What is the reason why the scooter cannot go beyond 60 mph?
3 Answers
It may be due to issues with the electronically controlled choke and vacuum diaphragm of the carburetor, or the negative pressure fuel tank switch being damaged, causing fuel to flow from the suction pipe and resulting in an overly rich air-fuel mixture. Here is some relevant information: Types of motorcycles: Fuel-powered scooters belong to the motorcycle category. Those with an engine displacement below 50CC are classified as light motorcycles, while those above 50CC are classified as regular motorcycles. License plate differences: Regardless of the type, corresponding license plates and driving licenses are required for legal road use. Light motorcycles have blue license plates and require an F-class or higher driving license; regular motorcycles have yellow license plates and require an E-class or higher driving license.
I've been repairing scooters for over a decade. The most common reason for not reaching 60 km/h is aging transmission systems. A stretched, slipping belt is like running in shoes two sizes too big, while worn variator rollers keep the transmission stuck in low gear. Just this week, I helped a customer by replacing their belt with a Taiwanese-made reinforced one and upgrading to 15-gram heavier rollers - the scooter immediately hit 85 km/h. If the clutch shoe springs are loose, they can't grip the clutch bell properly, causing howling noises during hard acceleration. Check your belt width yourself - new ones are 20mm wide, and should be replaced when worn down to 17mm.
Last time my Jog was also stuck at 60 km/h. When I opened the air filter box, I was shocked—the filter element was completely clogged with willow catkins, turning into a felt cake! At high RPMs, the air intake couldn't keep up, causing the fuel mixture to become too rich and resulting in power loss. After cleaning it with a high-pressure air gun, it immediately restored to 70 km/h. Now I make sure to replace the filter element every 2,000 km. I also cleaned the throttle body—the backside had oil sludge so thick you could write on it. For carbureted bikes, you need to adjust the needle height; for fuel-injected models, you have to check the throttle opening data. If you don't have the equipment, it's best to visit a workshop to read the fault codes.
