These same mods work with the Coleman AT125-UT and AT125-EX models. All we did to this unit was the 12 tooth front and 50 tooth rear sprocket. Stock it has a 14 tooth front and 45 tooth rear. It made enough difference that even a small adult can turn the tires over now.
Changing and tuning with a better carburetor would help more. Always use High Octane Ethanol Free Fuel and Motorcycle Grade Oil.
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