1973 yamaha dt360 spark problem

I had a 1973 AT3, those bikes had a pretty sophisticated electrical system, including an alternator and electric start(which actually just reversed current to the alternator).

Anyway, I'd start at the plug and make sure it's the right one, and then work your way back upstream. My 125 used a B8ES, not sure about the bigger bike.

Is it still using the oil injection or has it been converted to pre-mix? Could be fouling the plug, what does it look like when you pull it out?

it still does have the oil injection. the plug looks fine.

Have you tried holding the base of the plug against the motor and kicking it to see if it indeed has spark? Make sure you hold it by the rubber and don't contact any of the metal on the bike.

ive tried that it has no spark at the plug