If your vehicle wants to continue to accelerate when it has reached maximum rpm as controlled by red line or the rev-limiter then reducing the number of teeth on the rear sprocket (increasing the gear ratio) will increase your top speed. If on the other hand your engine stops accelerating at some speed below the maximum speed for the motor then you my actually increase you speed by reducing the final gear ratio.
Alternately you can change the fuel mapping on the engine so it produces more power and can increase the rpm of the engine. Simply making the mixture richer will not do this. In general when producing maximum power you want to make the fuel mixture as lean as possible, but that is another challenge.
If you really want to increase the performance of your motorcycle or other vehicle you should get books on the subject or go to a local motorcycle shop to get some guidance that can be applied directly to your vehicle.
One thing to remember, maximizing power requires maximizing expenses. Speed is not cheap.
Niel Leon
Engineering.com
