what do you mean rings are bad? what rings???... it happened to me again so i just took the crank case hose and disconnected it so it wont spit out oil into the air box but how can i get this to stop?? just put in an 06 carb in my 03 400ex is that bad??? its running fine but it redlines to much like it wants more. my jets are jetted to an aftermarket exaust and im alll stock is this also bad?? please help me

 

your rings in the engine, the things that give you compression? between the piston and the cylinder wall. do a compression test on the cylinder...anything less than 100psi is bad...

 

Friend I hate to tell you this but you have a ring problem. Not really that bad though, replace the piston rings. If you need an air breather buy one, that is prolly what caused your rings to wear out.

 

Had the same issue on a 300ex, after mush confsion and testing, ended up being timin chain jumped a tooth. had to replace timing chain and related parts.