It is probably nothing important and just shedding some oil that has collected in the head. Changing the brand / weight of oil used might stop the engine from doing that.
Usually, smoke that appears when the throttle is closed, and a high- vacuum condition is created, is the result of loose valve guides / seals and oil is getting sucked into the intake. Bad ring seal on the pistons usually results in producing smoke when hard on the throttle but not when the engine is under little or no load (such as when you close the throttle to shift). Unfortunately neither a compression test nor a leak down test will detect loose valve guides because both tests are done when the valves are closed.
As someone already said, check the spark plugs for any signs of fouling. If they, or one, have excessive carbon build- up, it might be time to check the valve(s) stem(s) for proper clearance and the valve seal(s). Another sign of loose and leaking valve stems is wet oil accumulated in the exhaust ports or very early in the exhaust system but that only works if the bike has been ridden relatively lightly so as not to heat that oil up enough to dry out and cook off. Valve stem clearance is a manual check, done by trying to rock the valve in the valve guide and watching the movement with a dial indicator. Any of that would be covered under warranty if the bike is still under warranty, and perhaps even if it is not- valve guides should absolutely not fail in 30K miles.
Again it is probably nothing though and unless there are other symptoms or excessive oil consumption, and the engine runs correctly and strong at all RPM’s, I would probably ignore it once the bike has been through major maintenance and everything looks fine.
Brian
I was riding today with two other c-14's and my buddy Cablebandit told me that my bike was blowing smoke out of the exhaust every time I upshifted. The motor still runs strong - just blowing some smoke. I have the full system from fuel moto installed, the map Jamie loaded when he shipped the pc, no flies. Any idea what could cause this? JamminJerry said it may be loose or tight valves? I hope it is something simple like that. I have just over 30k miles on her so she is due for service, but I would like some input from the mechanical genius's on this site so I can ask the correct questions when I talk to the mechanic. Has anyone else had this happen? If so, what was the cause?
Thanks in advance for any input.
