There are many ways to changing a bikes power character. Certainly a different silencer, fuel injection firmware or camshaft profile will affect power delivery. But there are simple and very effective ways of adjusting an engines’ power character without directly altering the engine.
Every bike has a unique power character, which is the nature of how the engine develops power. Some bikes, like a ported RD-350 two-stroke, needs to be rev’ed high to make horsepower. Once its’ on the pipe, watch out! Big interstate tourers make copious amounts of smooth power, developing huge torque off-idle like an electric motor. Knowing this, motorcyclists frequently want to move their bikes’ power band to suit the kind of riding they do.
If you are fortunate enough to be riding a bike with a chain drive, you can quickly tailor the bikes’ power character by changing the final drive ratio. Simply removing or adding a tooth on the countershaft sprocket will have a noticeable effect upon power delivery. Removing a tooth makes for better hill climbing; adding a tooth makes for less vibration and better fuel mileage.
As an inexpensive and quick mod, off-road riders can keep multiple countershaft sprockets on hand for changes. Really serious guys will swap sprockets mid-ride. My Italian Husqvarna’s countershaft sprocket was held on with a circlip, once the rear wheel adjusters were backed-off, was quick to swap. I did carry an extra circlip should the original get damaged or flung into the weeds. Companies like Renthal or JT Sprockets offer several configurations of countershaft sprockets with varying numbers of teeth.
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