Quick update,

still not sorted it out yet, removed airbox completely today and it revved out cleanly as if the airbox is a big restriction. Took reedblock off and checked reeds which were all perfect too. I checked the exhaust and this is not a cause of the problem for definite.

I also tried running the bike without airfilter in place and still wouldnt quite rev out.

Any help would be appreciated! I cant do much more in terms of airflow so Im stuck at what to do. Perhaps a smaller main jet? although as stated above the jetting is already standard.

Thanks very much

Hi Betarob

have you actually tried adjusting the carb fuel screw (assume its a dellorto) ? It can make a lot of difference to the way the engine runs, If removing the air filter helps then its probably just compensating for the fact that its getting too much fuel..

Also have you removed the choke plunger to check that it is shutting off the enriching circuit when you turn it off.

Try it with a new plug..

TLTEL