How do I know if my 150cc GY6 is a long or short case? I want to change my belt and it has no indication on it?
With a few exceptions, the 125/150 GY6 has two belt sizes: 743 for the short case, and 842 for the long. If you have a 10 inch rim on the rear with a tire that is 3.50 wide or less, it’s a short case. The belt cover will also measure 16 inches from end to end. If you have a 10″ rim with a 4.00 wide, or a 12 or 13″ rim, you have a long case. The belt cover will measure 17 1/8″ long. Another easy way to tell is simply to count the number of retaining bolts for the belt cover, the short case has 8, the long one has 10.
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