Free printableTroubleshootingTSP-TS-08
GY6 belt keeps breaking — what is destroying it
A belt that fails repeatedly is not a bad belt. Something is destroying it, and it is usually one of six things.
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TSP-TS-08 · version v1.0 · September 2026. Opens in your browser's PDF viewer, where you can print directly.
The problem it solves
When a belt fails twice, the usual conclusion is that the replacements were cheap. Sometimes they were. More often something in the transmission is destroying them — a wrong length, a scored pulley face, a seized roller, oil contamination — and a third belt will go the same way.
A drive belt is a consumable and it is supposed to wear out. What it is not supposed to do is fail early, twice, in the same way. When that happens the belt is a symptom.
The most important clue is free and most people throw it away: the broken belt itself. How it failed — shredded from one edge, snapped clean across, cogs stripped off, glazed and then parted — points at quite different causes. Keep the pieces and look at them before ordering the next one.
The second clue is the case. A scored pulley face, a roller with a flat, or any trace of oil where the transmission should be dry will each shorten a belt's life dramatically, and all three are visible the moment the cover is off.
The mistakes this sheet exists to prevent
- Throwing the broken belt away. How it failed is the best evidence you will get.
- Fitting a new belt into a case with oil in it, which will glaze the new one within weeks.
- Assuming a belt that fits is the right length. A belt slightly too long or short runs at the wrong height in the pulleys.
- Blaming belt quality twice before looking at the pulley faces the belt runs on.
- Ignoring a rider weight or load that the transmission was never set up for.
Who it is for
- Anyone on their second or third belt in a short time
- Owners whose belt life is much shorter than other people report
- Anyone who has just had a belt let go and wants to know why
What is on it
- How the belt failed, and what each failure mode points at
- The six causes, each ending at something visible
- The case inspection that finds most of them
- A record so belt life becomes a number rather than an impression
How to use it
- 01Keep the broken belt and lay the pieces out before you order anything.
- 02Take the cover off and inspect before fitting the replacement.
- 03Measure the new belt against the old one's marking, not against the worn old belt.
- 04Record how many miles each belt lasted. Two entries give you a real interval.
Use it with the registry
Other sheets you may want
- GY6 CVT slipping, juddering and squealingThree different noises from the same case, and they mean different things. What to look at with the cover off, in order.
- GY6 belt size chart and measuring sheetHow to read the three numbers printed on a scooter drive belt, how to measure a belt that has no readable markings left, and a record sheet for the one you have.
- CVT service record for a GY6 or Chinese scooterThe transmission is the highest-wear system on a scooter and the least documented. One sheet for everything that goes in it, with the measurements taken each time.
Free to print, copy, and share — including in forums, clubs and workshops. If you find a mistake on this sheet, tell us and it gets corrected. Quote TSP-TS-08 and the version so we know exactly which sheet you mean. All printables.