Going to compression test bike

[Bandito]

I've read that 150 psi is the normal but what is cut off point for bike needing work? Does it work like that?

If mine say was 112 would that mean it's time to investigate?

Also the kit I've bought looks like same thread isn't as long as the spark plug thread is that going to make a difference to my results?

Sorry for all questions new to engine works/ two strokes

Cheers


Matt

[fallenmikethebike]

The thread length shouldn't make any appreciable difference.
Test on a warm engine, ignition off, fuel on, throttle open, kick away, half a dozen times or so.
Check the reading, and repeat a couple of times, average out the result.
If it's in the 130's or lower it's time to start thinking about a top end freshen up.
I.M.H.O.
Mike

[Bandito]

Thanks for that Mike, would the cold engine versus warm engine have a big difference?

Why do you test with the fuel on if it's not going to be igniting it?

Sorry for all the questions

[fallenmikethebike]

Thanks for that Mike, would the cold engine versus warm engine have a big difference?

Why do you test with the fuel on if it's not going to be igniting it?

Sorry for all the questions

Warm because that's the ambient temperature when the engines running.
Fuel on, because it will help seal the the rings, and again, fuel would be in when the engine was running.
Others may have alternative view points.
Mike

[Bandito]

OK Mike cheers I can understand the warm part as that's how it will be when riding, so simulates the same.

See if anyone else says how they do theirs.

Thanks for help

[knackeredMk1]

No Mike you will get the maximum possible compression using the method you have suggested.

[gregorious77]

pretty sure it should be up around 170 psi

[Bultacobob]

My bike (MK3) is a low 4000km and reads about 175 psi. I reckon this is around the top reading.
Hope this helps.

P.S Mikes method for the reading is spot on in my opinion but try with throttle fully open.

[gregorious77]

rebuilt mine at 12K miles and it was 125psi