Dominator smoking
 

Hi i need help my 95 Dominator 650 smokes (blue) about 15 seconds after cold start up, then clears after 20 seconds, this is the only time it smokes, i have overhauled the cylinder head with new valves and seals, also the guides have been checked. There are no wear marks on the bore so dont think it is rings, engine has only done 20 000 miles. My thoughts are a problem with the oil pump non return valve leaking and letting excess oil to drain back in to the engine when it is standing. would appreciate any comments. Thanks Andy

The only way oil can get into the combustion chamber is past the rings past the valves or through the cylinder head. so check/service those bits no matter what your oil return valve is doing.

the valve is spring loaden and the springs can wear out but 20000miles seems to me a bit early
i should not worry about it to much, just make sure you don't run out of oil or you might get into expensive trouble
if you dicide to work on it...do NOT forget to bleed the oil pump before start up!

Oil is getting inn!
 

Obviuosly some oil is leaking in,i have an XR 650 L(same engine).Recently overhauled all the upper part.Had the same as you.But after new piston,rings,valves,seals and mechaniced the valves seats,all gone.
No more blue smoke at start.
Did you replaced tha parts or like in my case an experienced mechanik?
Good luck
KH

Check your plumbing
 

Aha! Had the same problem with my 93 dommie after a top end rebuild. Had me scratching my head for a while until I rechecked the pollution cannister next to the carby. I had inadvertently kinked the top pipe when fitting the clutch cable. This created a vacuum and sucked sump oil into the airbox and hence the combustion chamber. Simple rerout of the pipes and everything smells sweet once again....

:thumbup1: Smoking now fixed, i replaced the non return valve, spring and seal in the oil pump, valve was letting too much oil drain back in to engine, so giving high crank case compression until the oil pump managed to return excess oil back to the tank.