I have just bought a new set of plugs. I went ahead and got the iridium plugs even though I read someone said they wouldn't help carbed bikes. The post that ststed that a carbed bike couldn't retard for preignition makes sense. I think I will also check timing. I believe the bike was raced before I bought it. I bought in with a salvage title with only 4650 miles. So, I don't know the history of the bike and that is a little troublesome. I have put 20,000 miles since I got it and haven't changed plugs, yet. That may be the simplest explanation. I just dread pulling the damn thing all the way apart to change plugs. It's supposed to rain all night tonight and tomorrow. So, I have plenty of downtime. I'll post results Wednesday. Thanks for the help.