Compression Testing

When testing the upper compression on a two cyl. motor do remove one plug at a time or both? Will you get a diff. reading doing it o :thumbsup: ne way over the other? Thanks.

I've heard of it both ways. The theory of leaving the other plug is that supposedy when it comes off tdc compression it will accelerate the upstroke of the gauged cylinder. I tried it, just made it harder to pull, got simular readings. Give it a shot, see what you get. I had an interesting thing happen of note. Engine stone cold, oil film on cyls thick and "unbroken", screw the tester into the pto, pull it 3-4 good times, 135psi, move to the mag, 130psi, why the hell is this thing down on the mag, its a new build? next cold morning, do the same test starting with the mag 135psi. pto now 130psi. they switched! the only thing I can figure is that the first test "loosened" the oil film, so the second test din't seal the rings as well? I now start the engine then shut it right off before a cold test.

Originally posted by hillpounder@Sep 21 2003, 03:53 PM I now start the engine then shut it right off before a cold test. That's the way I do it. Seems to make for much better consistency.

I have the same problem but no deal I have called have any rings until oct 19, does anybody know where to find them I am trying to race on sat can anyone help with a solid lead where to find them call me at 508-450-8294 (cell) Bubba

Your response doesn't really apply to the original post, but if you want to e-mail me, I will try to help you out.