Being able to squeeze more speed out of a Honda CRF-100 dirt bike can make all the difference between leading the pack or being left in the dust. But finding this extra speed can be a challenge without making a few modifications to the dirt bike’s motor, fuel system and final drive. Some of these modifications are easy enough for most people to accomplish on their own in one afternoon. However, major power gains require extensive mechanical skill and a healthy wallet. Evaluate your expectations and make the right modifications to best suit your budget.
1) Replace the stock 14-tooth front sprocket with a smaller aftermarket 13-tooth sprocket. This will increase the motorcycle’s ability to accelerate quickly in any gear. Take note, however, that the overall top speed of the dirt bike will be decreased. Install a larger 16-tooth front sprocket to provide a higher top speed with a slight loss of outright acceleration.
2) Upgrade the motorcycle’s air intake, fuel and exhaust systems. Install a free-flowing air filter and exhaust system to replace the stock air filter and exhaust. Replacing the restrictive stock components allows a higher volume of air to pass into and out of the motor. Install larger jets in the motorcycle’s carburetor to increase fuel flow to match the increase in air flow. This mixture of fuel and air is then pulled into the motor and combusted, creating more power to drive the motorcycle forward faster.
3) Replace the motor’s top-end, consisting of the cylinder, piston, valves, camshafts and crankshaft, with a performance motor kit. These kits are designed primarily for racing and utilize camshafts that open the intake and exhaust valves for a longer duration, allowing more air and fuel to be pulled into the motor. Some kits can increase the motorcycle’s ability to rev higher than a stock motor, allowing the motor to generate power longer. Installing a performance motor kit requires removal and disassembly of the motor.
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