Tuesday, August 29, 2023

Rescuing a CL77 restoration… RTV is not your friend.

For some reason, the last four vintage Honda repair bikes have come from the Santa Clarita area, which is about 165 miles away. First, it was a blue CB77 with a seriously stuck engine, then a pair of bikes from the same owner: CB77 and CB550 for engine work. Now, through a relay of connections in the community, a newly acquired CL77 came down from the owner with a broken kickstarter system. The referral came from a shop in the SFO Valley, who called my friend Ed Moore in TX who called me because I was a whole lot closer to attending to the problem.

There was desperation in the owner’s voice as he had just purchased what seemed to have been a “restored” red/silver CL77 from the 1967 vintage. It had been a dream of his to own one since high school and now that he had purchased this shiny red/silver Scrambler, the dream had turned into a nightmare.

When he brought the bike to me, it appeared to have had a lot of cosmetic work done, but after a couple of starts, the kickstarter arm fell backwards and had become disconnected from the rest of the engine. Often this is a problem with either the kickstarter knuckle cracking and splitting open, so that it jumps over the splines on the kickstarter shaft, or sometimes the shaft will shear off.

With the kickstarter cover removed, the kickstarter shaft was still intact and the knuckle was not damaged. The apparent problem was that the kickstarter shaft was not engaging with the low gear via the spring-loaded kickstarter pawl. Nothing to do at that point, except extract the engine assembly and split the cases for a look. And so it began…

After draining some dirty oil contaminated with flecks of silver aluminum, the engine was pulled and hauled up onto the workbench. At about 100 lbs, lifting these things up and down from the workbench gets to be a mighty chore for my 75-year-old body. I rolled it back to remove the oil pump which allows the engine to sit flatter on the bench. Then, the clutch cover was removed to access the clutch and shifter selector parts. I could see that the engine cases had been reassembled with some kind of white RTV sealant, while the outer oil filter cover was covered in black RTV where the o-rings normally do the job. When the filter cover was extracted the shaft was jammed inside the cover because the previous mechanic hadn’t indexed the locating pin properly inside the recess made for the job.

My notes for the repair invoice included:

*Bike has extensive restoration work, but kickstarter does not engage the engine.

*Remove engine assembly and split engine cases for inspection/repairs.

*A blob of black RTV above the crankshaft indicates a misplaced crankshaft locating pin incident.

*Lower right rear engine mount bolt missing, left side finger tight.

*Engine had been opened up previously and some kind of white sealant RTV used to seal the cases.

*Kickstarter diagnosis: Kickstarter pawl retainer stop on kickstarter shaft was sheared off, allowing the pawl, pin and spring to escape their respective locations. Requires replacement of the shaft, pawl, cap, spring. Second gear had been previously replaced with one from an earlier model that has non-matching gear dogs. Replaced. 2nd M/S gear with correct type and installed offset cotter set to increase gear dog engagement. The low gear bushing is worn with the center ridge detached from the bushing body. Replaced with NOS part.

*The oil filter shaft and body were seized from improper installation. Replaced with good used, clean parts and reinstalled. Clean all remnants of RTV from engine cases and oil filter outer cover, clean oil residues from the bottom case half. Remove glued-on intake manifold insulators and install new o-rings.

Broken ear that retains the kickstarter pawl

Comparison of a broken one on the bottom and a good one on the top.

When replacing all the damaged kickstarter parts, I noted that the engine case showed a previous attempt at putting the cases together with the alternator side locating pin not indexing with the hole in the bearing. When the bearing isn’t rotated correctly, the pin gets shoved into the engine case, usually breaking out a chunk of the casting, plus the oil feed hole doesn’t match up. Honda went to a larger pin later on to prevent these kinds of mishaps, but I have seen more than a few of these engines damaged by the pin/bearing mismatch. With the cases apart, I checked to see if the bearing and pin had been realigned after the damage had occurred and the bearing alignment marks were correct. So, someone made the mistake of relocating the bearing and then back-filled the damage in the case with RTV. Because these engines don’t have a lot of oil pressure, these repaired mishaps don’t usually cause problems with oil leaks in the future.

I had a replacement kickstarter shaft along with the low gear bushing, pawl, spring and cap for the ratchet function. I noticed that there was not enough gear dog engagement for 2nd gear, then discovered that the gear had been changed with one from an earlier version. Later gears have back-cut gear dogs that pull each other together during gear engagement, but the early ones had straight dogs that often bounce off of each other, especially when there is insufficient engagement.

I installed a pair of offset cotters, of which I have only a few left, in order to increase the engagement, after installing the correct 2nd gear. The cotters are stamped and probably forged steel, then machined, but they are not plug-and-play, requiring some modification of the edges and ends to facilitate them sliding smoothly in the shaft track. Once everything was reassembled, the gears all stayed where they belonged and the engagement of the gear dogs was now within specs.

When the owner dropped off the bike, he mentioned that the right side carburetor slide was sticking, so his remedy was to file/sand down the chrome off the slide until it quit sticking! That’s not the path of repair that I would have chosen, but some carb body cleaning and knocking down the high spots should clear the interference problem when matched up with a replacement slide. When I examined the slide, it was obviously a left-side slide, so perhaps they were switched previously which would explain some high idle and other running issues.

I noted that there was evidence of severe varnish coatings in both intake ports, looking like they were coated with Permatex, but it was from years of sitting with old fuel solids coating the ports instead. So, that begs the question: Do I tear down the top end and clean the head/valves and piston crowns or do I start it back up again as-is, because it had been running previously?

I removed the tappet covers and inspected the valve clearances, which were all in spec. Nothing looked suspicious, but you can’t really see the condition of the cams and rocker arms without pulling the top cover off, which I noted looked like more RTV, but in fact, was axle grease! I opted to pull the top cylinder head cover off and have a look at the top-end components, plus verify that the breather plate drain holes were positioned properly. Happily, the covers came off cleanly and the condition of the cams, rockers, cam sprocket and camchain were all fresh-looking and functional.

Saturday was the engine installation day, so I gingerly eased the 100 lbs of steel and aluminum down onto my rolling cart and off we went to the awaiting chassis. I wrapped the frame tubes with rags and a towel to prevent damage to the paint as the engine was wedged back inside the frame. I use a small trolley jack to get beneath the engine to help position it for mounting bolt installations. The long bolt and spacers that go through the frame and oil pump need to be aligned just right for easy installation.

Once the engine bolts are secured, the rest of the dance includes hooking up the electrics, setting ignition timing and tacking on the tool box, air filter brackets and filters/tubes and carburetors.

Speaking of the carburetors, they were cleaned in my ultrasound machine, then the troublesome left side body was checked and the high spots removed. I had recently received a batch of used slides, including some of the later model alloy slides which seem to give a little looser fit in the carburetors. There were signs of a Keyster carb kit installation, but the original needles were still in place. The biggest issue was that the float levels had been set at 26mm instead of 22.5mm which obviously has a big bearing on engine function and performance.

I hooked up a fuel bottle and fired the engine up on the first kick! I let it run for a few minutes to check for oil leaks and any other problems, but it purred along nicely. I followed up with the air cleaners, side covers and finally the exhaust pipes. The exhaust was from a 1966 bike with the slip-on muffler, despite the 43k 1967-series serial number.

The kickstarter cover ear was broken off at the shop when they were trying to remove the cover to inspect the kickstarter issue in the beginning. This is where the inner cover is located, so there is no support for banging on the screws with an impact driver or chisel. Fortunately, I had picked up several CL engines, and several had kickstarter covers attached, so a replacement was readily available.

Towards the end, the owner mentioned replacing the headlight bulb due to a failed filament, so some electrical work was tacked onto the final repairs. The headlight bulb and rim were not grounding to the shell or speedometer as the pigtail was missing from the speedometer base. There was a mixup with the green and green/white wires, which normally creates a blown fuse situation. I wound up running a separate ground wire down to the steering damper 6mm mounting bolt to achieve the necessary ground path for the lights. The neutral and instrument lights were all blown out, so I suspect that someone had tried to run the bike with a low/dead battery and the generator went to full output and blew out the bulbs.

The bike chassis parts were eventually all re-installed and the bike was given a test run. All systems were a go with clean transmission shifts, easy starting, and all electrical systems functioning as designed. I called the owner to tell him that the bike was ready for pickup. It was just a week after he dropped it off and he was very excited to finally drive his dream bike Scrambler and enjoy it as it was originally designed by Honda.

Restoration work is fine if you are aware of the various issues that arise when you repaint and rebuild the bike from top to bottom. The chassis work was done pretty well, but the engine work left a lot to be desired and eventually remedied by MrHonda. It was fun to ride a Scrambler that had good brakes and the muffled exhaust system still had a bit of a ring to the exhaust note as it shifted through the gears and roared down the road.

It’s always a good thing when you are able to put one of these bikes back into full function to be enjoyed and admired by strangers who may have never seen/heard one before, but still recognize it as a classic machine.

Bill Silver aka MrHonda


1 comment:

  1. Glad to hear of another Honda 250/305 on the road. A few years ago I had purchased a CB77 that had been "restored". The cosmetics were nice but the engine was a nightmare. The timing advance mechanism in the cam sprocket was seized up and wouldn't rotate. I never opened it up and sold it off to someone who just wanted to static display it. Then I bought a good condition runner that unfortunately had a tired engine. I rebuilt that engine myself using your book so that I wouldn't screw things up and it runs a dream! I think original bikes are best because you just never know who is doing the work. I'll take nice condition original bikes that were assembled by Honda and not some random butcher in his garage looking for a quick flip.