i have taken my mc18 r2j out of the shed for a freshen up before summer.

i replaced fork seals today and my back shock is shot so i am replacing it tomorrow.

i checked the compression with the engine cold and i got 140psi on the lower and 130psi on the upper cylinder.

i left the bike warm up to around 65 degrees and i got 120psi on the lower and 110psi on the upper cylinder.

i thought the compression would be better when warm .

Sounds about right. I got a similar reading when I tested the compression on my newly rebuilt engine.

that great i thought i was having problems

I'm not sure of the reason why it would be lower when warm. I only tested mine cold.
Both cylinders should read almost exactly the same. Yours aren't too far different, and still have good compression, so I wouldn't worry.
How many kms has it done on those rings?
Have you taken the pipes off to check up the exhaust?
To replace the rings if you so desire is cheap as chips.

Just out of curiosity, what are you replacing your rear shock with?

OEM shock (new?) or aftermarket?
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PROSPEC QUARTER !!

i dont have the bike long i have done around 2k kms on it and i am not sure about when it was rebuilt.

the clocks read 19000k kms.

the bike has had a full engine rebuild in the past i can see that because the gaskets look clean.

i have looked up the exhaust ports and the piston look clean and the bore looks good, but the top of each piston is a light brown colour not sure if this is normal or not?.

i thought i had leaking crank seals but it was only the rear shock leaking and was covering the inside of the fairing in oil and some found its way onto the engine.

i have replaced the rear shock with another used oem mc18 shock i have from a donor bike.

i also noticed that the lower cylinder exhaust gasket was leaking i have replaced both gaskets and the bike runs much better now you can feel the front trying to lift when the powervalves kick in in first gear .