the bike will turn over but only back fires after like 4 or 5 turns you think its out of time or what can you help

 

I would check the condition of the spark is it yellow or blue? if its a good hot blue then your ok there, next check\clean your carb make sure and clean those jets good, make sure to be observant of the rubber carb inlet to the top end, it needs a good seal (no cracks, breaks, or bad gaskets). if your carbs ok then check\adjust your valve clearance. Still no luck then do a compression test. It is a possibility that the time has jumped but from my experience this is pretty uncommon. the procedure i listed above usually can identify the problem. If I had to guess I would say probably your carb is the culprit, also make sure your running fresh gas that'll cause some head scratching sometimes. Hope this helps, lemme know if it doesn't and i'll go on from there!!