Well, I could definitely use some help with a mysterious problem.
What I have is a 1987 K75C I've recently acquired as a fix-up project that exhibits a very strange pattern of smoking--it doesn't make the puff on startup that the bike is known for, but rather starts up smoke-free and after around thirty seconds or so starts to smoke badly. Makes me think that it isn't an issue of oil seeping past the rings (it's on the centerstand). The smoke is bluish. If I let it sit ten minutes and start it again, it's smoke-free for the better part of a minute once more.
The bike has 65k miles, and compression seems to be excellent: 190, 190, 185 psi. I recently went through the intake and replaced the rubber boots between the plenum and the throttle bodies as well as the crankcase breather hose. When I did, I found that the air filter was completely soaked in oil, and oil was being sucked down into the intake. I thought I had found the cause of my smoking, but cleaning it all out hasn't stopped it. In fact, aside from some severe stumbling off idle that I've improved with the new rubbers, the bike runs about exactly as it did when I first got it.
I was thinking I might have bad valve stem seals. I'm really not too sure what to make of it. Any thoughts? I'm happy to provide any other info that might be illuminating.
