Free printable · Measure parts
GY6 belt size chart and measuring sheet
How 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.
Layout preview of page one. The PDF itself is typeset text, not an image.
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3 pages. No account, no sign-up, no newsletter. Print it, copy it, hand it to somebody else.
Version v1.0 · September 2026. Opens in your browser's PDF viewer, where you can print directly.
The problem it solves
Drive belts are the part most often ordered wrong. The marking wears off first, the belt is worn narrower than it left the factory, and the listing you are buying from quotes three numbers with no explanation of which is which. People end up guessing from the engine size, which is exactly the assumption that does not hold on these machines.
Who it is for
- Anyone whose belt has snapped and who has no old part number to work from
- Owners comparing a worn belt against a new one before fitting it
- Anyone buying from a listing that quotes only three bare numbers
What is on it
- What each of the three numbers on a belt marking means
- True-size width bars from 15mm to 22mm to lay a belt against
- A printed calibration rule so a mis-scaled printout is caught first
- How to measure length on a belt with no markings
- A wear comparison block: new width against measured width
How to use it
- 01Check the calibration rule with a steel rule before you measure anything.
- 02Clean the belt. The markings are usually still there under the dust.
- 03Measure the top width across the widest part of the belt, not at a worn edge.
- 04Record what you measure, then compare it against what a listing claims — not the other way round.
Use it with the registry
Other sheets you may want
- Variator roller size chart and measuring sheetDiameter, width and weight are three separate things, and a roller set is only interchangeable on all three. A record sheet with true-size circles and a weighing block.
- Mystery part measurement sheetYou are holding a part. Nobody knows what it is called. This sheet records everything a supplier needs in order to find it for you.
- Before you order a scooter part: checklistTwelve checks that take ten minutes and prevent the single most common expensive mistake these machines produce.
Free to print, copy, and share — including in forums, clubs and workshops. If you find a mistake on one of these sheets, tell us and it gets corrected. Every sheet carries a version so you can tell which one you have. All printables.