Clarification, Please. . .
Sorry to hi-jack, but I've had the experience of "using an auto (?) compression tester" on both an old LOW mileage, pampered Honda Goldwing, which displayed cylinder-level psi figures that were about HALF what they should have been, but the bike ran (still does) like a scalded-ass ape, a fact which told me "not to worry" about the psi readings. (Yes, I did the test properly, I think. . .) Recently, I just had the SAME experience on a '78 R100RS -- that is, readings of 85 on one side and 90 on the other, but the bike runs great - good starting, strong pull in all gears, and tops out at 115-120mph indicated.
[B]Paul [/B]-- are you saying that ALL airheads need to have the carbs REMOVED to get an accurate reading? Some source I read said that "only the 60's" need to have the carbs REMOVED, whereas for the larger-displacement bikes, all that is required is that the choke be "off" (plate open) and the throttle plates opened at the throttle to do the test. Maybe not enough air coming in with carbs in place to get accurate reading for ALL displacements?
Also, I understand that a "leak-down test" is MUCH more valuable vs. compression testing, as it really pinpoints the potential trouble-spot. I've never done this, but am tracking down a gauge and compressor right now to see how it comes out.
As always, THANKS to all the knowledgeable folks posting here. A guy can learn a lot, every day.