Free printable · Measure parts
Chinese scooter bolt, thread and spanner card
Why an 8mm bolt sometimes takes a 12mm spanner and sometimes a 13mm, how to identify a thread without a gauge, and a true-size thread pitch scale.
Layout preview of page one. The PDF itself is typeset text, not an image.
Download — free, no email
2 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
Chinese powersports fasteners follow Japanese head-size conventions more often than European ones, which is why a bolt that a European chart says takes a 13mm spanner takes a 12mm on your scooter — and why people round off heads with the wrong size. The bolt itself is standard; the head across-flats is not.
Who it is for
- Anyone building a socket set for one of these machines
- People replacing a lost or rounded fastener with no sample to match
- Anyone ordering a bolt online from a measurement rather than a part number
What is on it
- ISO metric coarse thread pitches
- Head across-flats under both the European and the Japanese conventions, side by side
- How to measure a bolt correctly — diameter over the thread, length excluding the head
- A true-size thread pitch comparison scale
- A fastener record block for a job in progress
How to use it
- 01Check the calibration rule before using the pitch scale.
- 02Measure bolt diameter across the outside of the threads, not across the shank.
- 03Measure length from under the head for a standard bolt, and from the top of the head for a countersunk one.
Use it with the registry
Other sheets you may want
- 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.
- GY6 engine identification chart and worksheetThe measurements and observations that tell you which engine you have when the label is gone — recorded in the order a parts supplier will ask for them.
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.