Driving too slowly. A clutch starts to engage around 2,000 rpm and will lock up around 2,600 rpm. Driving at full throttle gives the clutch a chance to cool down. Full throttle locks the shoes in the clutch against the drum. When the clutch is not locked up, the shoes slip against the drum causing tremendous heat which dries up the lubrication in the oil impregnated bushing. The tremendous amount of heat generated can also anneal the spring which is the heart of the clutch. If the shoes turn purple from excessive heat more than likely the clutch is ruined and the spring no longer has the ability to pull back the shoes at idle.
Short stop and go driving. The longer you drive at full throttle the better off it is for the clutch, because it gives it a chance to cool off before the next engagement.
Driving with the foot on the brake. This is a problem with new drivers that are unsure of themselves. When riding a go-kart for the first time, try to find an open area that has no obstacles that you have to maneuver around until you get use to the brake and gas pedals. The driver must first be able to build up his or her confidence on the kart before putting obstacles in their path. A small back yard is not a good place to learn to drive a go-kart. In my opinion, a minimum of ¾ of an acre is the yard needed for a go kart. Teach your child to drive with one foot on the pedal—be it the brake or the gas but not to press on both pedals at the same time. You either want to go or to stop but you cannot do them both at the same time.
Changing the size of the tires. Putting on tires that are larger than what came with the kart will result in clutch problems. Tires exceeding 13″ in diameter stress out a clutch if the kart is not properly geared for the larger tires. If you are driving on smooth flat terrain than you may be able to get by with 14″ tires but once you get on hilly terrain, deep grass, then you are putting additional strain on the clutch, which will cause premature wear. Big tires look neat on a go-kart but you create your own problem changing to a bigger tire when the clutch isn’t designed to handle them.
Weight. A centrifugal clutch is designed to be able to move a certain amount of weight. Once the weight limit is exceeded, then the life of the clutch will be shortened. A good rule of thumb is the kart and driver (and passenger when it is a two seat kart) should not exceed 400 pounds. The kart weighs around 150 pounds add to this the driver (and passenger weight, if it is a two seater kart). If you know ahead of time that you will exceed the 400 pounds then buy a torque converter go-kart and avoid the problems of burning up the clutch asking it to do more than it was designed for.
Gear ratio. The sprocket on the engine and the one on the rear axle should have a ratio close to 1:6. This means for every tooth on the clutch there are six teeth on the rear sprocket. So if you count 10 teeth on the clutch there should be 60 teeth on the rear sprocket. (12 teeth on the clutch means a 72 teeth rear sprocket). A torque converter has a variable speed system between the driver and the driven pulleys so it can improve upon this ratio, which gives the torque converter an advantage over a straight clutch system. It improves the ratio by approximately 3:1 and can turn larger tires and drive at slower speeds without doing any damage to the clutch system. A torque converter is a more expensive system initially but it will last longer and is more trouble free when maintained.
Restrictions. Don’t try and reduce a go-kart speed by limiting the travel of the gas pedal or by putting a restrictor in the carburetor to limit full rpm. Either of these methods will result in the clutch slipping, which is self-destructive. A clutch needs full rpm to lock up as quickly as possible to be able to start to cool down. To slow down a go-kart you would need to purchase a gear reduction unit, which is like training wheels on a go-kart until the driver gets use to how the go-kart handles. A gear reduction unit can reduce the speed of the go-kart in half.