I just picked up a compression tester at an estate sale, so I have to admit it could be off. but the fellow was an mechanical engineer for NCAR here in Boulder, and had soldered the free spinning end of the hose even, so I assume he knew what he was shooting for. still in the original package, tho well used.
I also don't know what my compression ratio is supposed to be, or what it actually is. I have a 57 spitfire scrambler by the factory records for engine and frame numbers, but it could have had lord knows what done to it. I've thought a lot of things were in really bad shape, but they turned out to only need minor attention for the most part. I think that someone who ran this bike really knew what they were doing. (that wouldn't be me)
but I tested the old gal tonite, the altitude is 5300 or so, and it was raining pretty hard on a new storm just started. what that might mean to the atmospheric pressure is beyond me?
but anyway, it tested at 120 psi. took four to five good kicks to get it up there, and the engine was cold, but both sides were spot on at 120/119.
I have to say I was pleased after having been told of the smoke on my right cylinder recently.