Have a misfire on cylinder 3,up to 2,000 revs it's very obvious,above this the bike seems to rev ok,had recent spark plugs,swapped everything around that can be swapped,fault still there,I recently had the carbs apart, fitted correct jets, new float needles and seats etc. I have a nagging doubt about the float heights.

Grateful for any advice

socket13 wrote:Have a misfire on cylinder 3,up to 2,000 revs it's very obvious,above this the bike seems to rev ok,had recent spark plugs,swapped everything around that can be swapped,fault still there,I recently had the carbs apart, fitted correct jets, new float needles and seats etc. I have a nagging doubt about the float heights.

Grateful for any advice

nc30? floats heights should be 6.8mm

is this the cylinder with the vaccum hose for the fuel tap? its not split / missing / leaking vaccum on that cylinder is it?

compression test could reveal a low cylinder compression but this is unusual, go with simple things first.

Sorry,yes it is Nc30, sitting on the bike its the rear left cylinder.