1. Install a performance exhaust system. This is one of the most effective ways to improve the performance of your 125cc. A performance exhaust system will allow your bike to breathe more easily and make more power.
2. Increase the air intake. This can be done by installing a larger air filter or by removing the air box lid. Increased air intake will help your bike burn more fuel and make more power.
3. Adjust the carburetor. If your bike is carbureted, you can adjust the carburetor to make it run richer. A richer fuel mixture will help your bike make more power.
4. Install a performance camshaft. A performance camshaft will change the timing of your bike's valves. This can help your bike make more power at higher RPMs.
5. Lighten the bike. Removing unnecessary weight from your bike can help it accelerate more quickly.
6. Install better tires. Good quality tires will provide better traction and allow your bike to accelerate more efficiently.
7. Improve your riding technique. The way you ride your bike can also have a big impact on its performance. By learning how to ride more efficiently, you can make the most of the power your bike makes.
