Compression tester, Please Sir, can I have some more?

[xwhatsit]

Hihi,

My engine is a paperweight, I think. Long list of symptoms, but I'm suspecting burnt valves, or some other valve thing. No smoke, so I don't think it's rings or piston. I have another engine lined up thanks to a KBer, but I would like to know what's wrong with my existing mill.

Hence I would love to be able to do a compression test. They seem to be >$100, which is money I don't have. Does anybody have one I could borrow in Auckland? The spark plug is an NGK D type, which is a 12mm thread.

Thanks so much.

Cheers,

-Tom

[Squiggles]

bump for ya

[xwhatsit]

Cheers buddy -- should have posted a follow-up that I'm sorted. Will know the verdict by this weekend.

On a related note, has anybody got one of those fancy advancing ignition testers? My uncle has one of the very simplistic old-style ones, but an advancing one might make my life a little bit easier.

[xwhatsit]

Well just did the test. Thank-you Mr KBer :)

I'm slightly confused. My engine got just under 100psi with the throttle closed, but when I opened the throttle (as a couple of internet sites told me to do for a correct reading) I broke past 170psi. This was easily repeatable -- decompression cable on or off.

Am I doing it right? Throttle wide open, four or five kicks, check gauge? I was under the impression that I should be looking for at least 100psi, maybe 150psi max, not 175psi. This is with an old engine with no valve grind, rebuilt with original piston/rings. Only 9.3:1 compression ratio. The gauge seems decent, made in West Germany.

Oh well. It seems like there's plenty of compression at any rate. Time to look at the ignition timing.