I have dicovered a problem with My NC-29 Race bike, It is running rough at idle and also when you rev it while not in gear.

It was fine at my last track day which was around 2 months ago.

I have run all the electrical test and they seem fine and have also stripped and cleaned the carbys but i did a compression test today and found that Number 4 Cylinder basicly had no compression.

This seems weird because i took it for a quick ride and once you get going it feels fine?????????

I am planning on taking the motor out and checking shim clearences etc.

Any ideas.

Parto

check the clearances is a good start(considering no compression)
mine had a problem running on 3 cylinders at idle but went well,turned out that the pilot jet was blocked again.
if all checks out good,its time for a rebuild.
stimpy

hvae you tried checking the compression after suirting some engin oil down the appropiate spark plug hole then rechecking it again ?, this would tell you if its a ring or valve problem , also worth doing a leak down test

Eddie

valves would be a good bet
Also - leak down testing - will show where the problem is: valves or rings

I have now done a leak test and found that the inlet valves on cylinder No 4 are leaking so i'm taking the head off and rebuilding it.

Cheersparto