Topic: Oil Leak from the exhaust on cylinder 1- '71 CB750

[m.luster578]

I haven't been able to get under the valve cover because of one stripped alan key bolt that I've been messing with. But now I have the exhaust off for that one side and it seems to only be leaking from one but I've been trying to see why. This bike needs all new gaskets all around the bottom end but before it was in pieces, when I gave it gas it would splatter from cylinder one when the other leaks was just dripping.

[flybox1]

I would bet it was condensation.  Not oil.

[HondaMan]

Could also be a real bad exhaust valve guide, lots of clearance. The K1 has no valve seals on the guides, which are made from Stellite: if the engine sat a LONG time with that exhaust valve open, it may have rusted enough on the stem to make it slow to close. Then, when the engine is forcibly reawakened, the piston hits the valve and cracks or chips the glass-hard Stellite. Then a nasty oil leak can ensure

(Seen this quite a few times since the 2000 era of reawakenings began!).