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Compression test

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Just wondering how to perform the test and what are the numbers im looking for, whats good and bad?

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To do the compression test have throttle wide open and the killswitch depressed. Fresh air filter. Kick until number tops out.

Compression numbers will vary greatly depending on temprature,altitude,compression tester,size of bike,head space.

Generally speaking 175ish psi is what I get at 3000 ft. on a CR250 with wiseco prolite piston.

125ish PSI for CR125 same conditions.

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My altitude is 0ft. So thinking a basic rule would be, measure the PSI when the top end is new and replace top end when it goes drops so far?

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i got 160 out of my cr125 cold, i believe anything above 150 on a 125 is acceptable

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My altitude is 0ft. So thinking a basic rule would be, measure the PSI when the top end is new and replace top end when it goes drops so far?
Reputable people have posted that when compression drops 10% (compared to a fresh piston), you at least need new rings. To be on the safe side, replace the rings and piston after the compression drops by more than 10%.

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I just did the test on the fresh motor, i got 190PSI.

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