I rebuilt my 87 warrior motor about 6 months ago, and it runs well. Recently though everytime I start it up it smokes quite a bit, a minute or so later the smoke stops and all is OK. It still runs as good as before (no power loss that I can tell). My thoughts are that it is valve seals have gone bad. Is this correct? Is there a way to test for this and make sure this is what it is? Or do I have to pull the head and inspect. Anybody else have this happen? Any advice... Thanks GJ

 

I would do leak down test to check and see if your valves are seating properly, etc.

It almost seems that something(valves) are not seating until the machine warms up. But Your bike would probably be giving you some signs like knocking, banging, popping..hard starting.

 

Good call on your diagnosis.

Oil smoke on startup is almost always an indicator of worn valve guides or worn/hardened seals. The oil leaks down onto the piston and or valves as the engine is sitting, then upon startup, it burns it off. Usually the seals or guides don't leak enough to produce any appreciable amounts of smoke during normal running. It shouldn't really affect the way the bike runs, only possibly carboning up the intake valve and combustion chamber more quickly than normal...

Really, the only check I can think of, is to pull the head, maybe someone has a hot tip for checking guides or seals?