Breather tube steam cleaner?

[Loudo]

This regards the '63 CB77 entitled "Fresh Meat" in the Restorations forum. Motor seems to be running fine, at least both cylinders seem to be firing adequately and it drives and accelerates with no problems, plenty of power. I took it on a twenty minute drive yesterday, got it good and warm to see if I could determine the effects of messing with the air jets and slide screws. I was encouraged to see no oil leaks. However, while it was idling I noticed some moisture around the left side center stand foot. I peered under the bike and noticed my breather tube which is routed to this location was spewing vapor like a tiny teakettle. It wasn't noticeably hot, and it wasn't really emitting actual liquid, but the vapor was condensing and running down the center stand and it looked like tea would soon be available for some tiny people. Under what circumstances, I hesitate to ask, would one expect this to be happening?

[e3steve]

It's a breather; it's breathing.

Excess crankcase pressure, chuffing like a steam loco, would be a sign of head gasket failure or piston blow-by. I'd doubt the former is the case, and the latter is possible, but it sounds to me, from your description, pretty normal.

[Loudo]

Thanks, Steve. I suppose the ultimate test is whether the bike, er, "fails to proceed."

It's not "chuffing" so much as just a steady stream. I'll keep an eye on it.

[e3steve]

Neil, the temperature change within the crankcase has to expand to someplace, so I really wouldn't worry at this stage. If it was chuffing, that would indicate a degree of pressure build-up from the cylinders.

A stream of vapour indicates expansion, which is natural, IMHO.