I have a 99 400ex (stock everything).The baffle removed.After a high speed run,letting off the throttle results in a slight bit of blue smoke from the tailpipe.No smoke at idle or any other time!! Valve guide seals??

 

Is the choke stuck on a bit? Maybe the cable need greasing.

 

Sounds like guides are worn or seals are bad.

 

could be a yery small piece of one of your piston rings broke off and only at high rpms oil gets through and that is whats making blue smoke thats what happened with my suzuki 230s

 

be28936...the choke is butterfly valve with a switch directly on the carb...so unless that is broke it cant be that...for blue smoke it can only be valve seals or worn rings....if ring was broke he would be lossing power along with smoke...imo...hope this helps

 

the 400ex's are known to use a bit of oil when ran hard. try switching brands of oil. most don't have a problem once they switch oils. i haven't heard of any problems with people running the mobil 1 15-50 full synthetic. this is what i run and don't have any problems. this oil is now discontinued so we will have to find another good one.

 

Thanks for the help everybody!! guess i better dig deep in my pockets for this repair!!

 

really u dont have to dig deep ring are very cheap and gaskets are nothin its just finding someone to put it in for u cheap.