03 CR250 Cold Engine Knock

[dekker]

Hey guys,
I was wondering if anyone could help me out on this one. I have an 03 CR250 starts great and runs strong, but when the engine is cold it knocks at idle. Once it warms up maybe 2 min later its fine and sounds normal. Anyone had similar experience?
Thanks for the info
Zach

 

[IndyMX]

Maybe the piston is rocking in the cylinder, but when it warms up a bit it expands enough so that it stops??

Probably time to do the top end. Also want to measure the bore for proper clearance and roundness.

 

[dekker]

That was my first thought. It literally only does it for a minute then goes away. The motor runs great and starts first kick off the choke. Its not terrible i'm just a perfecitonist when it comes to my motor.

 

[colotowyo499]

Don't forget to check the con rod and bearings if you do tear the top end apart, kind of sounds like a rod knocking just from description

 

[jaguar]

Play with different air screw settings to see if it is too rich or too lean at idle