proper way to check compression ?

thirtyfour

Member
Oct 27, 2003
34
0
ok , here it goes,
after the recent jetting change , I pulled the spark plug to check to see how my adjustment payed off. nice and deer brown pug tip and insulater.
figured this would be a good time to check the compression readings.
used a regular automotive type compression gage ,
engine cold , fuel off, trottle open wide and gave it several good full kick..... each kick resulted in higher reading on the gauge, it settled around 210 PSI and I got tired of kicking.
can this be correct reading for a KX250 ?

thanks
 

rairden

Member
Jun 3, 2003
74
0
Yes it can be. I have a new YZ250 and w/ a cheap($20) tester I got 235psi.
And for my new RM125 I got 205psi. But that is w/ a very cold engine, 10 degree weather, and a dirty filter.

I heard you want to be btwn 180 & 230psi. Somewhere around there. And the compression isn't a true reading of the engine health. I don't think---just a diagnostic tool.
I'm just taking guesses, BTW.
 

Vytas

LIFETIME SPONSOR
Oct 31, 2001
256
0
My 250 is always about 210psi after a new piston change.
 
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