1. ENGINE. The RM-Z250’s engine
is the slowest on the showroom floors.
It is down on every part of the
horsepower curve compared to its
competition. It’s actually worse than
it sounds. The RM-Z250 is 6 peak
horsepower below the two Austrian
bikes in stock trim. Our first mission
with our RM-Z250 was to pump up
the power without breaking the bank.
We gave the engine to Dasa Racing.
Dasa Racing’s goal was to make more
peak power and allow the engine to
rev out longer to pull the following
gear better. Dasa did some head
work, degree’d the cams and put a
JE high-compression piston in. To
keep the project under budget, Dasa
remapped the stock ignition. The
power became much broader on top
and revved to the moon, but it lost
any excitement it had. It would work
great on the Bonneville salt flats, but
not a motocross track. Dasa had the
engine know-how but was lacking the
expertise on the mapping.
2. MAPPING. We consulted with
Jamie Ellis, who is a mapping guru.
He told us the best thing to do was to
buy a GET or Vortex ignition for the
bike. It would make a huge difference
in the RM-Z’s potential, but neither
of those black boxes are cheap, and
we didn’t want to throw good money
after bad. Instead, we had Jamie
remap the stock ignition for both fuel
mixture and ignition timing. What a
huge difference. The bike went from