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Can 120# compression = no idle?


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My 1992 CR250 still won't idle with the choke off...

I cleaned the carb with compressed air for the third time and adjusted the floats again to factory specs.

So now I wondering if ~120# compression(warmed up throttle open) can cause this?

Otherwise the bike starts and rus just fine?

What gives?

See link for what I have done so far...

https://thumpertalk.com/forum/showthread.php?t=895066

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Usually low compression will make it a little more difficult to start. 120 seems a bit low on the compression though. Have you messed with the air screw any. What is your jetting at? The air screw can also help with your idle. You may have the wrong size pilot jet. I would adjust your air screw until your idling rpm's pick up, then adjust your pilot jet accordingly.

Edited by KcDavis
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Hmmm.. the bike is very easy to start and runs fine. The carb is all stock as far as jetting etc... for the last 12 years with no problems.

I have adjusted the air screw from 1-3 turns out with no change and also the choke/idle as well . Now I am wondering if the crank seals I replaced "could" cause this this? The bike was fine before.

I guess a leakdown test is the next thing to do... dunno

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Maybe the choke/idle knob itself isn't working. Is the needle still in good shape?

What happens if you go more than 3 turns out on the air screw?

The choke itself seems to be fine, it does what it should on cold starts, but it is 18 years old so I'll probably change it out just to eliminate it as a problem.

It's been awhile since I turned the air screw out 3 times, can't remember what the bike did, but I do know it still would not idle.

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If you are kicking over hard and all you are getting is 120 psi., it's time for a rebuild. After a fresh rebuild should be at least 180 psi.

Oh I know that is a low number, I was curious if it could cause my problem.

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