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picked up a 1997 CR125 that doesnt want to rev out

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First off it feels like very little compression (which may be related). Ive cleaned the jets out and that did help a little. Could it be anything else carb related (air screw)? I think I recall the jets being 420 and 170 ( (didnt think to check and make note of the sizes as they could be wrong). Do I need to change the needle clip setting?

OR, is this a power valve issue? It kinda feels that way as the power doesn't really seem to come  at the top end (it does have a decent little midrange hit)

It's also leaking coolant on top of the right side of the cases behind the expansion chamber somewhere. Will address this when rebuilding the top end I guess...

Cylinder has a "PR" cleanly dremeled into the left side I guess meaning someone ported it at some point. Previous owner was completely oblivious to anything mechanical.

Edited by 831Honda
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Sounds more like the HPP (powervalve) isn't working. If you have no top-end it might not be engaged correct and might not open which could be the reason it won't rev. You definitely need to heck my thread about setting the HPP here:

 

But anyway-get the top-end done and check the waterpump since that's where the water seems to come out. There's just the waterpump behind/below the exhaust to the right side of the bike.If the leakage is farther up it has to be the head gasket.

The airscrew has nothing to do with your missing revs, nor the needle.

On a stock carb the main jet will be around 170-175

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On 5/22/2017 at 10:44 PM, nino said:

Sounds more like the HPP (powervalve) isn't working. If you have no top-end it might not be engaged correct and might not open which could be the reason it won't rev. You definitely need to heck my thread about setting the HPP here:

 

But anyway-get the top-end done and check the waterpump since that's where the water seems to come out. There's just the waterpump behind/below the exhaust to the right side of the bike.If the leakage is farther up it has to be the head gasket.

The airscrew has nothing to do with your missing revs, nor the needle.

On a stock carb the main jet will be around 170-175

thanks for that good info. ill have to open those up and take a look. if it is the water pump what causes the leakage there, just a gasket issue?

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