cream coming from the valve cover vent tube??

2 replies to this topic
  • DukeD

Posted December 17, 2010 - 10:48 AM


Hey all, I have an 03 yz450f set for supermoto. At the last trackday I noticed a little cream coming out of the valve cover vent tube. Immediately thought I had water in the oil but upon checking the dipstick the oil was perfectly clean? I've heard from some that this is normal and others have told me that I have a base or head gasket leak, can anyone shed some light on this please?

The bike was running great at a prior trackday except it was backfiring alot. Checked the pilot jet and found it was stock so put in a larger one to match the one over main jet and the duback pipe. The backfiring on decel is gone but then the bike didn't seem to have as much snap. I think it was due to the pilot being now too big since the dealer only had a 50 where stock is 42. I thought I should install a 45 or max 48 but since they were out I opted for the 50 just to see if the popping backfire would go away. It did but now I don't have as much snap. I'm hoping the loss of snap is from the pilot being too big and not from the cream indicating a bigger problem.

what do you guys think?

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  • William1

Posted December 17, 2010 - 05:56 PM


The 'cream' was probably just condesened moisture accumulated since the last shut dow. I assume it went away and there was no sign after a half hour or so.

Going rich on a pilot jet (which is for idle only) to deal with a decel problem, gave you a new problem. Go back to the correct pilot, set the fuel screw correctly by the accepted method and live wit the popping ot get a muffler to muffle it.

These are two entire unrelated problems.

  • DukeD

Posted December 18, 2010 - 06:25 AM


Thanks William1, once I discovered the cream I shut the bike down for the day so didn't give it a chance to dry up. I'll run it, and continue to check the oil. On the pilot jet I'll install the 45 and report back on the "snap" coming back too.

Thanks for the good news :excuseme:

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