'99 cr250 starting then backfires and quits

[L.Vegas400]

exactly what it says. it is stock bore and has always run fine until lately. usually it does it about 2 times and on the 3rd time it starts and runs fine. the plug is cleaned between each kill and foul. it will start, smoke like a 2 stroke does, i rev it up to maybe clean out the residue, about 1.5 seconds go by and it starts to foul the plug, backfires with a small (5") shot of fire, and continues to die. the plug is just as wet as can be. there are no leaks in the exhaust, and the filter is clean. the carb has never been messed with, and it has gas. any ideas??

sounds like it may be getting a lil too much fuel while kicking it ...are ya holding throttle open some ?

[L.Vegas400]

nope. no throtle on start up. as soon as it fires it is reved to clean the gas out of the cyl.

[bongwater200]

You didn't, by any chance, leave a rag in the intake boot after your last air filter change? I've seen people have this problem and they swear up and down that they took the rag out, only to take the filter off and find a rag still in the boot!

^ i thought of that also ...;)
but he says it runs after this happens .... so now i dont know what to think ...except possible ground problem ...that is intermidant...or alot of gas is left in there from previous riding

[L.Vegas400]

hhmmmmm..... i shut the gas off, drained the carb, kicked it over several times with no plug and no gas. put the plug in, turned the gas on, and wala, she runs. the only thing i can think of is the oil settled and was pushed into the cylinder fouling the plug. after draing the old gas between the cyl and the jug and drying the cylinder,,, it runs. :ermm:

ohh and there was no backfiring this morning. and the gas was left on between the last ride and now.......

occasionally my 2 strokes have backfired ..also ..I always heard it was from alil xtra gas either in the pipe or cylinder ...