The problem with most eBay purchases is that you really don’t have a good idea of what you are buying until you get it delivered home. Several such owners have sought me out to help them troubleshoot and solve some vexing problems related to bikes which have had either long-term storage or repairs/restoration work which was sub-par in some respects. They may look pretty desirable and sound like a sure bet when you read the descriptions, but often the sellers of these bikes are not knowledgeable about their product and it is left to the new owner to sort out unimaginable problems of various magnitudes.
Another friend of a friend recently purchased a 1965 CA77 Dream which was repainted (looks like rattle can to me) with a possibly rebuilt engine at some time in its recent past. The bike was non-running when received, an incorrect battery installed, the carburetor rebuilt with a “Keyster” kit (more on that later) and was missing the air filter tube that goes between the filter (looks original) and the carburetor.
Ah, where to start on a bike like this? Well, the first task was to connect the battery, which was too small and had reversed terminal polarities. The original ground strap was too short and the end was damaged anyway. Some braided wire was included with the bike, so with a modified eye-end for the motor mount bolt, a secured ground was established. The tool tray/battery hold-down was missing and wouldn’t have helped because the battery was too small.
The carburetor was pulled back off as the carb kit that was in a parts package showed that it was incorrectly jetted from the manufacturer. They have been advised on several occasions that the correct jetting for a CA77/78 model Dream is #35/#120. For reasons unknown, the makers have been providing #40/#130 jetting which will fuel-foul the standard plugs in less than 5 minutes. It took calls to Western Hills Honda for OEM pilot jets and a Honda dealer in Oregon to supply some correct main jets. Early Honda bikes had JIS thread pitch parts, which are identified with a thin ring that is machined into the outer edge of the jets. ISO threaded pitch jets are blank on the outside and don’t fit the jet holder or carb body. The float level was reset to 26.5mm and the air bleed holes in the carb throat were blown clear with carb cleaner. Normally, this standard jet set-up works fine in 305cc Dreams, but this one continued to run rich at idle, requiring the air mixture screws to be backed out about 2+ turns, instead of just one and a quarter.
The fuel mixture issues are compounded by the ignition system for various reasons. Unfortunately, the ignition points were replaced by the Daiichi aftermarket brands which are totally unacceptable for installation. The points require full retardation of the point plate and a reduced point gap down to about .010” just to get it to time correctly at the F mark on the rotor. The only fix would be to open up the adjustment slots on the backing plate, so the point gap could be increased back into the .012-.016” range. On top of this issue, the spark advancer, which is part of the camshaft sprocket, tends to have weak springs which allow the advancer weights to swing out prematurely, so that the engine is idling with 20+ degrees of spark timing instead of just five. The advanced spark changes the vacuum signal to the metering circuits on the carburetor, which draws in excess fuel at idle speeds.
After reworking the plate and retarding the timing a few degrees the bike fired up and ran pretty well. What was a larger concern was that the breather tube was drooling oil out the end of the hose, which ran into the valley behind the cylinders and then out behind the kickstarter cover onto the ground. The engine registered 150 psi on both cylinders and there was no visible smoke out of the mufflers, but something was pushing oil out the breather system. Although rarely discovered, if the breather plate drain holes are not oriented downwards, the trapped oil will spit back out of the hose. It seemed to be the only logical reason for the oil expulsion, so permission was granted to drop the motor down out of the frame so the top cylinder head cover could be removed for inspection. To get to this point the exhaust systems, carburetor and horn must be removed, the rear wheel loosened up for chain removal and the footpegs and right side kickstarter cover must all be dismantled. All motor mount bolts are removed except for the bottom two while a small floor jack lowers the engine assembly downwards.
Once the cap nuts and heavy washers were removed, the cover was gently pried off the top of the cylinder head. Sadly, the drain holes for the breather plate were exactly where they were supposed to be in the downwards position. All Honda Dreams have 360 degree crankshafts, so both pistons rise and fall together. This creates quite a bit of pumping losses inside the crankcase. Noticeable crankcase pressure was observed at the end of the breather tube, but it didn’t seem all that excessive. Still, after a high speed run, there was conservable oil deposited upon a shop towel left in place to catch the oil solids. Apart from tearing the top end of the engine off and apart, the Plan B was to run a long rubber hose from the breather hose back along the side of the chassis, to just past the left rear shock. A trial run proved that this was helping to control the oil expulsion for the moment.
Before the first test run could be completed it was determined that the clutch was “stuck” together internally. This is commonly seen when engines sit unused for many years. The fix is to remove the clutch cover, separate and clean all the plates and reassemble. The clutch plate cleanup, coupled with a new clutch cable gave an easy pull at the lever and a clutch which actually disengaged when the lever was pulled in.
Because of the sticking clutch plates, one must infer that the pistons and rings sat in one position for many years, as well. Often, the piston rings will become glued into the ring lands of the piston held with varnish deposits of old dirty engine oil. The end gaps of the rings are nominally around .008-.012”, but that gap is important so the rings can float around and close up at the end of the compression stroke holding the gases above the piston crown during the firing process. If there is excessive piston clearance or ring end gap, then compression loss and crankcase pressure increases can occur. Oddly, the compression readings are normal, there is no smoke out the exhaust pipe and the spark plugs are not getting oily, all of which might indicate that the pistons/rings are still in good condition.
From this point the possibilities are that the rings will gradually loosen up some and increase their tension on the cylinder walls or that the problem will worsen over time and miles. While hot oil and compression gasses might seem a good remedy for gooey piston rings, the same heating cycles can also cook the deposits into something more solid. Without tearing the top end down for inspection and measurements, we won’t know the real cause of the blowby problem.
In the interim, the owner has taken the bike back and will ride it locally, watching the oil level and spark plugs for fouling. This bike is a somewhat representative example of what you might find out there for sale on the internet or even locally. In many cases, you are better off to find an original, unmolested machine vs. a “restored” version which was done incorrectly by amateurs who do cosmetic freshening and perhaps a “top end” job, but fail to go deeper into the engine cases to remedy worn bushings and other critical components. Having documentation about repairs and maintenance records can go far toward ensuring that your vintage bike purchase is going to be a sound one. When in doubt, call an expert on vintage Honda motorcycles and have them evaluate a potential purchase.