OFF-ROAD HOT ROD
With the additional power, they dropped the gearing
from 13/50 to 13/48 or 49. After chewing through the stock
sprocket and chain, BDSB fit on a stainless steel Ironman
sprocket and a Regina Z-ring chain.
The extra power will produce a bit more heat as well. To
combat this, an override fan switch is used so you can turn
on the fan when you get into the tighter singletrack. The
stock thermostat actually keeps the machine in a good
temperature range where it makes consistent power, so you
don’t want to eliminate it. With the override switch, though,
you don’t need to wait for the engine to hit 212 degrees for
the fan to automatically come on. You can use any handle-bar-mounted switch and just break into the fan wires before
they get to the fan.
The BDSB Dead-end handlebar weights work to get rid of
the vibes that put your hands to sleep and contribute to arm
pump. They also fit with the Cycra Pro Bend full-wrap hand-
guards, which do a smart job of protecting the woppies.
The new, larger, 3-gallon Acerbis tank gives you a little
more than a half-gallon more fuel and actually comes with
all the new fittings and hardware you need to mount it up.
This is a huge bonus, since some tanks don’t, leaving you
trying to figure out what hardware you need to fit the fuel
pump in place. It’s perfectly thin and ergonomically sound.
Finally, the suspension is lowered 2 inches in the rear
and 1 inch up front to make the bike much more comfortable for people with inseams of 31 inches or less. The idea
of 1 inch shorter in the rear versus the front really balances
out the rear-end-high riding bike for a more stable platform
at speed. For the guys who are tiptoeing on these bikes,
the slightly shorter platform really helps inspire confidence
in all situations other than huge whoops. They will notice
increased confidence in cornering and in slower, rocky situations. MotoLabDirtBikes.com did all the suspension work
here. On this bike, they also increased the spring rate in
the front to a . 48 and changed the base valving. This kept
the shorter bike riding up in the stroke, which actually helps
keep it plusher. Also, the base valving was softened a bit
for a plusher feeling in the sharp edges found in singletrack
IS THIS A PIPE DREAM OR A DREAM
It’s interesting that anyone would go searching for more
power on a 510cc machine, but Dave and the Best Dual
Sport Bikes clan are constantly evaluating power traits.
We really like his bottom-power kit. It’s cost-effective and
works for a serious trail rider. The throttle-body swap is
pretty high end and targets a rider who wants big juice from
mid to top. It’s a whopping chunk of newfound power and
can elevate the trail power of the 450/500XC-W to that of a
true racer. But, it’s not an easy mod, and only the serious
should apply. ❏
www.bestdualsportbikes.com— Big Bottom kit, Power
Quiet end cap, TPS tester, Dead End bar ends, High
capacity oil cover, Ironman sprocket and Regina chain
www.acerbis.com— Gas tank
The 42mm Keihin throttle body has top-mounted injectors
and can benefit from fine-tuning. BDSB offers a TPS tester,
which allows you to properly check and tune the system.
It may look docile and meek, but the modded 500XC-W is a
real terror on the trail. It makes strong and massive power
just about everywhere in the range. Is it overkill? Probably,
but boy is it fun.
This is the 44mm Keihin throttle body off of the 450SX-F with
the bottom-mounted injectors. It makes for a huge power
gain, but you have to get it from KTM.