I have been replacing the old air filter with K&N filters this summer. I tried to go from 115 jets up to 120. K&N recommended a 10% to 12% increase in jet size. this would be more like 125 to 130 jet. The 120 was not nearly enough gas. I drilled the 115´s out to 1/16 inch and the CSR 750 runs great except for a hesitation when throttle first turned from idle.I am ordering 130 jets and are going to try them. will let you know what happens.