Asking a question for my buddy. Problem started last time we were out. When running the bike it starts to studder and backfire then will die. Also when you start it up and give it alittle gas when your parked it misses and backfires pretty bad. At first we thought it was bad fuel so we drained the tank and put fresh gas in. That didn't help. He is going to get a new plug today and try that. But the plug did look fine when we pulled it (even though it is the original).

Anybody have any other clue what the problem would be if the plug doesn't fix it?

Thanks

Russ