I thought for sure that my Polaris 400 needed a rebuild. The bike just wasn't revving out like it used to. It idled fine, but just didn't have the power. At first, I replaced the spark plug and cleaned the air filter. No better. Then I thought it was the carb. But it ran ok, just no power. Then I remembered a post from this board from a long while ago. The guy said that his exhaust was clogged with mud. Well, I checked my exhaust and sure enough, it was clogged. I always clean off the bike, but never thought to clean up inside the exhaust. Now it has more power than it has in a long while. Guess its been clogged for quite some time! I just like to say thanks to whoever posted that tip. It saved me from unneccesarily tearing into my top end!

How exactly did you clean your exhaust?

Mud inside the exhaust?????????
It shouldn't be able to come in, no?

I just discovered the same thing about my Rubicon. I am now looking into snorkeling the exhaust. It was packed with mud!

Im the one to take the fame for this one.It was me who mentioned the exaust pluging up on my Xplorer about 2 months ago.I did everything,than one day I seen the downspout tube to my exaust pluged.I cleaned it and that took care of ALL my performance problems,ranging from spark knock,poor accelleration,the engine ran extremly rich,and it just had no balls,
Bill

Thanks Bill. I would have never thought to check the exhaust.