Why don't you just add some weight to your flywheel( very inexpensive), or possibly put a oversize piston in it, change port timing, a bottom/ torque pipe, a power now (more torque/ smother transition) either mod will help significantly or all would be even better. a fraction of the cost of another used bike.- just my two cents- you could possibly adjust your power valve to some degree for smother power. A sprocket is really cheap and gearing it up will definately decrease the hit.