Sunday, December 13, 2020

The Classic Honda used bike minefield… CB/CP77

The line from Forrest Gump that goes, “My mom always said life was like a box of chocolates. You never know what you're gonna get.” certainly applies to prospective purchases of vintage Honda motorcycles.

Unless you are buying from the original owner who has all the service records and a list of mods or damage repairs, you can never really be sure about just what you will find when you set your eyes on that rare bike that you have been lusting for during the last few years.

Case in point: I was helping a friend try to track down a black Honda CB77 Super Hawk to match is original black CB160. I had recently helped him market his CB450 Black Bomber so now he was hunting a black Super Hawk. I had sold a couple of really nice bikes in the past two years, but it seemed like very little was out for sale in the past few months. Hoping to avoid a blind purchase of some bike that was far, far away, an “opportunity” passed though my searches that appeared to be the black CB77 that my friend was seeking right here in San Diego County.

In the photos, it certainly appeared to be a “flat bar” CB77 of about 1964-65-ish vintage, but it was listed as a 1965 CP77 instead. The production CP77 (non-Police bike) models were never sold in the US, but they seemed to have been offered in Canada back then and a few of them migrated down to the US over the years. The model causes confusion as it might be considered the “street bike” version of the CP77 (actually CYP77) Police model. Again, a few Police models did go to Canada, but never to the US. The non-Police models look like standard CB77 Super Hawks, except that they have very high handlebars, turn signals, a sidestand, solid footpegs and the tail light that was only seen on the 1961 CB72-77s in the US.

Looking at the photos of this bike, it was obvious that the handlebars had been changed, the original turn signal switch was missing as were the rest of the winker parts. The side stand was not present and the tail light appeared to be the generic CB72 taillight used on 1963-66 models. So, in essence, the bike was reconfigured from the original CP77 roots to an early-style CB77 look.

Some of the current owner’s history was shared in that he had reworked the front forks due to some accident damage, had given it a good tune-up and may have replaced the tires. Unfortunately, the tire choices were 3.25x18 front and 3.50x18 rear which will ALWAYS upset the bike’s ability to stay steady on the centerstand.

I was requested to check the bike over prior to the sale transaction, which took me 50 miles from home. The bike presented itself as an unrestored model, which had a few dings and chrome pitting, but seemed overall a solid base to work from for someone who was willing to spend some time and money to get it back towards original condition again.

I started the engine, which sounded healty and firing on both sides evenly. In retrospect, I should have taken it out for a quick spin to check it for clutch slippage and/or clutch release issues.

After some wrangling, the owner and buyer made a deal and we loaded the bike into the back of my Tacoma for drop-off in Solana Beach, CA. By the time I returned home there was a message about what to do with the bike to get it serviceable and closer to stock CB77 shape. Obviously, the tires were top on the list and replacement rubber in the stock 2.75x18 and 3.00x18 sizes were ordered up.

The next question came up about how the steering lock works. At first the key was sticky and the lock wouldn’t move properly. With a few squirts of graphite lube, the steering lock was working fine, but the place where it was supposed to lock into was not present. A close-up photo revealed that the whole steering lock portion of the frame was cut/sheared off, perhaps in an accident. I can’t say that I have ever seen this happen before on a Super Hawk, as the steering stops for the stem contact the frame down behind the steering lock bridge portion. It was a mystery and a problem not easily remedied.

After a batch of parts had arrived, I arranged to swing by the owner’s home and dig into the project, starting with changing out the tires. The tires dates were back in the early 2000s and their oversizes caused extra difficulty in removing them from the rims. I started with the rear tire and once it was removed, there was a good bit of rust corrosion in the rim bead area and around the spoke holes. I knocked off the worst of it and wire-brushed the loose bits. I wrestled the new tire back on and prepared to install the wheel again, but saw signs that the ends of the cotter pins on the rear sprocket castle nuts were hitting something. There were signs that the cotter pin ends had been hitting the inside of the chain guard bracket, which also showed signs of being rewelded previously.

An even closer look revealed that the rear shock bolts had been installed backwards so the thick outer nuts were very close to the sprocket nuts. The shocks required removal and a 180 degree turn on the bottom to get the threaded portion of the lower clevis set properly, so the shock bolts, which have thin heads, were installed with them pointing outwards. The previous owner had commented that he had to put a longer chain on the bike to allow the rear wheel to be moved further back enough to clear interference with the forward edge of the rear fender, next to the swing arm. That sort of made sense, but then I discovered that the rear sprocket was stamped 32 instead of the stock 30 tooth markings. The stock 94 link chain had been included with the bike’s spare parts, but obviously wouldn’t work with the big tire combo.

I had brought a spare pair of new aftermarket chain adjusters to help brighten up the rear axle area, but one of then turned out to have stripped threads for the adjuster bolt. It is amazing how much time is spent sorting out all the little issues like these when you are wrenching on an older Honda bike with a little known history.

Once the rear wheel was reinstalled, it was time to move onto the front tire replacement. The first thing to notice was that the pinch bolt for the left front axle case was an Allen bolt, instead of the normal bolt with a 14mm head. Secondly, the bolt was loose in the threads. The bike had to be jacked up in front off of the starter motor, but the bike was also supported by a 2x4” board beneath the center stand feet to give the bike enough room to pull the over-sized front tire out of the forks and front fender. I had to remove one of the fender stay bolts to allow the wheel to clear the the fender’s cable stays. Apart from pinching the inner tube (there was a spare, thankfully), the front wheel went back together okay, except for installing a few front brake cable. The cable adjusters were mostly used up in getting the brake to adjust properly, which turned out not to be worn out brake shoes but the brake linkage arms had been installed one spline off from where the punch marks were shown. The wheels will be coming off again in the near future so the fenders can be removed and repainted, so the brake cam/arm issues can be addressed then.

The last few jobs for my 4-hour stint included an oil change, change the spark plugs and check the ignition timing. The first two tasks were easy enough but the last one brought a shock to me when the dyno cover was removed…

Instead of the typical CB72(L) rotor marks on the face of the rotor, I was faced with C72 marks which can only come with the use of a Dream or Type 2 engine CBCL engine. Beyond the surprise of seeing the wrong rotor installed, instead of a central rotor bolt to attach the rotor to the crankshaft there were two nuts, double-nutted on a stud! I have NEVER seen this adaptation done to a CB77 engine before or any other one, which leaves one to wonder, whether the end of the crankshaft threads were damaged previously and this was some kind of creative repair to keep the bike on the road.

The rotor had some black marker hash marks 180 degrees from the only stamped T and F marks on the rotor, which appeared to be properly set. I hooked up a dynamic timing light to the ignition and verifed the right side marks first. Then I used the black line mark as a hopefully accurate mark to set the left side ignition timing. The marks showed that the timing was retarded a few degrees, so a small adjustment was made to correct the error. The engine idles evenly and sounds like it has good compression. There are no signs of smoking, but there is no known history of what has been done to the engine beyond what has been discovered.

A quick ride around the neighborhood revealed that the transmission didn’t want to shift back into neutral when the bike was at a stop in gear. This is almost always due to someone removing the thin wire retainer rings from the clutch hub. The retainer wires help hold the first few clutch plates on the hub, which helps the rest of the clutch pack separate and release it’s grip on the transmission shafts. When the engine torque is removed from the transmission shafts, the shift selector can do its job of selecting whatever gear you wish, including neutral.

So, the next few upcoming hours will include removing the clutch cover, inspecting and cleaning the oil filter, checking what appear to be excessively strong clutch springs, looking for missing retainer springs and then popping in a new shift shaft seal while the cover is off.

If that doesn’t reduce the amount of clutch lever force currently experienced, then the kickstarter cover will be removed and a new clutch adjuster will be installed to reduce the amount of thread slack between the adjuster and clutch lifter arm threads. Reducing the slack translates into increasing the amount of clutch pushrod travel which separates the clutch pack more completely.

$100 worth of gaskets, seals, chain adjusters, clutch springs and a clutch adjuster have been lined up for the next round of repairs, hopefully the last for awhile.

Round Two….

The priority task was to address the clutch release issues, so the right side exhaust was removed to allow the kickstarter cover to be taken off to inspect the clutch adjuster threads/slack. Pulling and pushing the clutch lifter arm in and out of the clutch adjuster showed excessive slack/play between the two parts. The clutch adjusters are made of aluminum so the coarse threads are eventually worn down from repeated cycling of the clutch while riding. This bike was showing 10k miles and the parts looked original, so a fresh clutch adjuster was installed.

An unfortunate surprise when the kickstarter cover was pulled back was a splash of motor oil that had pooled below the crankshaft/starter clutch. Using a flashlight to check for oil trails, didn’t show anything that was really active on seals that were installed in the cases. So, that left the little seal that installs in the center of the starter clutch hub as the probable cause. Ordinarily, I would pull the rotor bolt and use the 16mm special tool to remove the rotor to check the starter clutch roller springs and the condition of the oil seal on the starter clutch hub. In this case, the C72 rotor that was looking back was being held in place by a stud and nut/washer instead of the normal rotor bolt/washer. As this was a house call visit, I didn’t have all the tools I needed to go further in this direction, so I had to wipe up the oil mess and leave it alone for the moment.

The new clutch adjuster was greased and installed, then the kickstarter cover reattached. Pulling the clutch lever felt about the same as before. So, the next step was to go to the left side, remove the exhaust system and footpeg/linkage to allow the clutch cover to be removed. The cover screws all came out easily and the cover came off with the gasket intact for a change. Pulling the clutch spring bolts out revealed what appeared to be the “white springs” which are stock for 305s of that time-frame. That was puzzling, but pulling the the plates off and looking carefully showed the probable cause of the clutch drag problems. I was somewhat surprised to see that the oft-removed steel retainer wires, which hold the first few plates in place, were still in place.

While the friction plates looked normal for used parts, the steel plates showed all the signs of an earlier “stuck clutch” condition where the plates had been pressed together for many years of storage, then adhered together transferring some of the friction material to the steel plates. It generally looks like a combination of rust and friction material that is left behind when the clutch is jarred loose by running the engine with the clutch lever pulled in until the clutch plates get unstuck.

When this approach is used, the leftover material on the steel plates keeps dragging against the adjacent plates which prevents a clean release of the clutch pack and causes difficulty in finding neutral when the bike is in gear and stopped at a light or stop sign. I had brought a set of steel plates that were NOS and rather than try to clean the old ones, we popped in the new set, reassembled the clutch plates and springs and then checked the clutch release function. You can watch the clutch separate by pulling the clutch lever in and kicking the engine over. When the clutch releases, you can see and feel the disconnect between the engine and transmission. It appeared to be working correctly, so we put it all back together again, refilled the crankcase and fired the engine back up again. Even driving the bike just a few yards in gear, then selecting neutral yielded the little red neutral light lighting up with ease.

So, the clutch release issues were finally solved and the bike is now driveable in traffic without struggling to get the transmission into neutral with relative ease. The total labor time ran close to 3 hours in wrangling all of the parts for the clutch release problem. That’s good news for now, but that oil leak is still present and will need to be addressed sooner than later. The owner wants to remedy the loose fork covers by replacing the little rubber ring packings that sit down inside the fork rings. That requires removal of the front wheel, fender, handlebars, fork bridge and all the related parts. So, that is the next round of labor to hopefully complete the major repairs and complaints for this 55 year-old classic Honda Super Hawk.

Round Three

This time, we had to resolve the mystery of the C72 rotor mounted on the end of the crankshaft with what appeared to be a stud instead of the conventional rotor bolt/washer that screws into the end of the crankshaft. I sourced a new CB72 rotor from my dwindling parts supplies, loaded it with new springs, caps and rollers ready to install, along with a seal kit to remedy the previously discovered oil leak issues. I brought a 3 jaw puller to attempt the rotor extraction and once it was in place, a few hard turns of the tool’s shaft brought satisfaction as the rotor flew off the end of the crankshaft, scattering little starter clutch springs, caps and rollers around the floor. With the rotor removed, you could see that the oil seal for the starter clutch hub was half-way falling out, which accounted for the oil leak. The main crankshaft seal seemed to be holding up okay, so we just replaced the clutch hub seal with a new one and reassembled everything with the new rotor. The mystery of the end of the crankshaft was resolved when it was revealed that a bolt had been welded into the end of the crankshaft! I guess no one will ever know why the previous owner took that path of repairs, but the end of the crankshaft still runs true, so it is what it is and it is good enough for the future.


Bill “MrHonda” Silver



  1. I have seen kick starters and shifters welded home, but never the nose of the crank. Some discoveries are stunning. The little top hat on the kick starter is almost always boogered, but luckily these bikes have a robust electric start. Lotsa chuckles

  2. A bolt welded on the end of the crankshaft. Bill, you find the weirdest fixes! The ones that not supposed to be found. Enjoyed the story. And Merry Christmas.

  3. A bolt welded on the end of the crankshaft. Bill, you find the weirdest fixes! The ones that not supposed to be found. Enjoyed the story. And Merry Christmas.

  4. A bolt welded on the end of the crankshaft. Bill, you find the weirdest fixes! The ones that not supposed to be found. Enjoyed the story. And Merry Christmas.