hello everyone,I will try to be clear (my english is not so good). 
I have a brand new pre jetted mikuni vm26,needle clip is in 2nd position,new ignition stator(wich comes from a 175 lobito,I believe they are the same but is it ok?)  2.4mm advance timing.new piston rings ( stock bore). 
The bike doesnt run fine and has no power in low rpm in the first 1/4 of throttle.(a bit like a motocross).idle seems to be good,bike starts good 2nd or 1st kick. 
I would like to know what are the measurements/size of the intake manifold for a 199 (cylinder side not carb side),and what could be the cause of a bad reving. 
Thanks a lot for your answer.