You've pinched pennies, said "No" to evenings with friends and put in longer hours all for the sole reason of saving money to buy that prized new exhaust system for your dirt bike.
After you placed the order, delivery day turns into Christmas morning. You can't wait. You track the package progress hourly. Finally it arrives at your front door. You leave work early. It's that important.
It's a thing of beauty. The best $1000 ever spent. That night you're lost inside the garage affixing it to your ride. The after-photos prove breath taking. Texts, emails and phone calls dispatched to friends and riding buddies brag about this gem and ask who is riding on Saturday.
This weekend is going to rip.
Only it doesn't.
In fact, you experience so many problems you first blame the pipe and then wonder if the installation process went awry. Actually it is the pipe, sort of. Not that it's defective but the engine's current air fuel mixture configuration can't handle the power of this new dynamo.
When deciding to upgrade the exhaust on your dirt bike or ATV it's not as simple as buying whatever is the apple of your eye, installing it and tearing around the track or trail. That's actually the easy part. Upgrading the exhaust means re-jetting a carbureted bike or tuning a fuel injected bike in-line with the new exhaust system. Bottom line: You've got more parts to purchase and further time dialing in the new set-up.
If you know how to jet the carburetor you're in luck because you can do it in between Motos or rides after getting a feel of the bike's response to the new exhaust. You just need to determine whether the engine is running rich or lean. As you probably know, re-jetting is sometimes an "exhaustive" process unless you get it right the first time. If you've never jet a carburetor it's a time consuming process that includes:
- Draining the fuel from the carburetor
- Removing the carburetor
- Disassembling the carburetor
- Installing the new jet kit
- Putting it all back together and testing the jetting
Expect to do this again if you're even a little bit off. Yes, at about this point you're probably wishing you'd stuck with the old exhaust system or owned a 4-stroke.
Because tuning a 4-stroke is nowhere near as complex but still requires additional tools (more money) since the current setup, especially if it's stock, unlikely provides enough tuning differential to compensate for the new system. Therefore, grab an EFI tuner. It's a pretty straightforward plug-and-play device but if you run into trouble with the wiring or find reading instructions akin to learning a new language schedule a date with a trained mechanic. No need to disassemble anything - it's really as simple as the push of a button once you've installed the new controller.
Of course, you can fiddle with the air screw and adjust the idle all day long but don't expect much to come of it. Manufacturers typically do not equip the necessary sensors to compensate for the exhaust upgrade so grabbing the necessary fuel controller or jet kit adds several hundred more bucks to your total package.
Additionally, when adding a high performance exhaust system you'll tap into the full potential of the new pipe if you also upgrade the intake system. It's not a must-have but if you're investing in an expensive upgrade for the purpose of performance and power, it's advisable to upgrade the air filter at the same time. Twin Air, Loudmouth and No Toil offer superior products to compliment your new exhaust.
Upgrading these elements together provides maximum benefits offered by the exhaust and intake system, plus it requires re-jetting only once. Upgrading the exhaust or the intake system independently usually means re-jetting the fuel system twice. So why not do it together and be done with it? For more information on re-jetting read A Simple Guide To Jetting Your Carb.
Well, we're not done yet because there's more to consider before choosing your exhaust upgrade.
Where Do You Ride?
Most public trails enforce a decibel limit so if that throaty new exhaust system now equipped to your bike exceeds noise level requirements at an AMA sanctioned off-road race you're done for the day. Or if you're busting ear drums on public lands, expect park rangers to chase you down, impose a fine and end your weekend of riding.
Accordingly, riding on public lands usually necessitates a spark arrestor. If you ride strictly Moto you're in luck but if you're involved with hare scrambles or other off-road races, or trail riding with friends all summer on public lands, it's likely you'll need a spark arrestor. Just like the decibel level, if AMA regulations for an off-road race require a spark arrestor and you don't have one you'll post a big, fat DNS. Similarly, if you're riding a public trail system, expect a ranger to come after you like a robbery suspect on the loose to give you a fine and end your day.
Silencer - Muffler - Slip-On
Wouldn't you know it - that new exhaust system came with a silencer. Which is also called a muffler. Which is also called a slip-on (but mostly in the 4-stroke world when purchased separately from a complete exhaust system.) It's the part emitting the smoke. But for 2-strokes it's most often called a silencer so don't confuse a silencer as describing a muffler that's quieter than other mufflers giving you access to areas with restricted decibel levels.
Of course many exhaust systems allow for the removal and replacement of the silencer or muffler but now you've perhaps needlessly added another few hundred dollars to your exhaust upgrade investment plus the time involved for removal and replacement. And that tricked out new silencer now sits in your garage.
Even worse, perhaps you bought an exhaust system with no option to replace the silencer or muffler like this Bill's Pipes 2-Stroke Pipe & Silencer Combo for 2-strokes and this Bill's Pipes RE 13 Complete Exhaust for 4-strokes. You've just ridden yourself into a corner.
Keep in mind that it's possible to reduce sound levels by repacking the exhaust. However, if you're reaching into high decibel levels with a new system, repacking a fresh silencer probably won't help.
Spark arrestors usually sell separately unless pre-installed. Motocross and Supercross events generally don't require a spark arrestor therefore it's easy and most common to purchase a complete exhaust system without one. Most spark arrestors say so in the product name anyway. Riders get into trouble when taking a day off from the track to spend an afternoon on trails where the spark arrestor requirement is enforced.
Adding an aftermarket spark arrestor requires replacing the slip-on or silencer. The other option involves including an end cap that meets United States Forest Service (USFS) specifications to the existing slip-on or silencer. But, these end caps usually have little to no effect on decibel levels. And, like the previous Bill's Pipes examples, some systems leave no option for easy solutions other than to replace the whole thing.
Riding areas or racing events requiring a spark arrestor almost always enforce sound limits so manufacturers often incorporate lower emitting decibels with their spark arrestors but not necessarily the other way around. Examples include the FMF Q Stealth Spark Arrestor Silencer and FMF Q Stealth Silencer for 2-Strokes.
Mechanic's Note: Most OEM dirt bike exhaust systems off the show room floor do not include a spark arrestor and likely will not pass a sound check as they are mainly developed for closed course uses by the manufacturer
Research, Research, Research
By now you might feel a bit dismayed about buying that new exhaust. Like any purchase, especially a big, shiny expensive one, do your research first. The total cost for a complete exhaust system upgrade normally goes above and beyond just the initial price. Limit the overall financial hit and prevent buyer's remorse by choosing correctly and grabbing an exhaust system that not only meets your riding needs but addresses local riding requirements or wherever you ride most.
For additional exhaust related information check out:
- How to Pick the Best 4-Stroke Exhaust for Your Dirt Bike
- How to Pick the Best 2-Stroke Exhaust for Your Dirt Bike
Written By: AndrewT