Hey gyys, have an NC30 and NC35.. was having probbs with the vfr carbs so i swapped the rfv ones onto it for problem elimination purposes, anyway put the carbs back on the rvf and shes not running right.when it starts cold there is no problem but after 2 mins or so she revs uo to about 4000 revs ans stays there. i took off and replaced the carbs /airbox everything and im fairly sure its not sucking air, what else could it be?? has anyone had this prob before??/ any help much appriciated.

Hi,
I reckon the first thing as you say is air leak, but if you are sure thats not the problem then it could be you have moved one of the balancing screws whilst taking the carbs off.
Is the vacume hose in good condition?
Does it just hang at 4k, or is it hunting up and down teh revs?

i reckon air leak. not seated properly in the carb rubbers, or rubbers got a split.
treat the bike to new rubbers anyway, only around 7 quid each and makes removing / fitting the carbs a doddle.

While the bike is running, why don't you spray a little bit of carby cleaner around the carb rubbers, you'll be able to tell straight away. If there is an air leak, revs will rise further, and where the air leak is (you'll see if get sucked in).

Cheers lads.. Im going at it again today