I'm about to buy a new jet to fix the 4 stroking guys. If there is anything you can tell me to keep me from wasting my money if it isn't the problem, what is it?
I have a piece of spring metal holding my needle in place at the leanest setting, and it works surprisingly well. I lost my clip, again, so I improvised.4 stroking is caused by an over rich fuel/air mixture. So if your exhaust is not the culprit then it is the jet. Can't remember what slot you have the needle clip in.
You can try running without the air filter on just to see what happens. Maybe the filter is full of oil or other crud?