Best way to check compression?

[Madbuffalo]

With my dirt bikes I've always warmed the bike up before testing cylinder compression, then checked at W.O.T. Using the same process on my 3 cylinder GT750 is not working. When I warm the bike up and test compression each cylinder reads lower than the last and going back to the original cylinder tested gives the lowest number yet. Basically, the engine is cooling too fast for me to get accurate readings. Is it better to test when the engine is cold, knowing that the numbers will be a bit lower? This has kept me from checking compression on a regular basis which I'd like to be doing. What do you guys do?

[tz375]

I just check it cold, WOT and kick or push button until it stops rising. I have never tested a stock motor. My last bike was 150 ish and this one is 165 or thereabouts and it's "almost stock".

[Madbuffalo]

Thanks Richard. Getting 165psi on an old GT with nearly stock engine you must be doing something right.

[tz375]

Thanks. I think it was the metal that was machined off the head and barrels

[oldjapanesebikes]

Fully stock seems to typically run between 115 and 130 psi or so - 165 psi would be the 'enhanced' version !

[tz375]

Hmm. What's that old expression. Ah I remember. Nothing exceeds like excess... Or something close to that

[Madbuffalo]

Well I finally got around to checking compression. L=152, C=150, R=156. That's with a fresh rebuild on a completely stock engine (as far as I know) so I guess I'm doing something right too. Thanks for the help!