point applications. When the point gap is too narrow, there is a moment where both sets of points are momentarily closed, which causes the normally oscillating voltage/current distribution (alternating between the two sets of points) to be tapped by both coils at the same moment. The momentary "double-draw" on the B+ primary feed wire, reduces the available current/voltage to each coil by half. When this happens, both coils are underfed and the maximum voltage output on the secondary windings is greatly reduced. Peak voltage requirements are often when the throttles are cracked open during acceleration. When the momentarily lean air/fuel mixture is inhaled and compressed for firing, a substandard voltage level will cause a BIG misfire/hesitation. ALWAYS ensure that both sets of points are independently open AND closed during the firing cycles. Keeping the point gaps towards the .016" gap measurement will automatically prevent this occurrence.

Numerous other causes for misfiring include a weak/failed condenser and defective spark plug caps (cracked down the sides, causing arcing to ground) or failed internal 5k ohm resistors. Any damaged spark plug wires or spark plug caps not securely fastened to the wire ends add to the list of misfire causes due to ignition deficits. While Honda ignition coils seldom fail in regular service they are not immune from causing misfires when the internal secondary copper wiring either burns open or short across adjacent coil windings. Instead of doing proper trouble-shooting to determine a "no spark" or "weak spark" condition, owners often choose to blame the coil. After paying for this expensive component, they discover that the original coil was not the cause of the fault.

Care must be taken when replacing contact sets, as there is an intricate package of insulators to isolate the movable contact side electrical connections from grounding to the base plate. Placing the "flag terminal" against a grounded post will prevent the coil from firing. Even when the wire terminal is properly sequenced in the terminal connection, a little bit of mispositioning will have the corner of the terminal touching ground against the base plate or sometimes when the point cover is installed.

After 40-50 years of service, the point adjustment and mounting hardware is often damaged from use of ill-fitting screwdrivers. Be aware that pre-1968 hardware threads were JIS threaded, not the later ISO specifications. Any 3, 4 and 5mm screws are specific in their thread pitch.

3mm changed from .6 to .5
4mm changed from .75 to .70
5mm changed from .9 to .8

JIS thread screws are difficult to find, so re-threading the screw holes allows the use of the later ISO screws, which are readily available. For best results, find a new point plate assembly.

In the big scheme of things, points are just adjustable switches, which turn the ignition coils on and off during operation. Clean contacts, adjusted to proper specifications ensures proper ignition timing during all types of operating conditions.

Bill "MrHonda" Silver 11-2019

Monday, November 11, 2019

The Trials of the Trail 90

It should have been pretty straightforward, I thought. I was tasked with reassembling a “project” bike that had been passed along from one friend to another for not much money, a few years ago. The engine was brought to me for a top-end and to un-stick the high-low transfer function of the transmission.

The engine looked like it had been underwater, as the head casting was deeply pockmarked with corrosion and the cylinder bore was rusty. The cylinder was sent out to DRATV for a big bore kit and was reassembled without apparent difficulties. The cylinder head was treated to new valves (aftermarket) but the valve seats seemed to defy being cut in properly. I have both OEM Honda valve set cutters and a partial other seat cutting kit to use, but it seemed that the whole valve guide was offset somehow and the valves leaked every time I reassembled the head.

Fast forward a couple of years and both the engine and chassis returned to me for marrying back together again. There are a lot of little details that seem to take forever to accomplish, but finally it arose from the rusted state towards looking like an actual motorcycle. All the cables were replaced and an aftermarket headlight shell from Thailand was installed with rather poor results as the reproduction part dimensions didn’t fit the headlight rim properly.

Once it was assembled, it failed to start up, despite having most of the ingredients to run. Rechecking the compression revealed only 90 psi, which is marginal for most engines to run at all. The head was removed again and another hour or so devoted to cutting the seats to make a correct seal. After much work, the head was reinstalled and the compression readings came up to 120 psi. It was still difficult to start, but a little bump start down the driveway finally lit it off. Initially, it sounded okay but oil started to leak between the head and cylinder. There is a small rubber sleeve around the only cylinder dowel that feeds oil to the camshaft and rockers, plus a complicated seal that wraps around the camchain tunnel opening.

As a backup, a good used 1969 CT90 head was purchased from eBay seller, but contrary to the seller’s claims, the head was from a CT110, which has completely different head gasket arrangements, plus all of the valve train components were different from the original CT90 types, so that was a dead-end effort.

Researching the engine parts, I noticed that there were two versions of cylinder heads listed for the 1969 CT90, plus apparently some changes to the cylinder, itself, in later editions. I recall seeing the returned cylinder not being the same as the one I shipped out to DRATV, but assumed that they were mostly the same and that we were shipped a cylinder that was already bored and ready to go, instead of getting our original cylinder machined to fit.

When disassembled, nothing appeared to be out of the ordinary or misaligned, but it leaked immediately once again after reassembly. I had parts of another gasket kit with different sealing parts, so I tried those instead, but with the same results. After several rounds of assembly-leak-disassembly went over and over, suddenly the piston was making contact with the edges of the combustion chamber. Marking the combustion chamber numerous times revealed contact up around the intake valve area, just inside the copper head gasket. After a half dozen attempts at carving away material around the combustion chamber, it finally turned over without piston contact.

I contacted DRATV to see if they had problems with piston contact and they said that there were issues, so they include a thicker copper head gasket to move the head away from the piston! They sent one to me at no charge, which was somewhat helpful, but I continued to have the oil leak problems, apparently around the stud knock pin seal. Ron added a bit more complication to the mix when he ordered a set of heavy-duty valve springs and a mild camshaft for the engine, as well. The parts came in with no instructions, as to different valve clearances and if the carb jetting needed changing. I just added an extra thousandth of an inch to the valve clearances.

I ordered an OEM cavity gasket which has an embedded metal base, so it doesn’t squeeze into the camchain tunnel. Finally, I put two sleeve gasket packings on a new knock pin and squeezed it all together. Success, at long last! I verified the ignition timing, which seemed to be suddenly retarded over what it was set to initially and the engine became easier to start and had a much improved idle performance.

There was just one small irritation after another, until I was about to put a torch to it, but resisted the temptation. There’s always a reason for these kinds of problems, but sometimes the answer is not easily discovered, even on such a rudimentary and simple one-cylinder engine like this.

Bill “MrHonda” Silver 11-2019

Sunday, November 10, 2019

Bubble, Bubble… toil and trouble x2

In an effort to find a new home for the Tracy-bodied CB400F, my trip to the El Camino College swap-meet in October yielded a pair of vintage Honda tiddlers, as part of an exchange of vehicles. Outwardly, they looked like fairly intact machines, reportedly both running within the past few months. Well, you know how that story goes…

Exhibit 1. 1967-8 SS125A 125cc twin, showing about 4k miles on the speedometer. Seller claimed to have purchased from an eBay sale and when it arrived and was started up it smoked heavily. One would imagine that the rings were stuck from long-term storage, so a quick top end job might set it right. The right side clutch cover had all the Phillips screws replaced with Allen screws, indicating that perhaps someone had been inside the engine for unknown reasons.

The bike came with a wiring harness in a box, which turned out to be the wiring harness for the bike; not a spare. When the battery cover was removed, the back side of the ignition switch is revealed and it was discovered that all of the connector wires were cut off from the switch. Likewise, the wire ends for the stator connector were cut off, as well. There were two wires leading down to the ignition points connection, instead of just one. The wiring showed signs of newer shrink wrap over the wiring connections, leaving me with a mystery. When mentioned to the previous owner, he said that the bike had been at “Charlie’s Place” in Los Angeles where it was being test fitted for an electronic ignition system. This made more sense, but unfortunately, the project seemed to have been abandoned and I am left with wiring repairs to make. I have a box of misc wiring harnesses and electrical bits, so was able to prune off a couple of matching wire connectors with short leads of wire and patch the cut wires back together again.

I dropped the engine out of the chassis, which is really only held in with 4 bolts. On the bench, the top cover was removed and I was dismayed to see a lack of oil on the cam/rockers and what looked like some heat-related scoring on the cam lobes. The head was removed and mostly just soft carbon was left on the pistons and valves. These engines have little valve stem seals on the exhaust sides, which can harden and then allow some oil to seep into the engine causing smoke.

The cylinders came up next and the pistons were not seized and the rings were all free in the ring lands. Removing the rings and setting them back into the bores to check end gaps revealed little apparent wear on all the parts. I planned to reuse the rings, but noticed a ridge across the top edge of the ring, due to some kind of unusual wear. The 230 code rings are getting scarce and the part number has been superseded to the CB125T model, which uses a 3-piece oil ring set, however that bike was never sold in the US, so parts have to come from somewhere else. I found a salvage business who was parting out a couple of engines, so ordered a used set of pistons/rings, just to get the ring set. Before that, an eBay seller had “CB125” ring sets, which were 44mm but the rings were 1.5mm thick and I needed 1.14mm rings, so those went back to the seller. The set of used CB125T pistons/rings arrived quickly from the eBay seller and thankfully they fit right in. It was interesting that the wrist pins were shorter/lighter than the SS125A versions.

Attention was then focused upon the clutch cover where the oil pump lives. The Allen screws were removed and the cover lifted away. The retainer bolts for the oil pump are secured with a metal strip that has tabs to secure the bolts from backing off. The tabs were in place, but the whole pump was loose on the engine case. Removal of the clutch assembly and oil pump revealed small fragments of a home-made gasket that is supposed to seal the pump to the engine case. Apparently the gasket failed and the oil was squirting out back into the lower end instead of being circulated back up to the cam and rocker arms.

Cleaning the cam and rockers on a soft wire wheel revealed only minor wear marks, so apparently the engine was only run briefly before someone decided that there was a problem with the engine. The cam and rockers were reused, after the valves were de-carboned and new stem seals installed.

A new OEM gasket kit was obtained from an eBay seller, which included the thin paper oil pump gasket, so all the parts were cleaned for reassembly. Not much can go wrong with the oil pumps, as they are a plunger type driven off of the back of the clutch basket and there are two check valves keeping the oil flow going in one direction. I removed the steel balls to clean the pump housing and noticed a thin ring of rust around the middle of the ball where it had been sitting in the same location for years and some moisture in the oil had created a rust ring on the check ball. So, a word to the wise: check your balls before reinstalling the oil pump! These pumps were used on many Honda 125, 150, 160, 350 and 450 twins, so keep this caution in mind if you are having oil pump problems.

The chassis needed new fork seals and boots, new battery, new mirrors, new cables and lever sets. The fuel tank looked to have been coated with a silver coating on the inside, but the outside appeared to have been painted with a brush, perhaps with the same material! The petcock needed replacing, as well. I discovered that the cheap Chinese made petcocks, offered as replacements for the SS125A are not a bolt on fit. The recess for the attaching screw is too small for a common 6mm screw and the sealing washer. The whole standoff for the fuel tubes was too big to fit into the fuel tank opening slot. I eventually was able to get it fitted to the tank, but don’t trust that it will be leak-proof, so bought an NOS Honda petcock for $40 as a backup.

The bike finally fired up after a puzzling event, where the ignition timing was suddenly about 45 degrees off from where I had eye-balled it during the engine build. Oddly, Honda had put two sets of point plate mounting screw holes in the outer cover and when I reset the plate to the previously unused screw holes, the timing lined up successfully.

The engine started up quickly after that, with no smoking at all. A quick check of a tappet cover showed oil flow to the top end in proper quantities. In my excitement to drive the bike, I failed to check the tire pressures and got a flat rear tire about 2 blocks from home! Fortunately, I had a spare inner tube on hand and made the repair easily. The last step was to replace the fork seals and boots with new parts, so now it is a fully-functional SS125A.

The mufflers looked pretty solid at first, but then I noticed that the baffles were gone out of the back sides. The poor little bike seems to have had a rough life in the past 52 years in only 4k miles of travel under its own power. Such is often the fate of these little low-cost machines from the 1960s.

Exhibit 2. This 1971 SL100 that only had about 1300 miles on the odometer. It too, was supposedly a runner, but had been hard to start and keep running according to the seller. The first thing noticed was that there was about 1” of battery acid in the battery. These are battery-powered bikes, so if you don’t have a good battery, it is almost impossible to make them run.

Looking closer at the bike, I saw that the stem for the speedometer was broken off, so the meter was junk. The tires all appeared to be stock originals with little wear. Again, all the cables and levers needed replacing and the left side fork seal was weeping oil down the side of the fork slider. The fuel tank seemed to be relatively clean, but the petcock was rotting away. Both bikes needed new petcocks, which are available online for less than $10 each, but they are, of course, made in China.

The little plastic side covers, which fit all the SL100-125 models, have become scarce and even reproductions are priced over $100 each now. Both are missing from the bike. The headlight rim was taped to the headlight shell with electrical tape which is never a good sign. I ordered a reproduction shell from Thailand and that solved the problem, but the holes for the bolt spacers were too small. It came in black plastic, which I tried to paint with chrome paint, but it didn’t turn out very nice.

After going through the basic tune-up process, the bike initially started up and ran, backfiring back through the carburetor. The ignition points had closed down so the timing was about 5 degrees after TDC instead of 5 degrees BEFORE TDC. Opening the point gap brought the timing into specifications, but suddenly the bike wouldn’t restart despite having all the ingredients of spark, fuel, air and compression. Rechecking the timing with a test light, I discovered that the ignition switch was intermittent, so turning it ON didn’t mean that you had power to the coil in every instance. I installed an aftermarket ignition switch from a CB350, using just 2 of the leads and now the ignition is reliable.

Then engine sounded good once it was running, with no signs of smoke, but the initial ride around the block revealed noticeable primary gear whine in all gears. I drained the oil and pulled the clutch cover to check for obvious damage, but the only anomaly was a somewhat loose clutch basket on the input shaft. The primary gears are straight cut between the crankshaft and clutch basket, so as the load is put on the clutch, the gears fail to mesh squarely, probably causing the noises heard. Honda did upgrade the kickstarter shaft and a couple of gears in these engines, so this one probably needs the upgrade, but I am not going to do it.

The SL100 turned out to be “not on file” with DMV, so fresh paperwork was needed to get a title for the bike, plus a trip to CHP offices for them to do a bit more research on it. The SS125A had a title from Indiana, sold from a guy in Michigan and finally to the LA area seller that I got it from. He had paid some fees to get a title for it, but never got the engine numbers inspected to complete the task. The transaction was still in the DMV system, so I was able to get some of the current charges deducted from what he had paid previously.

ALERT for California residents! When I took both bikes down to DMV, for initial verification of the numbers, the bikes had a few parts missing (SL100-headlight and SS125A headlight, mufflers, tank and seat). I have taken partial bikes to them for the last 10 years without comment, as long as the engine was installed in the chassis when inspected. NOW, all of a sudden, DMV won’t inspect what they call incomplete bikes or “project bikes.” After wrangling with the two inspectors for a few minutes, I left the inspection lanes and took the paperwork inside for my desk appointment. The lady at the desk confirmed that CHP had come down on them for inspecting incomplete vehicles so they made up a new rule to conform to the edict. So, if you live in the Golden State, put all the pieces on your bike before you head down for a DMV or CHP inspection now.

Unfortunately, these little bikes can easily turn into a money pit, once you start replacing even the basic items, like cables, levers, petcock, battery, tires, and other consumables. You better be in love with your new tiddler project, if you plan to embark upon a restoration or even an extensive revival enough to get them fully functional and safe to ride again.

Bill “MrHonda” Silver 11-2019

Tuesday, October 1, 2019

EX-pectations: Kawasaki’s EX500 Ninja

I can’t say that I have really spent any time on one of Kawasaki’s long-running EX500 Ninja models, but one came available on Craigslist that I couldn’t pass up. These bikes were in production for 22 years, with few changes other than adding a rear disc brake, larger wheels and smoothed-out bodywork in 1994.

                                   2002 Kawasaki EX500, 49HP, redline 11k rpm, 426lbs wet.

Wikipedia overview shows:

The Kawasaki Ninja 500R is a Sport Bike with a 498 cc parallel-twin engine, part of the Ninja series of motorcycles manufactured by Kawasaki from 1987 to 2009, with a partial redesign in 1994.

Fuel capacity: 15.9 l (3.5 imp gal; 4.2 US gal)
Fuel consumption: 64.0 mpg‑US (3.68 L/100 km; 76.9 mpg‑imp)
Engine: 498 cc (30.4 cu in) liquid-cooled 4-stroke 8-valve DOHC parallel-twin
Power: 49.9 hp (37.2 kW) (rear wheel)
Seat height: 770 mm (30 in) (1987–1993); 775 mm (30.5 in) (1994–2009)
Torque: 30.9 lb⋅ft (41.9 N⋅m) (rear wheel)
Transmission: 6-speed constant mesh

This bike was a California-emission spec model, so equipped with a carbon canister and pulse air system. The history, from the seller, was that the bike was bought new in 2002 and the original owner had put about 500 miles on before tipping it over and scaring himself from riding it again. The bike sat until about 2012 when it was offered for sale. My seller picked it up, replaced a turn signal, added a new set of tires, a new battery and had the carbs cleaned. He rode it for a total of 2500 miles in the 7 years he owned it, then decided to make space in his garage for new endeavors.

Apart from a little scuff on the left front edge of the fairing and a few scratches on the mufflers and bodywork, the bike is quite nice. When fired up, the engine was clearly not running on the right side at idle. It seemed to run off-idle, but faltered when idling, even after a warm-up. Our shared opinions were that the idle jet was probably clogged up from lack of run time. Faced with having the carbs cleaned again in order to facilitate a good sale, the owner offered it to me for $200 less and I agreed to take it off his hands.

Once it arrived back home, the seat and tank were removed for carb removal/cleaning, however I noticed that there was an emissions vacuum line lying loose near the carburetor. Tracing it back to a junction, it appeared to need to be attached to an engine vacuum source. There are fittings on the intake manifold stubs for vacuum to the petcock on the left cylinder and the right side one was found to be unplugged which is where the vacuum line was supposed to be connected. It all made sense now that the engine wasn’t idling on that side due to a large vacuum leak! I did remove the carburetors and had to reset one of the float levels, but the jets and bowls were still clean, so the loose line was the actual culprit.

With the carbs reinstalled and all vacuum lines connected the bike fired up and ran well. The ergonomics are just about right for my dimensions and I was especially pleased to find out how easily this bike can be pulled onto the centerstand. Ah, the centerstand! This lost relic on many models now, is a treasured feature on street bikes, these days. It makes chain maintenance so much easier and gives the bike a different option to be parked, as well.

While on the centerstand, I turned the back wheel to check the chain slack and noticed that the rear hub has a cush-drive setup which seemed to be worn to me, with a noticeable amount of play in the back and forth directions. With only 3k miles on the bike, it seemed like an odd amount of wear. I ordered a new $60 damper for the wheel but was disappointed to find that a new damper had about the same amount of free play as the original. Apparently, age was not a factor in the old part, but an odd engineering oversight.

Between the gear lash in the transmission and the built-in slack from the rear hub, there is a bit of backlash when on and off the throttle that is attributed to both factors. There is an EX500 forum, with a resident guru who offers a few improvement bits and sage advice. His suggestion was to add in some pieces of an aluminum can to pack in around the damper, in order to tighten up the assembly. He also offers some rear suspension dog bones that raise the rear end about 1.5” in order to change the geometry enough to eliminate some odd handling quirks in these models. However, jacking up the rear end negates the function of the center and side stands, without carrying some stand assistance pieces onboard. Carrying around a 2x4” board in your backpack might be an option for some, but I would seek other options, personally.

I noticed that when I reinstalled the rear wheel, the right side axle adjuster tended to squirm around when the axle nut was tightened. The only way around it was to tighten the axle into the nut with the provided tool kit wrench. Yes, these bikes do seem to have a few quirks, despite their lengthy development time. 

Closer inspection of the rear axle setup revealed that there was a gap between the rear caliper bracket and the inside of the swing arm as you go to tighten the axle nut down. I found a 1.5mm shim to slide into the space and that seemed to help out quite a bit. There’s no reason to be pinching in the ends of the swingarm just to tighten up the rear axle hardware. So far, the bike has been up to an indicated 95 mph with no problems in the handling department.

The other puzzling issue was that the rear brake pads were worn quite thin. I ordered some EBC pads online and they installed easily with 3x the thickness of the originals. The front pads still seemed to have decent amounts of material left, so I guess the previous owners were rear-brake oriented.

Overall, the bike is really pretty good. It has a few more rated horsepower than the manic CBR250R that I ride, but weighs about 75 lbs more in wet weight. Obviously, the 500 twin has more torque and is geared higher for more relaxed freeway cruising at half of the engine speeds as the 250-4. Both have been getting close to 60 mpg, so quite economical to own and enjoy.

                                      1988 CBR250R (18k redline, 45 HP, 350lbs wet)

The only Kawasaki motorcycles I have owned in the past were a 1984 GPZ550 and a trio of 2000-2001 W650 twins. They are solidly-built machines with numerous positive attributes. Even though it seems out of character for MrHonda to own bikes from the K-brand, I think it is healthy to sample and appreciate bikes from other makers, especially when they bring a strong sense of satisfaction to the riding experience.

Bill “MrHonda” Silver