Intake valves "kissing" piston...why?

Skidmark · Aug 23, 2009

Ok, so i put in a Pro Circuit piston in my 07 CRF150R and upon start-up, the intake vales were kissing the piston....just enough to make noise and some circles on the piston head. I rebuilt the motor 3x and it did it each time I would start it back up. Sooo... I put the stock piston back in and I got no further valve/piston contact until this weekend. I raced the bike a full weekend and it ran fine with no noise...this weekend was a open practice and the noise gradually started coming back. I pulled the motor apart last night and now I've got proof of contact with the piston again. Just the intake valves are touching.

The rod feels good on the crank and the piston....no noticable "loose" movement and no binding....everything seems as it should. Valves clearances are within spec (a few thou loose actually).

Any ideas?

Thanks.

Guest · Aug 25, 2009

Make sure you are setting your cam timing correctly. One tooth can be difficult to notice when lining it up but makes a drastic difference in actual cam timing. If it didn't do it originally when it was new then the cam lobes are probably degreed in spec just make sure your gasket thicknesses are the same and you are setting the timing correctly.

BlackBeard · Aug 26, 2009

do the crf150's have the pressed on timing gear? I remember reading somewhere about a recall because the pressed on gear was actually moving on the camshaft and casuing this same symptom?

schofell84 · Aug 26, 2009

could the valves be getting ready to pull apart?

Skidmark · Aug 31, 2009

Supposedly the recall was done prior to purchase....I'll double check this.

Timing is perfect.

Gaskets OEM and brand new.

Thanks for helps so far. No solutions though...

Skiddy

Intake valves "kissing" piston...why?

Skidmark

Guest

BlackBeard

schofell84

Skidmark

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