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By Mike Batchelor
How to select an exhaust system for your
ATV
 Let’s
face it, there is no such thing as too much money or too much horsepower
and when it comes to ATVs, the quickest and easiest way to add power is
to upgrade the exhaust system. ATV manufacturers are now building incredibly
powerful ATVs, but when it comes to the exhaust system, many manufacturers
tend to be rather conservative, thereby robbing our shiny new quads of
their true potential.
Aftermarket manufacturers offer dozens of fantastic and not so fantastic
solutions to pick up where the manufacturer left off. We wanted to learn
how to select an appropriate exhaust system so we sought one of the foremost
authorities on ATV exhaust systems, and put a call into Kevin Berger,
President of SuperTrapp Industries. An engineer by trade, Kevin has likely
forgotten more about exhaust systems, and how they can positively (or
negatively) affect an engines performance, then we will ever know.
Objectives
Kevin told us that the first thing you should do when selecting an exhaust
system is identify their objectives. There are a several reasons to upgrade
a stock exhaust system and each comes with certain tradeoffs. These objectives
fall into one or  more
of the following categories:
- Additional power
- Modification of stock exhaust volume or note
- Appearance
- Replacement of a damaged factory exhaust
- Reduced weight
Once you haveidentified their objectives, the next thing to do is find
exhaust systems that satisfy them. There are dozens of exhaust system
manufacturers and many of them offer multiple product lines to solve specific
problems. Some are designed to reduce noise (often at the cost of power),
others are purely cosmetic, and others are all about maximizing power.
You may, however, have more than one use for your ATV. Let’s say,
for instance, you use your ATV to hunt one weekend and the very next you
find yourself carving razorbacks at the dunes. During the rider’s
hunting expedition the goal will be to keep the ATV as quiet as possible.
Conversely, while ripping through the dunes, you will want to squeeze
as much power from your ATV as possible. A situation like this leaves
you with two options. Select an exhaust system that comprimises power
and silence or select a tunable exhaust system from a manufacturer like
SuperTrapp. A tunable  exhaust
system uses removable disks to vary the amount of backpressure. To reduce
backpressure just add more disks.
In any case be mindful of volume. As civilization continues to encroach
on our favorite riding areas, many of these riding areas are enforcing
maximum volume limitations. These riding areas often limit maximum volume
to 96 dB, so know the rules at any area you may wish to ride before you
select your exhaust system.
When considering volume, Kevin from SuperTrapp offers a word of
caution. Don’t assume that more noise equals more power. A
poorly designed muffler will introduce turbulence in the exhaust
flow which will actually impede airflow and reduce horsepower despite
the fact that it has reduced backpressure.
It is also important to remember that too little back pressure
can damage your engine. As backpressure is reduced your fuel/air
mixture is leaned out which causes your engine to run hotter. The
additional heat can damage your exhaust valves. Some people go to
a drag race and see dragsters with straight pipes and assume that
they should do it to their machines to maximize power. What they
don’t consider is that the dragsters engine will probably
be totally rebuilt when it has less than 10 miles on it so the mechanics
don’t really care about long term durability. Since you are
probably not going to rebuild your engine every 10 miles make sure
you consider long term durability when you select your exhaust system.
Quality
Once you have nailed down your objectives and hopefully
your choices, you need to consider quality.
The first thing you want to look at is material. Resistance to corrosion
is a very important quality in an ATV exhaust system. Your muffler is
very likely to be sand blasted, caked with mud and soaked in water; all
of which reduce the longevity of any exhaust system. If you work with
your ATV, you may introduce it to even more corrosive materials such as
fertilizer or insecticides. many aftermarket mufflers are made of aluminum
which is lightweight and somewhat resistant to corrosion. Some, however,
are made of stainless steel which is a bit heaver and more expensive,
but significantly more resistant to corrosion. The finish of a high quality
muffler should be brushed or polished, which will maximize resistance
to corrosion.
Another thing to consider is build quality. The finest materials
in the world are worthless if they are tacked together with bailing
wire and chewing gum. Some exhaust systems are constructed to hold
their innards together with rivets and spot welds, which isn’t
the best combination for a high-vibration, high-pressure component.
Look for a fully welded exhaust system, which trades rivets for
bolts in the areas that are meant to be used as attachment points
or in areas where welding doesn’t work.
Other Items to Consider
Spark Arrestors - Make sure that the exhaust system you choose
includes a USDA Division of Forestry approved spark  arrestor.
Spark arrestors help prevent fires by keeping superheated materials from
unexpectedly exiting your exhaust system.
Carburetor Jets – When you alter the amount
of backpressure provided by your exhaust system you may need to
re-jet your carburetor to compensate. Make sure that the company
you purchase your exhaust system from is willing to offer guidance
on this because the jet size you need to select will vary significantly
based on a number of factors including your ATV, the exhaust system
you select and you altitude.
Don’t Skimp - Select a system from a reputable
manufacturer that’s willing to invest in research and development.
Any company can bend pipe into an approximate shape, slap a muffler
on the end of it and call it an exhaust system, but a quality exhaust
system is designed by engineers that ensure their product will actually
improve the performance of your ATV. SuperTrapp for example, dyno
tests every installation of every exhaust system they design, and
will not release it to the market if it doesn’t meet strict
criteria.
An upgrade to your exhaust system is a simple, fast and cost effective
way to improve ATV performance. They can usually be installed in a couple
of hours with common hand tools, and in most cases a well designed system
can net a 10% improvement in power. They aren’t cheap, however.
A quality exhaust system will cost at least a couple of hundred dollars
so you want to make sure you have clear objectives and reasonable expectations
when selecting your exhaust system.
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