I did not mean change the timing.
I meant to say, make sure your timing is good and your spark is proper.
I had a phbg doing the same thing and i couldnt figure out why, i had great spark, my jetting was spot on( after i ported like crazy) it just ran like shit and i couldnt figure it out..
First i changed my exhaust because with the porting the bullet just couldnt do what i ported for. Changed to a proma and bla dow! porting and exhaust and clutch has to all work together.
you have any more exhaust to t4y out>?
anything lower than a 45 just seems too small with a ported and case matched e50. your mixture screw is sensitive, you gotta do it like a 1/8 turn at a atime.
also your condenser might be worn out.