I decided to do a bit of digging into why the motor on this thing doesn't run quite as sweet as it should, so I did some unbolting and was able to turn my motor assisted bicycle into just a bicycle.
The cylinder barrel was de-carboned and repainted, the head cleaned up and the compression release replaced, and new gaskets all around. I was curious as to why the compression release didn't seem to work, and it turns out the air passage from the valve to the exhaust manifold was completely plugged. In addition, it looks like a PO adjusted the valve itself to open WAY farther than it was supposed to (I'm guessing to counteract the non-functional release), to the point where it would make contact with the piston if it was moved too far. I've still got to nail down the exact adjustment, but I can at least get that taken care of. I also was able to clean out the carbon buildup in the exhaust port itself.
The fuel pump got a new diaphragm and plastic backing plate, and everything was cleaned up the best I could. It really is a neat little motor. Unintuitive, a pain to get apart in spots, absolutely baffling bolt placement in others, and a mounting system to the frame that's complicated to the point where even after I've gotten it off I STILL don't entirely know how it works, but neat.
Speaking of weird, this is the carburetor. As it sits in the photo, fuel come up from the bottom on the left side, and air comes down from the top on the right. Air and fuel mix in the center crossover (there's a jet in there, on the backside), and the air-fuel mix exits into the engine out of the bottom on the right. The best part is there's no fuel bowl- any excess fuel exits out the tube on the upper left to drain directly back into the fuel tank. Oh, and the throttle linkages (currently removed) set the carb to wide open when at rest.
As far as the rest of the bike is concerned, I'm going back and forth about painting it or powdercoating it. Paint would be well inside my current budget, but this thing is enough of a pain to take apart that I really should do it right the first time. Problem is, my normal powdercoat guy is backlogged on projects due to Covid, so he's stopped taking any non-industrial work for the forseeable future.
(shrug) Who knows. I guess we'll see.
), possibly some spokes as well, along with all new control cables- a PO at some point completely butchered the throttle controls. (In their defense, it seems like every spring and throttle control is there to get the engine to throttle DOWN, rather than the usual up. I can tell this is going to be fun.)
