The car guys have been enjoying engine swaps for years. It?s the simplest and most reliable way to get extra horsepower?which is why we see RX7s tooling around with 6.2-liter GM V8s, and tiny Honda Civics with Acura power.
Motorcycles are another matter, though. It?s an engineering nightmare, and you obviously lose the stealth aspect, because the motor is on display. But that didn?t dissuade Cole Mishler, who has just built the ultimate pocket rocket: A Honda Grom with a lithium ion power pack and more torque than a Yamaha MT-09.

It shouldn?t work, but Cole is a designer for Zero Motorcycles, so he had a head start on the engineering front. And the resulting ?Grom Reaper? screams out to be turned into a kit for other owners of the Honda MSX125.
The first question: why" ?The stock Grom has a tiny frame and a low-performance engine,? Cole tells us. ?So I saw the potential to really showcase the power and quality of the Zero drivetrain.?

More realistically: ?This thing is a wheelie machine!?
The Grom Reaper has more than double the power of a stock Grom, with 27 hp rather than a humble ten. Torque goes up by a staggering +800%, from 8 to a heady 66 ft lbs. (That?s almost as much as a Harley-Davidson Sportster 1200.)

With only an eight-pound increase in weight, acceleration is insane. Fortunately, Grom Reaper is geared sensibly to avoid tank slappers.
There?s a moderate increase in top speed from 56 to 66 mph ?(106 kph), governed by an enormous 55-tooth rear sprock...