I've been rebuilding an NC23 and I've come into some issues I can't seem to fix. I'm no expert when it comes to carbies so I'm not really sure what the issues could be.

The problem started with the bike refusing to start and the carb overflowing. I stripped the carb down cleaned it and reassmbled it. I managed to fix that issue but now it won't idle and constantly surges. It surges between idle and 4-5k (I'm not 100% if the revs are accurate as its got aftermarket clocks on it) does anyone have any suggestions on where to start?

One of the float chambers is leaking, but from my understanding that shouldn't cause this?

Air leak

thunderace wrote:Air leak

So I'm assuming that would be from the rubber boots between the bottom of the carby and the engine? I've ordered a new set off ebay. Mine are more like wood then rubber.

I've sprayed "Start ya Bastard" (not sure if its an Aussie only thing but its an easy start spray) around the base of the carb and normally I'd expect to notice a change in RPM if there was a carb leak but there was no change. Is there anywhere else that you'd expect an air leak from?