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What compression should my 2000 KX250 have?
Posted: Wed Jan 30, 2013 10:32 pm
by Tardboy
What compression should my 2000 KX250 have?
I put a gauge on it and it only reads 120 psi.
Is this ok?
Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 2:39 am
by Sandblaster
For 92-00 KX250 it should be 780-1220 kPa or 114-176 PSI
So your a bit on the low side.
Didn't you just put a new top end on it?
Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 2:49 am
by Tardboy
It's been about 2 seasons worth of ridin.
Looks like I got to do a top end and I'm broke

Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 2:51 am
by Sandblaster
Just thinking out loud here, when you did your compression test did you hold the throttle all the way open?
Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 2:53 am
by Tardboy
Wait, hold the throttle wide open?
No, I didn't open it at all.
Would this make it read low?
Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 2:56 am
by Sandblaster
If you didn't hold the throttle open then the engine could not suck in enough air.
So try it again and see what readings you get.
My bet is you will gain 20-30 psi.
Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 2:57 am
by Tardboy
Ok, I'll get the tester tomorrow and try it again.
Thank you!!!!!!!!!!!
Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 3:02 am
by Sandblaster
No problem, hopefully this will help.
Curious as to why you ran the compression test to begin with?
Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 3:07 am
by Tardboy
Oh, ah it was because it seemed to loose a little power an when it idles it runs too fast so I adjust the idle and then it runs fine for a bit and then it is too low.
You think I need to jet it?
Re: What compression should my 2000 KX250 have?
Posted: Thu Jan 31, 2013 4:39 am
by Sandblaster
Honestly, it sounds like a air leak or your jetting is too lean.
But if I had to guess I would say air leak.
Did the bike run fine with the current jetting before you started having surging?
How does your boot look?