What would cause you to not be able to get the timing all the way to the timing mark. I put in a standard pamco. Installed the coil an everything that came with it.When I try to time it I cant get it to go all the way to the timing mark before it goes as far as you can turn the pamco.It will start runs like crap pops threw right exsuat an sometimes backfires threw left carb.Which I have cleaned the carbs.Now im lost an would love some ideals.Riding season here, an here I sit.All also put new brushs in.1977D basily stock besides exhaust now pamco.