Saturday, December 17, 2022

Frankenbike 4.0 revisited again...

Just when I thought we had a handle on the bike’s reliability, new problems surfaced. Jake reported that the bike died on him while driving back from a 20-mile ride. It blew the fuse and he attributed it to the 60/55-watt headlight that had been installed by the previous owner/builder. Fortunately, he had a spare fuse with him and was able to change it out and make it back home again. The battery kept going low and he had to take it to the local auto parts store to recharge it every few days while running with the lights OFF as much as possible.

I was back for my monthly chiro appointment, just down the street from where he’s been living; still in his dead Prius car next to the railroad tracks. I stopped by to check the bike out and we confirmed that the headlight H-4 bulb was too much for the charging system, then with the bike running, it was apparent that there was little or no output from the stator. In the back of my mind, I thought that I had a CB350 stator and a 35/35 H-4 bulb at home so developed a plan to come back and install them.

Honda’s later model stators run in oil and ones for 350-450 and even the 160s are similar in design, at least from a quick glance. They all have little pigtail wires for the nearby neutral switch and have a round plug that meets up with the wiring harness. It’s a 70-mile round trip from home, but the continuing problems with the bike spurred me to gather up my tools again and haul the critical parts back up to N. County to help keep this man on the road with something other than his beach bike.

I really don’t spend a lot of time with 350 twins, at least by choice, so wasn’t deeply familiar with the differences between the stators of that era. The one I had in the shop came to me years ago from an unknown source, but it tested out fine and I was confident that it would solve the problem. However, it wasn’t quite as easy as I had hoped…

I met Jake at his little camping spot where the bike had been used sparingly for the past few days. I leaned the bike over against my truck’s tailgate to keep the oil inside the engine once the stator and cover were removed. I had replaced the inner gasket previously and hoped that it was still intact when I removed the parts. Fortunately, it was still solid and was set aside while I removed the stator from the cover. I noticed that the stator had a burned spot at one of the coils and that was what was grounding the output. I pulled out the old one and went to install the replacement only to discover that while the OD and ID were correct and the wiring connectors were a match, the replacement stator was much thicker and all of the mounting holes were not threaded which was needed for the 350 covers. It looked like some longer bolts might secure it to the cover, so after a short walk to the local Auto-zone. That was a waste of effort as they didn’t carry any loose bolts of any kind in the store, so we moved the bike away from the truck with a rag in the engine case drain hole and drove to Home Depot for hardware.

I found some longer bolts and nuts/washers at the store and headed back to the bike, which was about 5 miles away. The bolts looked to work fine, but then when I tried to install the dyno cover, I discovered that the lack of threaded holes kept the cover from being installed! So, one more trip to Home Depot to get some oval screws for the cover and nuts lead me to assemble the whole cover together from the inside, so the next time there is a need for accessing the rotor for timing, etc. the whole assembly will have to be removed again. It’s a stop-gap repair for the moment and I still have no idea of what the stator actually came from originally, but in the end, we had a charging system that was building the 11 volt battery condition up past 12 volts with an increase in the RPMs.

We had changed out the headlight bulb already, but I went back into the headlight shell and jumpered the yellow and white/yellow wires from the headlight switch to kick in the extra AC lead power back to the rectifier/regulator unit and the test results were even better. What was envisioned as a 30-minute repair job ended about 3 hours later, but with a successful result. Checking eBay for stators, there were a number of correct ones available for less than $50, so we’ll grab a good one for the future and have it handy for any future repair moments.

The bike is now much happier to start up and run well now that there is a current of voltage feeding the battery. It’s hard to know what the next challenge will appear, but for the moment the bike resumes its transportation duties and gives Jake some new options for continuing his photography business. Hopefully, some new opportunities will arise to help him get back into stable housing and get his dead car repaired. He really has an amazingly positive outlook on life, despite all of his current woes.

I’ve certainly learned a lot more about the CB350 twins than I had imagined, but it all comes in handy at some time, especially in cases like this. Now, just what does that stator actually fit…..?

Bill Silver

aka MrHonda


Tragedy.. Frankenbike gets run over

Maybe it needs an exorcism or some kind of spell breaker, but only days after I was able to get the Frankenbike Honda 350 back on its feet, I got a call from the owner who said, “ The bike got run over by a Toyota Tundra while it was parked at a cafe on Hwy 101.”

                                            Frankenbike revealed... on the way home again.

As if the owner hadn’t suffered enough trials and tribulations in the past few months, this happens! The only bright spot is that the perpetrator was kind enough to stay put, offer his insurance and driver’s license, and then paid $325 to have the bike hauled 30 miles down the coast to me on a Friday evening. If we can keep the costs down to around $1000, then the driver won’t put it on his insurance. So, we’ll see about that...

The bike arrived in the dark on a big roll-back tow truck. The tow truck driver had to back off the rear brake adjuster nut so he could roll the bike as the brake pedal was solidly jammed up against the footpeg bracket. I got up on the bed, holding the bike upright while the driver loosened the tie-down straps. He lowered the bed down to the driveway and I backward rolled the bike down to the ground safely.

I rolled it up next to my daily-driver CB77 and threw a cover over it for the night. On Saturday morning, the extent of the damage was revealed… The centerstand foot was twisted completely under the bike and the brake pedal smashed against the footpeg. The front wheel and headlight were all out of alignment. Sometimes you can loosen the forks and reset the wheel alignment, but in this case the fork bridge was broken at one side, so that put an end to any adjustment attempt. The bike is a 1972 CB350 and all of those twins have rubber-mounted handlebar mounts which are positioned into the fork bridge. This bike had none of that and it took about 15 minutes of research online to determine that the fork bridge and steering stem were from a CB400F! That model is in high demand for restorers, so spare parts are in short supply. After some digging, I found an eBay seller who had the bridge and stem for sale for $100, plus $20 shipping.

The next thing was to track down a brake pedal and centerstand for the bike, which were normal CB350 parts. There are a lot of these bikes being parted out, so I picked out the best-looking ones and bought the pair for a little over $100. Then you wait…

I couldn’t really tear down the front end, until the centerstand arrived, so all work ceased after I had removed the centerstand and brake pedal earlier in the morning.

When the parts started to roll in, I was able to install the replacement centerstand which has a powerful return spring. That allowed me to put a jack beneath the engine on a frame mount and push the front end up enough to remove the wheel assembly and eventually replace the frayed rubber boots with a new pair that came from an eBay seller. Finally, after using the front axle bolt as a guide to even up both fork assemblies in the triple clamps, I was able to get the front wheel pointed in the right direction again.

As a side task, I ordered a set of OEM Honda carb slide needles to replace the aftermarket kit parts which actually separated in the carburetor while running. I re-routed the cables and pinched the cable holder brackets together just enough to get the cable adjusters to stay put.

The brake pedal installation was the next to last task but took some time as the pedal that was purchased for the bike differed from the one that was removed. I wound up on the bench grinder whittling off some excess metal that was hitting the frame and engine cases. The part number changed from the original 286 to a 317 code part in the later years. Another case of assuming that most of those chassis parts were all the same through the years is when you find out the hard way that they are not!

Eventually, all the damaged parts were replaced, the carbs remounted with upgraded needles, and all the electrical systems working apart from the turn signals. The bike fired up on the second kick and made the usual racket from the poorly baffled mufflers, so I didn’t run it through the neighborhood at the 6pm finish time. The next day I was scheduled for a doctor's appointment about 2/3 the way back to Leucadia where the owner lives, so I loaded up the bike and hauled it back to it came from, prior to the accident.

In the end, it is still a Frankenbike with poorly designed modifications that will slowly fail in time. But for the owner, it is basic transportation that he sorely missed for the 10 days that it was with me being mended as good as possible, given the time constraints and the limited budget allowed.

I probably haven’t heard the end of this bike’s story, but for now it is functional and doing the best it can, all things considered.

Bill Silver aka MrHonda


Wednesday, November 16, 2022

Kiss my Keyster goodbye…. the Frankenbike 350 story continues

I have commented on the quality of the Keyster brand of motorcycle carburetor kits for years now, and am joined by many others who have suffered from the lack of accuracy of their components. I generally spend my repair time with 250-305 twins, but occasionally I have to work on bikes from a later vintage, often times 350 twins and an array of four-cylinder models. The challenge is that Keyster is one of the few remaining companies that make an attempt at offering repair kits for vintage motorcycles of all brands. 

You would think that a company that goes to the trouble of manufacturing carb components would have the expertise in duplicating the original parts accurately, but that is often not the case. We have found that the slide needles for the CB77 kits are too rich for Super Hawks, but work okay for Scramblers, which use a different needle taper. Likewise, all of their bowl gaskets are too wide where they fit into the forward slot in the carb base and don’t take into account that there are two little bumps that need clearance.

In recent years, the kits for the 305 Dreams started coming with #130 main jets which are way too rich for a stock bike that came with #120 main jets from the factory. Every time someone contacts me about difficulties with plug fouling on a Dream, the first question from me is: Does it have a Keyster kit installed with a #130 main jet? Often, lately, that is the answer to the problem. Early Honda models have JIS thread pitch jets, so you can’t plug in the later versions which are ISO pitch now. One of my suppliers does supply JIS main jets, separately from whole kits.

Usually, the plan is to reuse any OEM hardware pieces like jets and needles. I have discovered that the dimensions of the Keyster float valves are a little off, as well, causing the need to bend the float tang excessively to get the float height to be correct.

If you read my recent blog post

which was supposed to have been published back in September, you can see what kinds of problems can occur when you are using aftermarket components, like Keyster carb kits. Well, the story didn’t end there after all.

After a few days of happy driving, the bike became difficult to start and would stall out after a few seconds. I shared as much guidance as I could over text messages with the owner, but despite his best efforts the bike refused to come alive again. Part of the difficulty is that the bike is 30 miles away in Leucadia near my sister’s home. I only go up there about once a month for my nearby chiropractor’s appointment so I had hoped to be able to resolve the problems via text messaging. This was not the case, but my next appointment came due so I packed up tools and equipment to do a house call after my appointment.

Having tools on hand proved fortunate as my chiropractor needed some carb cleaning work on his Vespa Scooter, so I was able to trade services and save $125 for the visit. After that work, I drove down the road to the awaiting CB350 Frankenbike and its frustrated owner. Let the fun begin again….

Checking for battery voltage first, I measured 12.4v so that was a good starting point. The bike would try to start, then die as soon as the throttle was turned at all. There was backfiring going on during the startup attempt too, so that is generally an air leak or incorrect ignition timing. It was apparent that the right side cylinder was misfiring and not really catching on, so I focused on that side first. 

One of the other problems facing the owner was that the throttle cables wouldn’t synch up properly, which was eventually resolved after the carb cable extension to the left side had slipped out of the junction, leaving uneven lengths. The aftermarket cables have big fat junctions, unlike the originals, which can get trapped beneath the fuel tanks when the tank is set back on its mounts. The second problem was that either the threads in the carburetor cable holders were stripped or the cable end dimensions were undersized so that you can’t tighten the cable adjusters onto the carburetors. After a lot of fiddling, I got them as close as possible to matching each other and left it at that.

With the point cover off, the left side points didn’t seem to be opening very far which resulted in retarded ignition timing. The point adjustment was all the way open and the point backing plate was rotated as far as it could go but still, the timing was 20 degrees retarded, which explained the backfiring on that side. Eventually, I had to bend the point base contact outwards to get some point gap established and corrected the ignition timing. The bike started up and kept running but the right side wasn’t taking the throttle off idle, but it was idling okay. I thought perhaps the carb diaphragm was damaged, so removed the carburetor and pulled the top off to inspect the diaphragm. It looked fine but THE SLIDE NEEDLE WAS SEPARATED AGAIN! I don’t think that Honda’s Keihin carburetor slide needles are made in two pieces, but these certainly were. I tried to crimp the end of the needle slightly to make an interference fit with the little top hat end and tapped it back together again. It seems to be secure for the moment, but I don’t trust it at all now.

The bike started back up and was running on both sides, but idle mixture settings were off specs and there was still hard starting and some backfiring going on. I hit the intake manifolds with a blast of brake cleaner which I had brought along and the RPMs jumped instantly. A closer look at the manifolds revealed that the paper gaskets that were supposed to seal the manifolds to the head were blown out causing a huge air leak. The nearby Auto-Zone was a source for a tiny $6 tube of high temp RTV gasket sealer and the manifolds were glued back onto the cylinder head, solving that problem.

I had been on the job for more than 2 hours, improvising repairs and troubleshooting but finally had a functioning motorcycle, at least at the moment. I feel like starting a GoFundMe page for my suffering friend who still is sleeping in his car, next to the railroad tracks, living day to day from his meager income from photography work in the local area. He goes out and shoots local surfers in action, plus has other photography gigs in the county, but it isn’t enough to really get him settled into an apartment where the mean rent prices are in the $2k range. Surprisingly, he’s adapted to his situation the best he can for now, with a hopeful attitude for future work and a warm spot to call his own. See his work at 

I’ve done what I can do for the Frankenbike 350 for now. It needs a whole host of OEM parts to get its reliability improved, but it is what it is at the moment.

Bill Silver aka MrHonda


Frankenbike Honda 350 twin…

I received a desperate call from a man who needed some electrical work done on his “CB350” as his Prius had just died after spending $2500 on new batteries. Apparently, a cooling hose leaked out all the coolant on the freeway and fried the gas engine. I am not sure if he had already owned the bike or bought it as a temporary solution to his transportation needs. Unfortunately, the bike began to blow the main fuse, then with help from semi-knowledgeable friends wound up with a new, aftermarket wiring harness installed but not fully completed.

Day ONE--- Delivery

I didn’t ask all the right questions like, “Is it a stock CB350?” etc. so I agreed to have a look at it. After finally rounding up a friend and his pickup truck to haul it 35 miles down the coast, it arrived late on a Thursday… Arrgh! The bike was someone’s version of a “cafe bike” transformation, which still had the stock tank and frame, but the rest was non-stock, to say the least.

The fork tubes were shoved up in the triple clamps about 2” compressing the fork boots down. There were no fenders, front or rear. The stock seat pan was reupholstered and beneath it a tiny 4 amp battery was strapped down to the battery box. I was puzzled as to where the starter cable was hiding but then noticed that there was no electric starter on the front of the engine! It was an SL350 engine swapped into the CB chassis! The carbs were still the stock CB350 CV carb set, however.

The later SL350 engines have a special cylinder head with small ports and a pair of 24mm carburetors to enhance the low-speed torque and power for off-roading, but probably a complete mismatch for the 32mm CB carbs and their calibration. Oh, of course, there was set of noisy-looking aftermarket mufflers attached to the header pipes, which affects the carburetor calibrations, as well.

The “cafe” handlebars were the drop-down kind but all of the original length cables, normally on a set of much higher handlebars, were still in place looped around and around the front forks and handlebars. The clutch cable jutted out on the left side and was zip tied to a too-long spark plug wire, both hanging out in space. The owner brought a box of spares including another set of stock cables, which were useless on this application. There was a tiny aftermarket speedometer hooked up and a large H4 headlight mounted up front. The turn signals were tiny aftermarket units, as well. Pretty much anything that came from the factory was no longer present.

The fuel lines were that colored plastic stuff, that was then zip-tied to the fuel fittings. I had to drain the fuel tank through one of the fuel lines from the Chinese petcock which has reversed markings for the On-OFF-Reserve from normal. I barely got one of the lines off, but the back one pulled the fuel fitting out of the petcock body. I hate this stuff!

Looking over the electrical connections, it appeared that the condensers and coil wiring was incorrect, but all of the wiring colors are different on the aftermarket harnesses, so a 12 v test light will get a workout as I sort through the connections. An aftermarket rectifier-regulator was installed but the wiring colors don’t seem to match up.

I went online and quickly ordered a set of short cables from along with 5 feet of 5.5mm Honda fuel line, with payment for 2-day delivery which cost $37!

Day TWO- Investigation.

I had a leftover Li-Ion battery that was larger than the one in the bike and might work out better for this bike. Even though it showed fully charged after a few hours, the Li-Ion battery failed the self-test, so the little 4 amp battery was charged overnight and reinstalled. Then the fun began…

Turning the ignition switch to ON blew the 15amp fuse. Looking over the wiring to the points and condenser, it appeared to be miswired, so after reconnecting the condenser, coils and points, the switch was turned ON again… and another blown fuse. I did an ohm test on each coil and the left side which was a made-in-China Tec coil had shorted out to .6 ohms. The opposite coil was about 3.8 ohms. In the box, of spare bits was another coil, which tested out okay and when installed the fuse stayed intact. One small step towards success. Unfortunately, the replacement wiring harness had wire colors unknown to Honda’s engineers, so it took time and getting a copy of the revised wiring harness from to help guide me through the process, one wire at a time.

Using a 12v test light, I was able to probe various wires for power or ground and eventually got everything that was supposed to be connected… connected! Power ON showed headlight (both beams), tail and brake light functions, ignition power to the points and power to the rectifier/regulator. I tried to kickstart the bike, but it didn’t give any signs of wanting to run. Compression checks revealed about 150 psi on each side, but the engine sounded noisy when kicking it over.

Putting a wrench on the rotor and turning the engine forward/reverse demonstrated some slack in the camchain, which was reduced with a camchain tensioner adjustment. The tappet covers were almost unmoveable except for my adjustable Sears 6 point 12” long wrench which finally broke them loose without breaking anything. As suspected the tappet clearances were WAY off. I noticed that the little index marks for the ends of the rocker arm adjusters were not all in the usual 4 and 8 o’clock positions, so that was all reset.

Next step was to tear the 722A carbs off and see how they were doing inside. The first thing was that there was a lot of unmarked parts indicating some off-brake carb kit installation. The float levels were in the 19-21mm settings, which is fine for early carbs but doesn’t match the 26mm suggested settings from Honda. After the floats were reset, the carb tops were removed to check the condition of the slide diaphragms. The left side had the usual little locating tab, but the right side did not. When the slide was inspected the non-adjustable needle had separated and the top was left inside the slide body, while the rest of the needle was sitting in the needle jet inside the carb throat. I didn’t realize that these needles were made in 2 pieces! I tapped the top back on the needle portion and hoped for the best.

When the right side carb was inspected, it had an incorrect float level setting as noted above, with a non-indexed diaphragm. The needle was also dislodged, but not separated. Whoever put the needle back into the slide didn’t secure the wire clip that holds everything down in place, so that needle was jumping around too. The owner said that the bike had been running previously, but not well. Duh! I am surprised that it ran at all. With carbs done, I awaited the new short cable set from to come so I could install the new throttle cable, along with the clutch and front brake cables of a more appropriate length.

Day THREE… updates

The Priority Express mailing of the cables failed to arrive in the 2-day period. Ordered on Friday, they finally landed on Monday, which normally the regular Priority Mail shipping ($15) would have sufficed. contacted USPS and actually got a refund for failed 2-day delivery. The old cables were already disconnected at the handlebars, but not without more difficulties. The cable adjusters were somewhat corroded into the lever mounts and the ends of the cables were corroded as well. Prying them apart finally released the cable ends and the adjusters went into some Metal Rescue for de-rusting. With non-standard handlebars, the best cable routing has to be determined by trying various routes to allow the cables to move properly and not be pinched by the fuel tank. The clutch cable goes into the left side cover where it connects to the clutch lifter hardware. Finding the right path took a few tries, but eventually raising the handlebar angles helped make it all fit.

The bike was fired up, finally, with way too loud mufflers blasting my quiet neighborhood. The bike ran unevenly but finally went down the road under its own power. Kickstarting was kind of random when the key was turned on, eventually, that problem was traced to an erratic aftermarket ignition switch function. I finally had to “test” the switch with the horn button to see if it actually had turned ON or not. I dismantled the switch and smoothed out the contact plate, but it still seemed to have some dysfunctional moments.

Day FOUR… too much drama

I told the owner that I thought the bike was ready to ride after about 6 hours of labor and adjustments of the engine and fuel system. I also had to seal up the leading top edge of the fuel tank with some tank sealer as there was a fuel leak right at the seam. The owner had to come down to Spring Valley on the Coaster train and then on a bus to my neighborhood. I had just returned from appointments, so the timing was about right. He appreciated all the work that I had done and wanted to add value to the transaction by shooting some photos of me and my NT650 in action and in some scenic spots nearby.

We rode out to Mt. Helix which is a panoramic viewpoint in the La Mesa area. The bike seemed to run okay as he trailed me on the Hawk GT. We took some photos around the top, then when we went to leave the bike wouldn’t start back up. It appeared like the left coil wasn’t firing again and it just wouldn’t light up on the right side. I rode back home, got my Tacoma, and returned to load up the 350 and bring it back home for diagnosis.

It appeared like the left side coil still wasn’t firing properly. I replaced it with another spare from the extras in his parts box. The bike started up and I drove it over to the 7-11 to fill up the tank for the journey home. The bike started dropping one cylinder again, but this time it was the right side! I would not fire up again, so the owner was summoned to bring my truck over, and pick me up so I could return home and get the ramp and tie-downs again. We were only about ¼ mile from home, but we were losing light and the owner had been planning to make a coastal journey back home which was looking less and less likely.

Troubleshooting the bike, I finally tested the battery voltage which had dropped to 8 volts with key OFF and 5 with key ON. Okay, a combination of a failed charging system and perhaps an undersized battery were the current causes of failure to keep the bike alive. I wound up taking my owner friend back to the train station in downtown San Diego, which is a 14-mile drive, one-way, and promised to get to the bottom of this problem the next day. I had to take responsibility for the fact that I never checked the charging system output during all of the running and electrical repair work.

Day FIVE… Battery hunting

Calling the local Honda dealership, it seems that the correct battery for an electric start CB350 was NLA at any of the other motorcycle dealers in the SD region! I called Interstate battery and they said the battery was back-ordered. I finally found a battery store out in Santee (12 miles away), that had two in stock! I made the trek out to the store and secured the new battery, turning in the old 4 amp battery and the leftover Li-Ion spare as well.

Dropping the already-charged battery into the bike, I noticed that the static voltage was about 12.5. With the key ON, it dropped to 12.25, which is pretty normal. The bike sputtered back to life again now with full voltage to the coils and cleared off some of the unburnt fuel in the cylinders and on the plug tips. Revving the engine up, the voltage failed to increase, so there was more hunting to do.

I had to remove the left carburetor, which is easy with no air filter box to have to remove. This gave me access to the electrical plug that connects the stator windings to the main wiring harness. Pulling the plug apart, revealed that two of the female connector pins had pushed out of the connector, thus no AC power going to the reg/rectifier. Finally, the last smoking gun had been discovered. Reassembled again, the voltage increased to nearly 13 volts with no lights on and held steady around 12.5 with the lights back ON again. Another run down my test circuit was successful with the engine pulling towards redline and running well on both sides. Repairs finally completed… or not!

The engine was drooling oil down from the dyno cover side gasket. From the appearances, I would guess that someone made a gasket to fit, as most CB350 gasket kits would have supplied a dyno cover gasket that incorporated the electric starter function which this bike did not have. Digging through a pile of misc gasket sets, I discovered what appeared to be the correct gasket. That will be a job for the next day.


To prevent oil loss, the bike was leaned up against a wall so the dyno cover gasket could be changed out. The rear engine cover needs to be removed first, but that only happens after the shift lever is removed, the footpeg bolts loosened up, and then the cover was

removed. The gasket replacement was successful and the bike was sent back home for local transportation needs. I can only hope that it continues to function given the difficulties that were presented with this Frankenbike 350.
Factory AHMC photo of what the bike looked like originally

Bill Silver aka MrHonda

Sept 2022

Friday, November 4, 2022

MrHonda takes in another stray…. Honda CB750 Cafe Racer #2 of 2 (part two)

 Deja Voodoo…. The evil twin takes the place of the Orange CB750

I dropped off the Orange CB750 Cafe bike to the owner, after more than a week’s worth of dismantling, ordering parts, cleaning, adjusting and doing a deep dive into what I had to work with. The owner was thrilled to have it back, but then pleaded his case about having me “take a look” at his black CB750 which is a mismatch of K0 engine parts, an unknown frame, custom 4-into-4 exhaust pipes, Clubman bars, and a set of pod-filtered K2-ish carburetors.

The quick rundown was that he was putting a battery in it every few months and the bike kept dying due to charging system issues. Beyond that, the custom exhaust “mufflers” (there are some baffles inside but they don’t do much) were hitting the end of the swing arm on the #2 pipe, and the side stand was wedged in between the #1 and #2 pipes so that the shortened stand arm was getting stuck between the mufflers and didn’t fully retract which was causing grounding issues on left-hand turns.

Also mentioned was that the engine was an 836 big-bore motor with “low compression” in a few cylinders. There was a misfire in #3 cylinder and rattling noises coming from the engine cylinders as well as a very noisy clutch.

We loaded the bike up and I drove it back to Casa de Honda for a going over. With the tank removed and the side cover removed, I had access to a Medusa-like nest of wires that were zip-tied and taped up that were going every which way. The first tests are on the stator and field coil with the harness lead disconnected and the VOM first checking continuity with the buzzer function. All three yellow wires were connected and not grounded. The field coil checked out okay, with a 7.9 ohm resistance value. The bike had already had a solid-state regulator-rectifier installed which was a Hail Mary attempt at solving the charging system issues. Working backward from the connector to the Reg/Rec unit into the harness I discovered that one of the three yellow wires wasn’t making a connection down to the control unit. Unwrapping old, oily electrical tape and cutting a few zip-ties got me to a section of the harness that had been zip-tied to the carburetor throttle cable bracket. Pulling it away and unwrapping the wiring revealed a separate yellow wire that was smashed up against the carb bracket and the friction and vibration had worked the wire into two ends. I cut back the ends and crimped a butt connector into the harness wire. Checking with the VOM again, I had continuity all the way through the three stator wires.

I fired up the bike with the gas leftover in the carburetors and watched as the voltage increased as the revs built up. So far, so good.

The compression test came back with 140 psi in #4, 160 psi in #3, 190 psi in #2 and nearly 200 psi in #1. The high compression numbers are consistent with the 836 big bore piston kit, but the two lower numbers, side by side, often indicates a blown head gasket between the two cylinders. The #3 spark plug came out with a much different color than the other three, which indicated either a lean condition or has something to do with the blown gasket.

This bike had the same removable frame section kit installed like the Orange bike, so with that frame piece out of the way, the tappet cover could be removed for a quick look at the overall condition of the engine internals. Everything was pretty clean and well lubricated but when the engine was turned to 1-4 TDC for a valve clearance check, most of the “loose” ones were too tight, including the intake valve of #3 cylinder.

With the difference in the cylinder pressures so great, it was time to pull it apart and find out what was wrong with it. Wrestling the exhaust system off was the first challenge as the original header pipes had somewhat baffled muffler bodies welded on, but only the outboard mufflers had brackets to the frame. The inboard mufflers were attached to the frame with radiator clamps. The #2 muffler came off and had a big hole worn through it from where it was rubbing against the sidestand/bracket area. That required a trip down to my friend, Rob North, for some creative clearance work building a little box into the muffler body.

The carburetors were a chore to remove from the manifold stubs, as the heat and age had hardened them into solid blocks of plastic. I had to use a Dremel cutoff wheel to remove the manifolds from the cylinder head. A check of the carb bank showed float levels a bit low, but #140 main jets installed. That is pretty big for most applications, but the spark plugs seemed to be reading okay.

With the camshaft disconnected and removed, the zillion head nuts and various bolts for the rocker arm stands were all extracted, but I could feel that there were stripped 6mm bolt holes in the head. Two of the bolts were not installed at all, owing to the fact that the rocker box gasket holes were out of place, so they decided to just leave them out.

The head was lifted off and the condition of the head gasket seemed to be fine. It definitely was a big bore motor, so a Cometic special gasket was sourced from an eBay seller. The bore spacing on these engines are pretty wide, so the chance of a gasket blowing out between cylinders seems remote. That left the valves to be inspected. All of the valve heads were marked “Made in Japan” which indicates that they are NOT OEM parts. The intake valves wouldn’t come out of the guides until I filed down the ridges that had formed around the valve keeper areas. The valves and seats were making good clean contact, so that left the exhaust valves to be the source of low compression. Sure enough, the exhaust valve seats in the head looked pretty good, but all of the exhaust valve faces were pitted all the way around and all were exactly the same. Honda wants $70+ each for an exhaust valve, so I tapped into my account at and ordered up a whole set of valves (same brand), plus a set of reproduction intake manifolds and a few spare bolts/nuts for about $250 delivered from Holland.

I had to reorder a set of Heli-coil repair inserts to repair all of the damaged 6mm holes. An eBay seller has a nice kit for less than $20, with 25 inserts, plus all the installation tools. After de-greasing the head and installing all the inserts, it was ready for new valves and stem seals. I bought a different brand of gasket set (NE) from an eBay seller and instead of ill-fitting gaskets, I was dismayed to discover that the “complete kit” was missing all 6 of the rubber seals, the two small o-rings for the rocker stand feeds and the 8 sleeve rubbers that are used on the later engines. The kit was labeled 1969-76, but was sorely lacking in content. I complained to the seller and was refunded $11. It’s another case of wondering why some company would go to the trouble to make a gasket set and get it all wrong….???

After waiting for all the incoming parts orders, the reassembly commenced. The camchain was a little worn, so you can see it moving a bit on the sprocket. Camchains on 750s are the same length as those on the 250-305, 350 engines, but they are endless instead of having a master link. To replace the camchain requires a full tear-down of the engine so you can loop the camchain over the crankshaft sprocket.

Initially, I missed the cam timing by one tooth and a quick check of the compression readings came up in the 120 psi range! Shifting it back to where it was supposed to be yielded 170 psi readings across the board. Slowly, the rest of the top end was reassembled and buttoned up. The new intake manifolds were almost as hard as the old ones. It took about a half hour of shifting them around and pushing the carbs on with a pry bar to get them seated and clamped down correctly.

Wrestling the exhaust pipes back onto the chassis was another twenty-minute task, as all the clamp bolts were rusted and needed to be replaced and the pipes positioned correctly. The inboard pipes were reattached with hose clamps again as there were no other options. Working on these “custom” bikes has worn me out with endless tasks to make the parts go back onto the bike working with someone else’s ideas of what is “cool” and custom.

I fired the engine up on a remote bottle feed to see how it would run. The mufflers appear to have baffles on the end, but they are basically straight-through, so quite loud. I’m sure that my neighbors will be pleased not to hear that roar for too long.

The fuel lines cracked when I pulled on them to hook up the petcock fittings, so those needed to be replaced with 5.5mm Honda hoses. The rear brake pedal hits the muffler unless you position it just right and adjust the brake rod to find a happy place between being too high and hitting the muffler below.

Eventually, it all came together and it went out for a test run around town. The bike has a bit of a flat spot at 4k then comes alive after that. Idle is good but there is a little backfiring happening in that #3 cylinder that must be carb related, as the manifolds were all changed and the jetting is the same as all the other cylinders. 

With some miles run in with the new owner, we'll see if it heals itself or needs a round of carb work which is quite time-consuming with the later carb sets. I dropped it back off to the owner and he's happy to have both bikes back and running with a lot fewer problems and more understanding of what they need and perhaps a deeper knowledge of what to look out for in future purchases.

Bill Silver aka MrHonda


What this bike would have looked like from the factory.

MrHonda takes in another stray…. Honda CB750 Cafe Racer #1 of 2 (part one)

What it looked like new from the factory.

Having just cleared the backlog of bike repairs, a customer referral caused me to bring home another bike for a “minor” electrical repair. The 2-3 cylinders were dropping out intermittently after the bike had been at a shop for 8 months for a top-end overhaul. Even with an upgrade to Dyna Ignition and Coils, the bike continued to quit on the middle two cylinders.

It seemed like a repair that I probably could have done in the man’s garage, but time was tight and it looked like there was more to do than to hunt down the electrical gremlins. So, it was loaded into the Tacoma for the 30-mile drive home and unloaded the next morning for a closer view. The bike had had a rattle can silver paint job on the frame, some Clubman handlebars, a very fat 120/90-18 rear tire, a drive chain way too tight, oil leaking from around the left side of the cylinder head, an oil pressure warning light that turned on when the high beam was selected and a few other issues. The carbs were fitted with little cheap cone-shaped pod filters and the rubber sealing boots for the top of the slides were all MIA.

Fortunately, the dead ignition symptom was still present, so after the fuel tank was removed, access to the ignition system connectors was easily performed and what seemed to be a decent installation turned out to have a pair of undersized bullet connectors that were floating around inside the insulated ends. I replaced the bullet ends with larger sized versions and tested the system again. After clearing out some leftover un-burned fuel in the dead cylinders, they came back to life and the engine started sounding a whole lot more like a normal CB750. Mission accomplished… or not!

The owner was impressed with my findings and wanted me to work on his OTHER CB750 after I was done with this orange one, however there was a pressing need to fix the oil leaks that appeared to be from the newly installed head gasket. The saving grace for this particular bike is that the frame sections above the head were cut out and then then special tubing splices were installed to reunite the frame section after the gasket repair. I probably wouldn’t have even taken on the job if I had to pull the heavy lump of a motor out of the frame. With the owner’s permission I ordered a set of top end gaskets from my friends at and tracked down a $90 set of the OEM carb boots for the carburetor tops.

There was a lot of fiddling to get the frame section loose. The fasteners were all SAE nuts and bolts and all the splices had to be slid aside to get the frame piece out of the chassis. Eventually, it all came apart and I was able to begin removing the top end components. The top cylinder head cover was all held down with stainless steel Allen bolts, some of which came out with some difficulty. This is usually an indication that the threaded holes are damaged, which isn’t unusual for a lot of the Honda Fours from the 1970s. There are a lot of little nuts, washers, bolts and screws that hold the top end together and they all have to be dismantled in a certain sequence. I removed the one accessible cam-sprocket bolt which holds the cam-sprocket to the camshaft, then kept working on the other parts. Suddenly, I noticed that the cam-sprocket had fallen off the camshaft when I had brushed up against it! There was NO second bolt and the one I removed was not very tight. Looking around the base of the valves, I spied the missing cam-sprocket bolt all mangled and unusable. There was a random piece of aluminum that had broken away from somewhere but I didn’t see the source right away.

Eventually, the cylinder head was ready for removal and cleaning. The tops of the pistons were barely coated with some burned oil carbon deposits, so it hadn’t been run for too many miles. In checking all of the 6mm bolt holes in the head, the first thing I did was to flush the holes out with brake cleaner and I was surprised to see a lot of old oil deposits that had been lurking deep down in the holes. The contamination inside the holes can cause the ends of the bolts to bottom out inside the hole and that in turn, damages the threads. Eventually, I wound up repairing seven 6mm holes with Heli-Coil thread repairs.

After prepping the head for re installation, I loosened up the drive chain so it had some slack to it and then spent another 20 minutes dismantling the back of the speedometer to access the various light bulb sockets and then determine which ones needed to go where. I checked the wiring inside the headlight shell and found a lot of either disconnected wires or ones that didn’t match up to normal OEM Honda wire colors. Eventually, I sorted them all out so that the neutral light came on in the green lens and the oil pressure light came on behind the red lens.

The gasket set which was ordered on a Friday morning, went out to the post office that day and landed in the mailbox on Saturday afternoon’s mail. I was all ready to open the kit and start installing new gaskets and o-rings from the D&K branded gasket kit. I had a bad experience with a CB650 gasket kit from these makers a few years back and hoped that those problems had been long-solved.

Sadly, the CB750 head gasket had numerous mismatches where the 6mm bolt holes were supposed to line up It was just off here and there, but clearly could not be used as-is. I used a rotary file tip to enlarge the holes in the correct direction so that bolts could be installed once the cylinder head was dropped down in place. This probably took an additional 30 minutes of test fitting and whittling on the gasket, which can be easily damaged, but finally I felt like it was going to work.

Bolt by bolt, I installed the four external 6mm bolts which are exposed to the outside, then the front and rear bolts in the center of the head, followed by the all the washers and nuts on the cylinder studs. The sealing plugs were a nice tight fit, but I glued them in place with Gasgacinch gasket adhesive. The old sealing plugs were about 1mm thinner and not a tight fit around the edges of the holes where they are fitted. It appeared that the last mechanic had chosen to reuse most of the rubber parts and all of them had flattened out over the years.

With the head bolted down and the cam towers installed, the rest of the process is getting the cam timing correct and getting the rocker arms and rocker arm shafts all installed, followed by a valve adjustment. I had to order new cam-sprocket bolts, which are 7mm, from an eBay seller. Those came down in 3 days from the Delaware, and were installed with a dab of blue Lock-tite to ensure that they don’t try to back out once more.

It takes a bit of time to dismantle the carb tops and linkage bits to refit the rubber sealing boots. They are not really critical for operation, but keeps corrosion and dirt from damaging the adjustment nuts. They are fussy to install into the grooves of the adjuster sleeves and you have to pull them away when you are syncing the carburetors.

Slowly, all the hardware and brackets were all reinstalled and the bike readied for a start-up with a newly sealed cylinder head. There was a little hiccup with installing the new camshaft sprocket bolts. Despite looking at the threads of the side where the bolt flew out, the new bolt didn’t want to start into the hole. This was one of the last steps before putting the top cover on, so everything was in place like rocker arms, etc. Fortunately, my aged MAC tap and die set had a 7x1.0mm tap in the set, which was never used in the last 30 years. I rolled the engine over so that there was a little bit of room to insert the tap and I turned it over with a 7mm open-end wrench and was able to clean the threads up with everything still in place.

I had set the top cylinder head cover aside when it was dismantled, and when I grabbed it for some cleaning up, I finally noticed a quarter-sized hole that was punched through when the bolt made its exit. Fortunately, a friend in Lakeside (16 miles away) was the CB750 whisperer for many years and had a spare solid cover available. It was a bit scruffy, but I saw that he had a bead blaster in his shop. He offered to let me use it and that made the price more palatable. Once home, a good wash job and some aluminum paint made it look pretty good.

The reassembly process continued with the carburetors and wrestling the 4:1 exhaust system back onto the spigots and all clamped down. The fuel tank was installed and fuel lines were attached (OEM 5.5mm hose not that plastic crap). The bike fired up almost immediately and sounded like it was hitting on all four cylinders evenly. After a warm-up, I took it out for my local test run for about 5 minutes, then returned to check for leaks and problems. Some of the leftover oil and grease had heated up and was drooling down the engine surfaces, but there were no active leaks on the top end now. Of course, after the second good run on the freeway, oil leaks surfaced from elsewhere.

The engine dyno and shifter cover gaskets appeared to be weeping and then there was some oil that was coming from around the countershaft sprocket. With the cover removed, there was a shiny oily patch in front of the countershaft sprocket/chain. Closer inspection revealed some chain marks on the engine case, where the drive chain had been run too loose and it was lifting off of the sprocket and rubbing against the engine case, leaving a couple of wear mark tracks. That required removal of the chain and countershaft sprocket, cleaning the engine case carefully, and then mixing up a batch of JB-Weld to patch up the damaged area.

The gasket and seal kits came on the same day, so with some careful cleaning and a little bit of Gasgacinch sealer to help the sealing process, the gaskets were installed successfully. I had to add some extra sealer around the rubber grommet for the stator winding wires, but it looks like it is ready to return back to the owner.

I suppose the next task will be to look over his other CB750…..

Bill Silver

aka MrHonda


Saturday, August 20, 2022

1965 Honda CP77- the P stands for project

One of the most confusing Honda Super Hawk models is the model designated CP77. Unfortunately, Honda made factory Police bikes with CP77 in the serial numbers, as well, but they are a completely different model to the non-Police bike CP77.

                                                    CP77 is completed and running again.

The short version of the model is that it is a chassis-modified CB77 305 Super Hawk with the same powerplant and suspension as the rest of the CB77 editions. The difference in the chassis configurations are the high handlebars, winkers (turn signals), a dual-element headlight, the early 1961 style tail light, non-folding footpegs, Dream 300 tank badges and generally, a sidestand was fitted.

See: for the whole parts list and CP-specific part numbers.

I had a preview of this bike when it was shared on an eBay auction. It didn’t look that bad in the photos, but the bike was located in N.Cal and with shipping, it didn’t really pencil out for me, knowing that the engine was seized, as described by the seller. When I put up a nominal bid the seller saw my name and messaged back to me: “If anyone can fix this bike, it’s YOU!” which was a kind thought, but after more consideration I let further bids take over and forgot about it.

Well, as things go in my life, my local friend Don Ince happened to be friends with the ultimate buyer who asked if I would take a shot at rebuilding the engine for him. I agreed to put it into the queue and after a few weeks, Don brought it by the house and dropped it off in the driveway. ARRGH! With only 1600 miles showing on the speedometer, the bike was covered with rust and corrosion on just about every metal surface. White fuzz was all over the engine surfaces, rust on the brake hardware (brake cams were stuck, of course), and it was dirty from top to bottom. The CA license plate had 1977 tags in the corner. An aftermarket rear rack complicated seat removal and will be discarded. The tires were both original and everything on the bike appeared to be as from the factory, but having spent way too much time in a moist environment, unprotected from the elements.

Starting with the fuel tank, a big set of Channel-Lock pliers were needed to remove the gas cap, which was coated with rust on the inner face, plus the petcock came out coated with rust, as well. I am not even going to mess with this one, so it goes to the local radiator shop for cleaning and a Red-Cote coating. They charge $180 for the service and it is worth it to me to just get it done rather than sit with it for a few days while it gets de-rusted and then coated with Caswell, which is my preferred product for sealing fuel tanks. There is so much going on in the way of needed repairs that I’ll gladly farm out the gas tank cleaning.

It took about 2 hours to get the engine extracted from the chassis. Someone had bodged up installing some small coils that had attached condensers to the brackets. I didn’t recognize the coil sets, so they must be from some other brand of a Japanese bike. The coils each had individual condensers attached.

The air filter tubes just broke into pieces when removed and the air filters were all originals with 60 years of aging. All of those will be replaced from Tim McDowell’s site.

I wrestled the 115 lb lump onto the workbench and carefully used my impact driver to loosen and extract all of the cylinder head screws for the tach drive and point side cover. Removing the top cylinder head cover, I was relieved to see that the camshaft and rockers and even the valve springs were still quite clean and shiny, owing to the low miles of use on the engine. The cam chain link was just a few inches down inside the head and I was able to knock the side plate clip loose and detach the camchain from the sprocket without having to cut it.

Once the head was off, it was evident that water had worked its way into the right side intake port and rusted the piston into the cylinder liner. The left side showed water damage but looked better than the right side.

Tearing down stuck 250-305 engines is always a challenge, but usually successful. The usual water in one cylinder causes the rings to get glued into the ring lands and then rusted into the cylinder walls. After overnight soaking in penetrating oil, I washed it all off and layered on some metal prep, let it sit awhile, and then used my steering wheel puller as a pusher and was able to very slowly drive the right side piston down from near TDC to almost the bottom of the cylinder. Fortunately, the left side wasn't really stuck, so it moved up as the right went down. I took the wrist pin out of the left side to free up the cylinders and then pulled the cylinder block up and away from the cases. The piston was STILL dragging in the bore, so I used an air hammer to push it out while pulling up on the block. So, I thought that was the end of the hard work...... As I removed the clutch and primary nut, the clutch basket wouldn't budge! I have never seen a problem like this but the basket was seized on the main shaft! After a lot of prying unsuccessfully, I discovered a giant 3-jaw puller in my toolbox and was able to wrap it around the clutch basket and primary chain and slowly pull the basket off the end of the main shaft. Has anyone else ever seen this kind of problem before? It's a new one for me.

Once the engine was completely torn down, the time-consuming task is to get the dirt, grease, gasket material, case sealant, and corrosion out of the nooks and crannies of the intricately designed die-cast cases. I started with paint thinner to get through the worst of the greasy parts, then poured straight metal prep (phosphoric acid) all over the outside, and then scrubbed with brushes and small tools to get into places that had collected impacted dirt and leftover grease. A rinse with water to neutralize the acid, left the remaining scale in many spots so a round of drill-motor powered brass brushes and scrapers removed more of the remaining scale and grit, then the second round of acid bath foamed up where the remaining scale was, then given a final bath and then blow-dry with compressed air. At that point the cases got a coat of Duplicolor Cast Coat Aluminum paint to give the surfaces a little bit of shine. The engine case cleaning and painting process took well over two hours alone.

Beginning the engine assembly requires a close look at all of the parts to ensure full function at start-up time. The crankshaft was dropped back in and the bearings aligned on the knock pins. I had checked the gear dog engagement when the cases were first split and I could see that the transmission would need some offset gear cotters to remedy the lack of engagement on both shafts. Again, the engine only had 1600 miles on it from new, so remarkably the engine internals were still bright and shiny.

I dug through a pile of old transmission parts to find the correct main shaft to replace the one which had the clutch basket seized up on it. The first one I grabbed and cleaned up turned out to be from a Dream, so the teeth count was incorrect. A second one had worn teeth and a third one turned out to be correct for the CB engine. The shift drum and forks were reinstalled and the gear dog engagement was checked and found to be correct once the offset cotters were installed.

The bottom engine case had very little in the way of debris and the usual goo that is always present at the bottom of the engine from oil additives that fall out of suspension and sink to the bottom, so cleaning up there took no time at all. Even the oil pump screen was bright and shiny. In the end, the bike was no doubt put aside when the clutch basket seized on the main shaft, causing major operational problems. The black CA license plate carried 1977 tags, denoting its last year of use.

The nice-looking, but damaged clutch basket could not be saved. Running a hone on the inside of the mounting sleeve only revealed further damage to the machined hole. Not only were there circular rings of damage out at the edges, but two deep scrapes were noted that must have come from the factory assembly process. My choice of clutch baskets were clean, but non-cushioned types from the earlier models. The clutch plate set, expected to be stuck together after forty five years, slipped out looking new! It was one of the last 6 plate clutch packs used, before Honda upgraded to the 5 plate type.

All of the fasteners needed a bath in Metal Rescue and a turn at the wire wheel for final cleaning. I purchased an engine screw kit from Tim McDowell, in addition to all the air filter parts, gaskets, and other misc items that totaled about $500. New carb kits and a petcock repair kit were part of the package and fortunately, the carburetor slides came out without too much pulling. The petcock tube was covered in rust and the body will need a full cleaning and perhaps replacement of the brass tube.

I love the new MotoBatt batteries which are sealed AGM types, so no more acid stains in the future. The whole ignition switch had been punched out, leaving the back side of the switch with the wiring connectors. Like so many other components now, a NOS ignition switch is a rare find and the prices are in the $200-250 range now for those which are still on the market.

Even finding tires of the right size is becoming difficult. Lately, I have been using 3.00x18 tires on both ends, versus a 2.75 front. The original ribbed front designs are pretty much extinct now. With the wheels off for new tires, the related task is to disassemble the brake plates and clean/lubricate the brake cams which the brake shoes are operated from. Honda staked the outer nuts that hold the brake anchor pins, so they need to be ground down a bit to allow the nuts to be removed. I ran a tap down the brake plate holes and a die on the pivot bolts to clean up the threads for reassembly. It was time-consuming to have to clean each and every part, usually throwing them into a pan of phosphoric acid to neutralize the old rust and aluminum oxide corrosion that had built up on the alloy parts over the last 50+ years.

I had a spare set of cylinders that were already bored to new .75 over pistons, so those were going in to shorten up the assembly time. The cylinder head came apart easily and the valve seats were just lightly touched up. I was able to reuse the valves once the rust and corrosion were removed. The engine was reassembled using a new screw kit for outside fasteners. I had to drill the heads off of a few of them during disassembly. Once all the parts are cleaned up, reassembly can begin which is fairly straightforward if you have done a few of them in the past.

With the engine work done, the task of wedging it back into the chassis is always a chore, due to the weight and finding the right point underneath to get a little floor jack beneath the cases. Hauling the engine on and off the workbench is getting to be a trying experience for my old bones these days. Fortunately, I didn’t do any serious damage to my body in the installation and the motor bolted up normally.

The rims were really badly rusted, so I put out a call to my friend Rick Bowers in LA and he had a set of OEM DID rims available These were the real deal without the DOT stampings on the side that are the replacements for the original rims. They are probably way too good to put on the bike considering the rust and corrosion beneath all of the paint and in all the little corners of the chassis, but they were available and perhaps the rest of the bike will catch up to the wheel sets sometime in the future.

I spent about 3 hours on each wheel from start to finish. The rear brake cable was rusted to the brake plate which took about 15 minutes to extract without damaging the plate. There was so much corrosion damage from the steel-aluminum interactions on the bike that every fastener needed to be carefully removed and then cleaned to allow easy assembly again. All the alloy parts got the acid bath, then rinse and a coat of paint to help cover up the corrosion damage. The brake plates still had some of the clearcoat paint on them, but it slumped right off when I sprayed them with brake cleaner. The decision at that point is whether to send all the brake parts out for polishing or just scrubbing them up and laying down a coat of cover-up paint, which is what happened in the end.

Once the engine was secured, all the added-on parts followed, including new air filters and tubes. I wound up having to remove the left carburetor again when I went to start it up. The little passage that vents the float bowl was still blocked with leftover varnish and it caused the float bowl to overflow into the air filter tube and filter paper. Once that passage was cleared the bike fired up easily and sounded pretty good after its 45-year-old slumber.

The ignition points were seized on the pivot pins and rusted shut at the contacts. I had 5 sets of left points and no right side ones in stock. I figured out that you can take a left set of points apart, flip the pivoting contact arm over and it fits the opposite side! I was able to dial in the ignition timing, but the results were not totally acceptable. Setting the right side timing wound up with the point backing plate turned all the way retarded and the point gap was probably down towards .012” whereas the left side point gap wound up in the .018” range in order to get both sides to fire at the F/LF marks at idle. Still, it starts quickly and idles down nicely even when cold.

Test ride results: No good deed goes unpunished….

Riding the bike with cutoff shorts and Crocs, I felt something wet hitting my legs on both sides going out on my test run. Returned to find a drip from the clutch cover and the drain bolt. Also, the tach drive housing had a gasket leak. I added a second gasket to the clutch cover, installed a new drain plug gasket and then pulled the bike on the rack for fork seal leaks. It took three hours to get the front end off, the forks removed and apart. I replaced one seal that I had in stock but wound up using a re-chromed fork seal holder that already had a new seal installed. I loosened up the fork bridge enough to remove the left fork ear which had a shipping dent in the side. Using a muffler pipe expander tool, I was able to remove most of the dent. Thankfully, the forks basically slid out of the triple clamps when I loosened the stem pinch bolt. There was a little pool of fork oil above each seal, so they definitely were leaking and the original 57-year-old parts. It wasn’t really unexpected, considering the condition of the bike and the age and storage history, but it added some extra time and parts to get it dialed in correctly.

The transmission shifts wonderfully and the clutch is fairly easy to manage at the lever. I suspect that the speedo-tach will have to go to Foreign Speedo in San Diego for an inspection and lubrication although the needles were pretty steady for the short test runs. The meter bushings lose their lubrication and then they start screaming noisily and the needles start flicking back and forth uncontrolled. Riding with the meters in this condition will cause permanent damage to the meter movements.

More test rides revealed continuing oil leaks on the left side of the engine. I removed the clutch cover again, scraped off the sealant that I used last time, and planed off the cover where a high spot showed up when checked with a straightedge. Again, 2 gaskets were used and this time the clutch cover stayed dry, but then the two adjacent studs with the plain washers and nuts were dripping down the sides. I rounded up two sealing washers and cap nuts and that finally stopped the oil weeping.

The bike fires up with no choke and idles down pretty quickly. These old bikes still ride like ancient pickup trucks when the original suspension parts are kept in place. A good set of rear shocks would help the back end. Just getting the engine installed and running is only the first step to getting a bike fully operational and safe. The parts bill on the bike was close to $2k alone, plus way too many hours for me cleaning and dealing with rust and corrosion on every piece of the bike. I installed a NOS CL72 ignition switch and lock set that came from Holland at a hefty cost. The CL switches have a longer lock cylinder barrel than the CB models, so I rounded up an early CL72 cover latch to help cover up the extended threads on the switch extension. I had to buy a matching OEM key for the steering lock that was still in the bike, then float a lot of penetrating oil into the lock to get it to move. I probably spent twenty minutes just getting the old lock out, finally using a small slide hammer to ease the lock out of the steering stem. There are dozens of little time-consuming tasks like this as you go through the whole bike and test/check all the systems and fasteners that hold it all together. Rebuilding these old bikes requires a LOT of patience and time, in order to have an eventual good outcome.

 In the end, the bike was safe and reliable to ride after 45 years of deep sleep. It isn’t much prettier than when it came to me, apart from the shiny engine and rims/spokes. There is still a lot of rust and corrosion in the nooks and crannies of the chassis and on all of the chromed and polished parts, but it isn’t critical to the “safety of flight” for this vintage Honda. The CP77 is a rare find in the US, so perhaps it will get continuing cleaning and perhaps a new paint job someday to make it look as good as it runs now.

Bill aka "MrHonda" Silver


PS... the bike turned out to have been owned by Steve McQueen and was sold on a BAT auction for $31K!

Monday, July 18, 2022

Burning carbs on the CB550 Honda

Of all the vintage Hondas I have worked on, the carburetor removals on the CB500-550s are about the worst to accomplish in a reasonable amount of time. Of course, on the heels of the CB360T trauma, the owner serves up a 1975 CB550 with 14k miles on it, which is barely running, and wants it sorted out for sale this summer. The bike was faded, dirty, and missing the centerstand. The rear tire was oversized and there was no license plate mounted on the tail light bracket.

The first problem was that the front brake was dragging. I had cleaned out the caliper when I visited the owner’s house, about 25 miles away, a few weeks back. That seemed to have improved the situation, but after getting the bike pushed into my truck for the trip home, getting it back off the truck was a challenge. I loosened the caliper mounting bolts enough to get the brake freed up so I could get it safely off the truck and up into the service rack. Knowing that the caliper was already cleaned up, the issue probably resided in the master cylinder. The little bleed hole appeared to be restricted or mostly plugged up, which causes the brake pressure to remain constant, instead of relaxing when the lever is released.

There was a big scuff mark on the top of the master cylinder cap from a small crash, so it was cost-effective to just order a replacement from and be done with it. Once it was installed and bled the brake function was restored to normal. One down and more to go…

The next big problem was that the ignition key was not a match to the seat lock! The switch had been replaced with an OEM Honda unit with a 21H key number vs. the T2979 lock for the fork and seat. I spent 15 minutes reaching underneath the seat to remove the seat hinge pins, which allows the seat to be loosened up enough to get to the two nuts that hold the seat latch pin loose. The seat can be removed but then you have to take the latch off the frame with the two Phillips screws. One of the screws came out with the impact driver and the other one was in so tight that I had to drill the head off to get it loose.

Removing the carburetors was next and that is never a fun experience judging from my past dealings with 500-550s. The clutch cable dives down between the carburetor bodies on the 550s, as well as a vent tube that also makes its way between carb 3 and 4. Early 500 Fours had a different clutch release system and the cable doesn’t interfere with the carburetors.

The battery was removed and charged, followed by the removal of the rest of the battery box, the air filter housing, then the extraction of the air box behind the carburetors. Honda wrapped the frame around the airbox and there is virtually no room for the carbs to come off of the manifolds to pull them off the bike. After a lot of wrestling and pulling, I was able to remove the carbs from between the head and the airbox. Usually, you can figure out how to disassemble these things, but on the installation, I discovered that removing the clutch cable mount at the back of the engine gives much-needed room to maneuver the air box in and out of the bike. Still having to disassemble half of the bike to get the carbs on and off is not a fun way to spend your time.

Once off, the carbs were in relatively good condition inside, but I replaced the internals with kit parts and replaced the intake manifolds with a fresh set. The biggest problem with the carburetors was that the welsh plugs located at the outsides of the 1 and 4 carburetors were missing! These are not separately available parts from Honda and online searches for a 1/2” (13mm) plug came up dry for the most part. Apparently, there were plugs like that for some lawn equipment carburetors that might work, but most listings didn’t show sizes. I had a full set of used carburetors that wound up being parts donors just for those two little plugs.

I discovered new electronic ignition systems on eBay, obviously from China, as they were $69 vs. the $150+ Dyna kits. I ordered up a kit, which came quickly, but without any instructions which could be a problem for novices. Fishing the old point plate leads out from the little clamps under the engine and then up next to the air box takes a bit of time and patience but it is mostly plugged and play. I put the rotor trigger on backward which lead to a no-start condition until I switched it back 180 degrees.

I had already adjusted the valves and camchain, replaced the spark plugs, and wound up putting on new replacement coils, as the old wires were hardened and had been shortened before to keep good connections.

So, initially, it fired up sounding decent, but the idle was erratic. I was feeding it with a remote fuel bottle so I could make adjustments to the carburetors for synchronization. The engine compression readings were 180, 150, 145, and 170 psi, so you can’t expect really even readings with variable compression issues within the engine.

I had cleaned out the petcock screen and disassembled the petcock to check for any issues, which were not a problem. Adding fresh fuel to the tank, I reassembled the tank and seat, then took it out for a short run around the block. I set out for a longer run, which went okay until I was a mile away then it died. I had only put about 1.5 gallons of gas in it, so switched to Reserve and it started back up again. On the return, it ran well up through the revs, but at the top of the hill, it started to falter again. I kept the revs up enough to get it back to the garage, but it sounded like it was only running on 2 cylinders, plus it started peeing oil off the left side of the engine beneath the countershaft cover.

These engines seem to suffer from flattened o-rings that create oil leaks into the little chamber of the countershaft cover. Other common oil leaks come from defective oil pressure switches and there is also a very large diameter o-ring that surrounds the oil pump where it bolts to the body. After replacing the o-rings on the pump, and test riding it again, the oil drops kept dripping when the bike was on the side-stand. That usually only means one thing… the shift shaft seal is leaking. So, off the cover comes again (the first time required drilling out one of the screws) and confirming the leak at the seal. I don’t usually stock parts for 500-550s, so it was back to eBay for a $10 seal and to wait some more. It took 4 days for a small seal to come from 100 miles away and the part number on it wasn’t a match for what was listed on the auction page or parts lists, but apparently, Honda superseded the part number and the older seal is the same dimension as the upgraded one. One more problem solved.

In the meantime, I noticed a little gasoline drip from the petcock lever, so drained out 4 gallons of gas that I had just put in and removed the tank to check the petcock parts again. There is only one little o-ring that can cause a leak on this style petcock, so I thought that this might be the cause of the leak.

I noticed that there was a special flat washer on the edge of the workbench that seemed familiar, so when the petcock came apart again, I discovered that it had been left off of the reassembly last time. More senior moments…

BUT, as I was draining the gas tank for the petcock check I lifted the gas cap and heard a little swooshing sound as if there was a vacuum being created by the exiting fuel flow. I had just put a new aftermarket gas cap on the tank after seeing the disaster cap on the CB360 that was here previously. What I noticed was that the little v-shaped vent hole on the cap showed some kind of white material that seemed to be blocking the hole. The cap pieces are held together with a small screw, so I unscrewed the cap assembly and found a tiny piece of what looked like cotton that was sitting over the vent hole. I can’t determine if all of these caps are made the same with little cotton balls inside, perhaps to soak up any gasoline splash inside the tank, but I wasn’t leaving it in there. A good 15-minute test run revealed no fueling problems as had happened before. All the header pipes were at the same temperature using the laser temp meter, so removing the cotton ball seems to have resolved the stumbling and stalling condition.

With the petcock reworked and the fuel tank installed, I filled the tank back up again. Rode the bike again with good results overall. I aired the tires up to specs and thought the end was in sight, but then checked the date codes, which ended in 00 and 02, so new tires, tubes, and rim bands were ordered.

While checking the electrical system out, I discovered that this was one of the bikes that Honda had put the infamous beeper on the turn signal system. The signals wouldn’t flash at idle and the beeper made a horrible sound, so it was disconnected. The flasher unit, which was an original Signal Stat 142 unit, which apparently is no longer in production. These are the tiny rectangular flashers the size of two sugar cubes with a little rubber mount that clips the unit to a bracket on the electrical panel. Fortunately, the people at offers an aftermarket unit for about $12, so that went on the order list. The flasher came in promptly and the turn signals are working fine now.

I initially checked around for a centerstand and the mounting hardware, but nothing came up and I got no responses from the Facebook forums that I am subscribed to for vintage Honda bikes and parts. I fed the part number and description to the owner, who miraculously found one that was incorrectly identified on eBay as a Super Sport part (different than the K models). It was purchased and shipped to me for installation. This became another time-consuming and frustrating repair process as one of the exhaust pipes had to be removed to access the frame mounting points in order to push the pivot shaft into the frame mounts and the stand tubing.

The stand was fitted up okay, but then the challenge to try to reconnect the return spring reared its ugly head. With the exhaust pipes in the way on the right side, the access to the end of the spring and the hook on the stand was restricted. I tried all kinds of tricks to try to get the spring connected and even went to the auto parts store and bought a brake spring tool, which was cheaply made in China and didn’t really work in this kind of application even when some extended tubing was used to gain more leverage on the spring end. Finally, I found a thick 5/8” lock washer and used it to bridge the gap successfully. Not pretty or factory approved, but it works perfectly fine, but I spent more than a half hour of my time, wrestling the parts back in place. It’s so much easier to change the rear tire when you have a centerstand to prop up the bike!

The left side dyno cover badge was scrubbed off on a right side tip-over and the replacement parts are in the $100 range, plus the three little clips that are $6-10 each (3 required), so I thought I better check with the owner before putting that shiny piece on an otherwise dull-looking daily driver bike. The reply was a thumbs down on that question.

The bike did get an oil and filter change on top of everything else, so at some point, it will be sent back home with a full service and hopefully regular use at the beach this summer. With fresh rubber and a brake upgrade, it can resume being actively ridden again after probably a 15-year sleep.


  Bill Silver aka MrHonda