Low compression

[zerolander]

My first post because I'm baffled. New rings with piston diameters within service tolerances. I can only get about 40 psi compression. Piston and new rings are very snug in the bore. I've been told to check crank seals, oil pump, and crankcase for leaks. I'm baffled because that last inch of piston stroke should be the only factor affecting compression. By the way the crank seals are good. I have used soapy water around the head to cylinder and cylinder to crankcase seals. No bubbles why cranking it over. I checked my pressure gase with an air compressor - it's good. Thanks

[fastplastic]

Try the oil trick which is to add a few drops and retest compression also remember to hold throttle wide open when texting and to kick till the needle stops moving

[Pete M]

Are you sure your guage is accurate?

[fastplastic]

I have a feeling he is taking the test as if it was a four stroke

[r2dillon]

Is compression testing different for a single cylinder?

[Pete M]

For a four stroke you use your index finger and for a 2 stroke you use your thumb

[fastplastic]

All that using ur fingers does is test to see if there is a ring left in the motor not accurate enough to tell u if u have enough to run or not

[abreen89]

For a four stroke you use your index finger and for a 2 stroke you use your thumb

just get one of theses before i crack a rib hahahahha http://www.harborfreight.com/compressio ... 66216.html