DOUG’S YAMAHA YZ100
To race a YZ100 you need to ignore the brakes and stir the gearbox for all it’s worth. Downshifting slows the bike down, while
upshifting and a locked right wrist make it go forward. The worst thing a 100cc rider can do is lose momentum.
The engine has a Wiseco piston, 34mm Keihin PWK carb, REM-coated gearbox,
Barnett clutch and Moto Tassinari reeds. That’s cheap by four-stroke standards.
Back in the day, the racetracks
were filled with 100cc bikes, with
everything from Novice to Pro
classes. And, here’s a little motocross trivia: Lance Moorewood made
history when he won the 100 Pros,
125 Pros, 250 Pros and 500 Pros at
Escape Country on the same day on
four different brands of bikes.
Today, the last bastion of 100cc
motocross bikes is the Marty Tripes
100cc Works Revenge Series. It has
simple rules. The engine must be
100cc (bored no more than two-over).
No water cooling is allowed, and the
frame must be from 1983 or earlier,
but you can make your own frame
or modify a stocker. Other than that,
it’s no holds barred.
The MXA gang has a long
history with 100cc motocross bikes,
but not in the last three decades,
so we tracked down Doug Dubach
for the opportunity to ride his very
special, carbon fiber 1983 Yamaha
YZ100. You can look at it, but you
really need to hear it at full song to
appreciate it. ❏