hi guys im looking for a little help sorting the 21 im doing up at the moment. it wasnt running when i got it so i had the carbs off, the left hand one was all gummed up, so i cleaned it up the best i could then put them back on, with a little mucking about it ran, but at tickover nothing but cold air comes out of the left pipe, with a little rev it chucks out loads of white smoke, more revs and it clears. but the revs take there time to come down again even if i snap the throttle shut. iv had it out on the road and it flys with3/4 to full throttle, but lower down it couldnt beat sleep. any help would be very very much appreciated. im hopeless unless iv got a manual in front of me. thanks in advance miff87