Problem after 426 rebuilt.

[kubamtx]

Hi

I've got one problem in my 01 yzf 426 . I've rebuilt the bike few months ago. Now it has about 30 hrs. I've re-ruted breather tube and today I've checked the air filter on it and found pretty much oil on it. I've took the filter off and started the bike and noticed that there is a lot of air pump duting idlig. Is this normal? I don't remember such a high air flow before rebuild.

Please give me a hint. Shuld I be worried?

[642MX]

I wouldn't worry. They all have blow-by, even brand new bikes. If you over fill the oil or run the bike real hard, its normal to blow a little oil out too.

[kubamtx]

I've notice oil after hard rides. And I have 10 km from track to home and I always do insane speed enduro when arriving;-) Maybe that's why there is oil in breather. Bike is running strong and clean. I knew that ther is air move in breather on idle but now I think it is even bigger.

[grayracer513]

your bike is a 426 because that is the volume of air displaced by the top of the piston as it moves from bottom to top. What most people don't hthink much about is that the bottom of the piston displaces the same amount as it moves from top to bottom. That air has to go somewhere.