temp for compression check?

kismetologist · Posted: November 21, 2007, 4:34 pm Post subject: temp for compression check?

Can anyone tell me what engine temperature should be when doing a compression check?
I've figured out that it should be a warm engine, but how warm? and is a 40 psi jump a bad sign when you do a wet test (oil in the plug hole) even if the dry reading was in the normal range of 120 to 130 psi?

xsjohn · Posted: November 21, 2007, 9:32 pm Post subject: Re: temp for compression check?

Mine were 150 psi after maybe 8 thou on new rings old pistons.......don't think I had warmmed it up.......can't really remember......trottle wide open and I didnt raise or remove the slides which most people reccomend.......

I think 120-130 is kinda low........

The oil temporarily seals the rings. If the readings are higher the second time around, it means the rings and/or cylinder is worn. No change in the compression readings tells you the cylinder has a bad valve.

John

What Happened to 650rider.com?

Yamaha xs650