Buying Performance Parts For Your Bike
If you've ever looked through a parts catalog, then you
know that there's literally thousands of brightly colored after-market parts, with snappy names, claiming to give your bike INCREDIBLE POWER INCREASES! Now if you look at the price tags for these
items you’ll understand why the saying goes “you can make your bike as fast as you
want to spend.” Its also important to note
that the amount of increased power you can squeeze out of a bike is subject to
the “law of diminishing return.” That
is, if it costs $300 to get your first 20% increase in horsepower out of your
bike, it will likely cost around $10,000 to get the last 10%.
You’ve likely seen parts referred to as stage 1, 2, or 3. This is because engines should be modified
for performance in stages. By working
systematically through the stages, you’ll ensure that you’re getting the
biggest boom for your dollar.
Categories of Performance Parts
There are basically five systems that you are upgrading to
increase your bikes performance. They
are Intake/Fuel, Exhaust, Ignition, valve train, and displacement.
Intake
Intake is pretty straightforward; if you get more air into
the engine, it can make a bigger explosion.
Fuel is directly connected to this, as you must increase the amount of
fuel in proper proportion to the increase in air. (This is covered extensively in the previous
post Carbs 101) (Oh and if your bike is EFI you are going to hell)
Higher performance is here begins with a high flow air
filter, and ends with high flow heads.
Don’t get carried away with flash; my advice is to spend wisely and save
your money for more performance.
Note* velocity stacks don’t filter the air and are truly
meant for racing. Don’t run velocity
stacks unless you love cleaning your carburetor.
Exhaust
For many v-twin owners, the first modification is to swap
out those stock exhaust pipes for some stylish drag pipes. While this will make your bike heard for
miles, it does little to nothing to help performance. As far as performance goes, nothing can beat
a good 2into1 exhaust. I know it seems counterintuitive to cram more exhaust
into one pipe, but these systems allow the exhaust to work off of each other’s
momentum and create a broader power band.
Typically high-end sport bikes will come stock with a great exhaust
system, but that doesn’t mean that you can’t spend 2-3k for one or two more
ponies.
Ignition
Simply put, a more complete combustion will create more
power, and in order to get better combustion you’ll need more electricity at
the spark plugs. Upgrades begin with
higher performance plugs and wires. The next step is different depending on the
type of ignition your bike uses. A high
performance kit for a CDI unit, for example, will consist of high voltage coils
and pickup coil. Ignition kits are
common and affordable. Just make sure
you buy a reputable brand.
Valve Train
The valve train may use either a pushrod system, or overhead cams. Either
way the goal is the same. In order to
get more power, you need the valves to open wider and stay open longer. This requires swapping out for high
performance cams with more aggressively angled nodes. Lighter push rods, rocker arms, and valves
will help prevent you from floating valves when using these high performance cams.
Displacement
Upgrading an engines displacement seems like one of the most
intuitive upgrades. (If you want more
power, get a bigger engine) This,
however, is not always all its cracked up to be. First off this is one of the most expensive
and labor-intensive upgrades you can make.
Second, while upgrading to a larger size engine will make more power, it
may not change the power band in the areas you want.
So what should you do when?
Here’s a chart of performance stages that applies to most
bikes on the road.
Hopefully this helps you wade through the sea of performance
parts, and start spending your money more effectively.
