"I've heard of two ways. <br>1. The most common i think is to burn it out with an asetaline torch. I think you take the exhaust all apart first. Then you burn everything from the inside untill it's red hot. Then all the carbon deposits should fall out when you tap it a little. I don't know what this process does to chrome though. It may damage it.<br> <br>2. In my moped manual, It just says to use a type of round metal brush to pull through the exhaust. Also use a metal brush to scrape off the inner pieces. <p>I'd try the second process. If that doesn't work, you can take your bike to a cycle shop or lawn mower shop and ask them to burn out the exhaust if you don't want to do it."