Scooter Drive Belt Size Chart
Quick answer: scooter CVT belt markings usually describe length, width, and belt angle. A belt marked 669-18-30 is about 669 mm long, 18 mm wide, and has a 30-degree side angle. Always compare the full belt number on the old belt before ordering.
Common Scooter Drive Belt Size Chart
| Belt marking | Approx. length | Approx. width | Common scooter use |
|---|---|---|---|
| 669-18-30 | 669 mm | 18 mm | Many 50cc GY6/QMB139 scooters |
| 729-17.7-30 | 729 mm | 17.7 mm | Some long-case 50cc scooters |
| 743-20-30 | 743 mm | 20 mm | Some 125cc/150cc small-frame scooters |
| 788-17-28 | 788 mm | 17 mm | Some 125cc/150cc applications |
| 835-20-30 | 835 mm | 20 mm | Common GY6 125cc/150cc range |
| 842-20-30 | 842 mm | 20 mm | Longer GY6 150cc applications |
How To Read A Scooter Belt Number
- The first number is the approximate belt length in millimeters.
- The second number is belt width in millimeters.
- The third number is the belt side angle.
- Old belts wear narrower, so compare both the printed number and the vehicle application.
- Do not assume every 50cc or 150cc scooter uses the same belt.
Source Notes
Belt marking guidance was checked against scooter CVT references including 49ccScoot’s belt identification guide and scooter belt product listings that explain the length-width-angle format. Match the old belt number and scooter model before ordering.
