Why Is There Oil Under The Rotor Cover?

Please, feel really stupid...why is there crank oil under my rotor cover? Is it suposed to be there? I am installing the 10 oz rotor on the YX400 F and oil dripped out like it was a sump! Is there a seal that has failed or is it suposed to be there? Bike runs great, no problems...

Either I don't understand the 4 stroke or something is terribly wrong... Help would be appreciated...



76, 77, YX80's

1999 Yz 400F

It is the sump. The left main bearing and balancer shaft bearing live there.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now