How much compression should an 04 crf450r have?

78psi is the MINIMUM service limit spec. and accounts for the decomp. I just checked mine after 75+ hours and it had 82 per my gauge (not super expensive, but +-1 to my builders SnapON 200$ gauge. Won't see much more than that even with a new top end. The manual says have the throttle held wide open. not sure it matters much closed or open, and i didn't see a diff with opne closed, and do it with the motor warm. I have seen a a minor diff in a cold motor vs. warm. Don't put any oil in the cylinder, just run the bike, the do the test.

Keep in mind for those reading with 03 or newer, the min spec is a bit less.. ! So don't be alarmed. I think it is 65psi min for 03 and 02 but don't quote me on that..

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