do the contact breakers spark with the engine running? if so either the condensor is not earthed properly or is faulty. if there is no sparking, then i would suggest
a) timing check
b)a carbs strip down and thorough clean with ultrasonic tank
drewps
good de-grease and just "key" the paint with wet and dry. I would recommend PJ1 yamaha silver bit its not being manufatured anymore. I just tried yambits case paint which is crap and spoiled my new cases.
try and get the PJ1 NOS.its petrol and oil resistant when cured!!
drewps