sucking back through the carb?

[mineralgrey01gt]

Ok, im tired of my 400 doing this lol so its time to figure this out. When i let it idle sometimes it will suck back through the carb. It also smokes when I ride it sometimes, not all the time and it smokes when i first crank it. is this thing out of timing? I wouldnt think its the carb doing this it just sounds like its out of timing to me

[01exrider87]

Does it only happen when you first start it to warm up? It used to happen to me on start up and i took the carb apart, cleaned it up real good and have yet to have it happen again.

[mineralgrey01gt]

it does it then and sometimes when i ride it for a while. Also it will stop smoking, then all of a sudden start smoking again after i ride for a while. It does not idle at all, the side cover is missing off the carb and i think its letting trash get into the carb way too easy. Also i was told that it might have a blown headgasket, i have yet to rip down the top end to see. I have another head gasket so i might just do it and put a new one in just to be on the safe side. Also when it smokes bad when i first crank it, smoke pours from the motor. I thought it was just the exhaust leaking from the head but i just tightened all that up really good and it shouldnt leak, so that kinda leads me to a blown headgasket possibly

[mineralgrey01gt]

also ill add this. When i do get it to idle itll idle, then almost die out, then rev then idle normal a little while then rev again. Im actually starting to think its the carb needing to be replaced on it the more i talk about this. It also has a bad miss to it when idling, sounds like its cammed hard but i was told its all stock top end minus a high compression piston (didnt know what size)

[mineralgrey01gt]

anyone?