300EX Wont Idle Backfires

[thyman17]

I just got my 300EX running again and it wont idle. To start u have to give it gas and then it will start but it cracks and bangs and will only run wide open, whats wrong? is it carb or exhaust or what im stumped ????????????

[chargercalvin]

i guess you have put fresh gas in it and changed or cleaned your plug and airfilter. exhaust leak is possible but is probably your carb. take it off and clean it real good with some carb/choke cleaner. check your floats and your jets and whatnot. sometimes crap just gets in your carb. im sure you know all of this but sometimes a good cleaning will fix it....

[thyman17]

Well I found out what was wrong with it. The spark plug had no gap so it wouldnt run at all. Now it runs great.

[chargercalvin]

oh good. well that will do it

[Trxman300]

i had the same problem last winter. turns out that i have a complete 1/4 inch layer of green **** in my carb. i cleened it, blew out the jets and it runs like a beast.