You ask we answer. Here's the latest in our "Ask a Mechanic" series.
Q: When should I repack the exhaust and does the inside of the pipe need cleaning?
A: I recommend repacking the exhaust, whether 2-stroke or 4-stroke, about every 50 hours. If you wait too long the exhaust sound turns an annoying high pitch and you'll experience a loss in horsepower. Repacking is pretty easy as you just need to drill out the end cap rivets to get at the old packing. Some end caps have a bolt which removes and reattaches making the process even easier.
Once you have discarded the old packing clean the inside of the exhaust with contact cleaner to remove the carbon build-up. (You might as well clean the outside too!) Once clean and dry add the fresh packing. Make sure it's a tight fit otherwise you won't get 50 hours out of the new packing. Big Gun makes a pre-rolled pack that slips inside your slip-on if you prefer that route but only for Big Gun exhausts. For a more detailed "How To" check out How To Repack Exhaust.