Cruel but true: The most cost-effective way to increase the power of the Honda CRF250R is to
sell it and get a different 250. There, we said it, but it
brought us no joy. The truth is, we love the Honda, but
it’s at least 5 horsepower down on most of the bikes
in its class. That’s a lot to make up for with handling
We like the Honda so much, though, that we
couldn’t stand to leave it like that. It’s still the lightest
250 four-stroke (or at least tied for that honor with the
Yamaha and the KTM Factory Edition.) It still handles
like a feather and has awesome suspension. We
decided to invest time and money to see if we could
close the motor gap. We’re like mules in a sense—way
too stubborn or too stupid to take the easy road.
PATHS TO POWER
There are only a few ways to increase the output
of a modern 250 four-stroke motor—and all are
fraught with peril. You can make it a big bore.
Another word for that is cheating. And, increased
displacement isn’t the be-all, end-all solution, as you
often have to deal with hard-starting and a lower rev
ceiling. You can also make it a full-on race motor,
but that requires a diet of expensive race fuel and
We decided to go a more conservative route and
give the Honda a moderate increase in compression,
a remapped ignition, a different cam and a new pipe.
Here’s the stuff we settled on.
• High-compression Vertex piston ($212). This
pumps up the compression ratio to 14.6:1, which is
almost a full point over stock. That means we could
still run pump gas.
• Hot Cams Stage 2 cam ($215). The nice thing
about a Honda is that there’s only one cam to
replace. The Stage 2 is more of a mid-to-top cam
• FMF Factory 4.1 RCT Ti exhaust system with a Ti
MegaBomb header pipe ($974).
• Vortex ECU with Rocket mapping ($1050). This is
the most misunderstood modification. We’ve learned
that you can’t expect the stock ignition to work
optimally with a modified motor. Conversely, you
can’t just bolt on an aftermarket ignition and expect
it to have the perfect curve for your combination of
compression, exhaust, fuel and conditions. We’ve
seen great results, on the other hand, when you
have a map custom-made for a specific engine
configuration. That’s why getting a programmable
Vortex ECU is only half the battle. You can get so
much more with a custom map, but it’s not easy to
do all the testing yourself. Josh Pits at Rocket Engine
has spent enough time on the dyno to figure out the
best curve as a starting point. Chances are that it’s a
good finishing point too.