Diagnose my problem!!!

[CEET400ex]

PLEASE HELP!!!
Ok.I have a 1996 Yamaha YZ 80. Just got it bored and put new topend in last night(.20 over).-Wiseco.Went riding today.Well it ran fine but was smoking a lot(too much oil in premix).I let it set for about an hour then went back riding.Well it would go one speed and i had it pinned and it would still go that same speed.Then it dies and while its dying it makes sounds like puffs of air is coming out the exhaust.It also still has compression.What could my problem be.Thanks in advance.

[JUSTINcredible]

probley fouled a plug

[CEET400ex]

I thought it was a fouled plug too. But if i kick it like 20 times,it will start and die and spit air again.Could it still be a fouled plug if it will start every once in awhile?

[JUSTINcredible]

my blaster did the same thing when I mixed my gas to rich and the plug was fouled and i turned the idle speed all the ways down and it has worked ever since

[Chanman420q]

jetting?

[CHAUNCY]

I have a kx100 and I am almost positive it is a fouled plug. When I go riding I can get about 300 feet then it dies. I gotta change the plug and its fine for the rest of the day. I basically had the same problems as you too!