The Motor

"I think it makes a few horsepower less than Honda's 300EX, but at 313 pounds versus 372, it may actually be just as fast if not faster than the 300EX," says our test rider Allen Knowles.

To power the Raptor 250, Yamaha borrowed the motor from their Tricker stunt motorcycle sold in Japan. Yamaha chose that motor for the machine due to its lightweight, simple and economical design. Some changes were made to the motor’s internals in its transition from two to four wheels mainly focusing on extracting more low-end torque. 

The 249cc four stroke motor features a single overhead two valve design. While the motor is air cooled it does feature an oil cooler to help with heat issues. The motor features a compression ratio of 9.5:1 and measure in with a 74 x 85mm bore and stroke. Those bore and stroke numbers are indicative of a motor that should rev well. Fuel is fed to the 250’s engine through a 29mm Mikuni BSR carburetor and starting is handled by a push button electric starter with no backup.

The Raptor 250 borrows its engine from a stunt motorcycle sold in Japan. With a bore and stroke of 74 millimeters by 58 millimeters, the little 250 is a quick revver. What's more, with its five speed manual-clutch and chain drive, the Raptor is a true sport machine.

The lower end of the motor features a 5 speed transmission without reverse.  The Honda 250EX features an auto clutch with a manual clutch override. Yamaha felt that younger riders looking to move up in their sport lineup would rather have the pure sport setup of a full manual clutch. Why no reverse? No reverse means less weight, less cost and most up and coming future racer heads will most likely be willing to push their light weight machine a bit to save a few bucks, like we did when we were 16.

An O ring chain handles the final drive duties. By using a chain drive instead of a drive shaft like those found on other popular Japanese models, Raptor owners have the ability to change their gearing should they switch to a different tire size. Also shaft drives put a lot more drag on a motor than chain drives do, so the Raptor is more efficient at transferring its power to the ground. Less power loss in the drive train equals harder acceleration and a higher top speed.

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