Hello i have owned 2 5th gen vfrs both i got with high mileage from original owners with service record. i work in a auto repair shop and we have a product that we use to clean carbon build up. the product is called motorvac we have a machine that the product goes into but on my motorcycle i just run it through the gas tank 1 8oz bottle does 1/4 gallon so i usually wait until it has about a half gallon in the tank and add the detergent then let the bike run for about 45-60 min. it is a great product and on both of my vfrs with 90k + on them i noticed a big difference. the motor accelerates much smoother. i would recommend trying it for your self. :thumb:. Try typing in (MotorVAC: Fuel Detergent) in you search bar.