Little else turns a dirt bike into an aging relic than a romped, reamed and dented exhaust pipe.
Bar banging, tree hitting and plain 'ole crashes can wreak havoc on just about every inch of the exhaust system. Minor dents usually pose little issue but any that make you wince need fixing or you'll lose power.
The casual trail rider can certainly get by without a repair but for anyone who races or just prefers a pretty bike removing the dent is essential. However, in the event where the dent closes off considerable air flow the impact to the bike's performance could be significant. Thus, riding a put-putting bike is no fun even if you're fooling around in the backyard.
The easiest method to fixing the dent is simply buying a new exhaust system. If the dent only affects the muffler than sliding on a new slip-on is your best bet. The same applies to the head pipe or the mid pipe on a 4-stroke though in our experience if any one of those is extensively damaged it's likely other components need replacing and you're back to replacing the whole exhaust, anyway. If your prone to denting your exhaust pipe try installing a guard.
The 2-stroke pipe is probably the easiest and cheapest fix by itself. But when including the silencer or you've got a banged up 4-stroke exhaust system, replacing the affected parts or the entire exhaust system might work best in your favor unless you're adept at welding and basic metal work. Replating or hiring someone to remove dents from several sections could prove nearly as expensive and is certainly more time consuming than ordering a replacement. Keep in mind, dented and repaired metal is generally weakened metal. So, if it's an old exhaust use this as an excuse to get that upgrade you've been eyeing!
Broken, beaten and scarred but probably not enough to warrant replacing
Unfortunately though, the replacement route tends to also be expensive. But if money is tight, maybe you've got a vintage pipe and restoration project in progress, or you'd rather not replace the exhaust system on a bike used primarily for messing around then you've got several options and a bit of work. Understand, fixing a dent yourself is not easy and without proper acumen poses significant hazards. So, before you do anything, remove the affected pipe. Don't use heat or flame while it's attached to the bike. This is a good way to start a fire or worse. Clean it, too.
The most common do-it-yourself method to dent repair is plugging both ends of the pipe with one end containing an opening that allows you to feed air using an air compressor. MotoSport sells no such contraptions nor can we recommend what to use. If you're this far into the process it's likely you've received some suggestions and recommendations. Heat the dent using oxyacetylene welding or oxy/propane torch. See, told you it wasn't a simple process. Once the metal is hot it's now flexible so pump in air which pushes the dent out. Don't expect perfection but it should make a large dent into a something more akin to normal wear and tear.
A bruised and battered 4-stroke head pipe
If the pipe you're trying to fix is made of aluminum, nickel, tin, titanium or any other non-ferrous metal you'll have less success or end up cracking the metal and you'll be back to square one. Another option you might hear when asking for advice is filling the pipe with water and freezing it. The expanding frozen water pushes on the weak dented metal thereby solving your problem. A far easier solution than torches and compressed air!
Yes, this method works, not always, but it takes a few tries and doesn't usually fully remove the dent. Remember though, what happens when water and metal get together? Rust. Additionally, the expanding water could also cause welded seams to split and you'll be back to square one.
So, if you've had a yard sale type of crash or had one too many run-ins with fellow riders or other obstacles, weigh the cost/time benefit to either replacing or fixing the dented pipe. A final option, if you're bent on keeping the existing pipe, is mailing it to a specialist in pipe repair who does it for a nominal fee. Several exist but factor in mailing costs and time off the bike if this route makes more sense.
Written By: AndrewT