the best thing to do is check which cylinders its dropping when its hot by pulling the ht leads off one at a time.if its electrical like a coil or pick up then 1+4 and 2+3 run the same coil and pick up so try pulling a ht lead of each cylinder.use a pair of insulated grips or you will get a belt from it,when you can estblish what ht cap being removed makes no differene to the bad running then your half way to fixing it.for instance its running crappy and you pull no 1 ht cap of (left hand side)the bikes engines speed doesnt alter+this cyclinder isnt doing anything if it does alter like die completeley then it WAS running on that one and so on.
adam bike doctor
July 2010