This portion was written before the actual engine teardown session: Read further for actual results…
The video teardown for the engine was setup for a Friday by local motorcycle enthusiast, named David, who recently acquired a CA77 Dream, himself, to add to his growing and eclectic collection. David is a local educator for a charter school and lends his enthusiasm and knowledge to some of his students, as they learn the arcane world of motorcycle engines and systems, all of which were built before their parents were born, in most cases.
Starting with an intact engine on the workbench, we planned to film the gradual teardown, bolt-by-bolt, screw-by-screw and piece-by-piece, until it was just a large pile of aluminum and steel. Hopefully, the final edit will be comprehensive and compelling for new owners to take a shot at rebuilding their own engines, if they follow along with the steps on the video. The first stage, obviously, is the overview and then teardown, analyzing the components as they are removed. With a low-miles engine, most of the internal parts should be in a lightly worn state, however when oil has been sitting in a crankcase for 30 years, the additives in the oil will fall out of suspension and everything goes to the bottom of the crankcases. Generally, this is where you find a thick, gooey mess of sludge, dirt, contaminates and debris.
I would expect that the oil filter has never been serviced in this engine, as the clutch cover screws are undisturbed. If the outer oil filter cover isn’t of the “big-hole” design, it is impossible to remove the oil filter assembly from the engine without removing the clutch cover itself. The centrifugal oil filters are highly effective at separating dirt, particles and debris from the oil stream as it is pushed through the spinning filter housing. The early Honda Dream owner’s manuals show the filter cleaning process, but they don’t explain how to get the pressed –on cover off the housing when there is no facility for doing so.
With the engine in non-operational status for 30+ years, the continuous clutch spring pressure upon the clutch plate pack will have squeezed all the lubrication out between the plates, then the fiber and steel plate sets basically bond themselves together in the condition known as “stuck clutch,” when the clutch lever becomes very hard to pull in and putting the shift lever into a gear yields a grinding sound, followed by stalling of the engine and/or a jerky, sudden uncontrolled take-off. Sometimes the clutches are “lightly stuck” and running the bike around in a safe place with the clutch lever pulled in, while the bike is in 1st gear will cause the plates to release and break free from each other. While this seems like a great time-saver, the steel plates will have a layer of fiber material stuck to the surfaces and this roughness will create clutch drag as well as causing small particles of clutch fiber plate and rust to be thrown into the engine oil supply.
Now, for the actual teardown results and associated problems:
Note: David setup 2 cameras and did a quick test to check them for functionality and lighting before we began in earnest. Sadly, at the end of about 4 hours of filming, it was discovered that we had lost playback capabilities, so apparently the 4+GB of video content was lost forever.
The actual teardown went along fairly smoothly. The oil had been drained out a few days prior and wasn’t looking very good as it was transferred to the oil waste can. Pulling the tappet covers off showed signs of varnish and old oil residues present. When the cylinder head top cover was removed, the cams and rocker arms were still bright and shiny, but there was a lot of varnish on the non-moving parts inside. The camshaft sprocket locking nut was loosened along with the thru-bolt in order to be able to separate the cams from the sprocket assembly. The camchain was parted at the master link, followed by the cylinder head removal up and off of the studs. The tops of the piston crowns had a light coating of soft carbon and the combustion chambers and valve heads were all lightly carboned up, as well. Pulling the cylinders up off the pistons revealed some stains on the cylinder walls, but no appreciable wear or damage. The piston rings were still free in the ring lands of the pistons and the piston pins came out with very little prodding.
The central camchain guide roller was slightly deformed from steady camchain tension for many years, as was the camchain tensioner roller. Again most of the inside surfaces of the engine castings were coated with brown-ish varnish and oil deposits.
The next step was to remove the right side components, including the stator, starter motor and chain. The rotor bolt was somewhat difficult to remove, but once it was off the starter clutch rollers and springs all looked pretty fresh. Next the engine was turned on the right side, to allow for removal of the clutch cover to access the clutch, primary chain, shift selector parts and the oil filter.
The clutch plates were lightly “stuck” together, but pulled apart with finger pressure. The fiber plates had little wear and the steel plates were still flat and showed little fiber plate transfer on the surfaces. The primary chain tensioner was removed and then the whole front sprocket/chain/clutch outer was removed as a unit. More varnish and gooey oil oozed out of the cases many recesses that trap oil normally. Once the left side components were removed, then the engine was flipped over to access the oil pump/filter. As the oil pump was removed a thick layer of mucky oil was seen nearly blocking the oil screen all the way around. One would get the feeling that the bike was driven hard for those first thousand miles and then parked unceremoniously without ever having the benefit of an oil change or service.
The engine cases were parted and the lower engine crankcase showed more layers of grease and grime that had settled down to the bottom of the engine over the years. The crankshaft looked fine, other than the oil film coating the surfaces. The transmission was shifted through the gears slowly, as we watched for the amount of gear dog engagement in the 2nd and 3rd gear shift positions. Gear dog overlap was somewhere in the 30-40% range, a good bit short of what is desired, so a couple of pairs of offset cotters will be installed to shim up the gears and consequently the engagement overlap of those gearsets.
Very little wear was seen on the kickstarter shaft, where the bearings ride and the low gear bushing still had its little ridge in place, indicating that this truly was a very low miles engine assembly. All of the affected engine parts are being sent out for steam cleaning at a local automotive/transmission repair shop. This process removes the varnish and petroleum deposits from just about everything, but tends to leave parts subject to flash rust and leftover scaling of the raw aluminum.
The final part inspected was the oil filter and true to form, it was already packed with about 1/8” of thick, hard deposits of dirt, metallic filings and other contaminants. David was shocked to see how much crud had collected in the filter after only 1,000 miles, so he’s keen to open his bike up soon for service work and filter cleaning, as well.
David has access to some more high-end video gear for his return when we do the “engine assembly” video portion of this engine. Depending upon what we find in his personal CA77 Dream, it may be the subject of the next “disassembly video” attempt.
Apart from a damaged shift shaft spline section, almost all of the original engine parts will be reused. The cylinders will be sent out for honing and we’ll probably re-ring it if the end gaps are excessive on the original ring set. Some of the engine components are getting quite scarce and it was a happy discovery to find that CMSNL in Holland had just released some reproduction camchain guide rollers, made to factory specifications, so one of those will be installed in this virgin CA77 engine soon.
It was fun to have someone watching and asking questions about the engine teardown, as this usually is a silent, one-man process for me, which takes several hours to complete. Cleaning of the parts, scraping the asbestos gaskets off the cylinder base and engine crankcases are tedious time-wasters, as far as I am concerned, however it MUST be done and done well so there are no leaks in this engine for the future.
Bill “MrHonda” Silver