Free printableMeasure partsTSP-ME-10
How to measure and identify a Chinese scooter carburettor
Carburettors are sold by a bore size and a family name that nobody explains. Measure yours and record the fittings before you order one.
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TSP-ME-10 · version v1.0 · September 2026. Opens in your browser's PDF viewer, where you can print directly.
The problem it solves
Carburettor listings quote a bore in millimetres and a family name, and buyers match on the photograph. What actually decides whether one bolts on is the intake spigot diameter, the throttle arrangement, the number and size of the hose spigots, and whether it needs an electrical connection for the choke — none of which the bore size tells you.
There is no neutral reference for Chinese scooter carburettors. Search for one and you get product pages, all of which want you to buy the one they are selling, and all of which describe it in terms that only make sense if you already know what you have.
The useful facts are physical. A carburettor has to slide onto an intake spigot of a particular outside diameter, accept a throttle cable of a particular type, take the hoses that are already on the machine, and if it has an automatic choke it needs a matching electrical plug. Get those four right and the bore size is a tuning question rather than a fitment one.
So this sheet records the four, and leaves the bore to be recorded rather than recommended — changing bore size changes how the engine runs, which is beyond what a printed sheet can responsibly advise on.
The mistakes this sheet exists to prevent
- Ordering on bore size alone. The bore does not determine whether it fits the intake.
- Measuring the intake spigot's inside diameter when the carburettor slides over its outside.
- Forgetting the auto-choke plug, then finding the new carburettor has a different connector or none.
- Not counting the hose spigots before removing the old one, leaving a hose with nowhere to go.
- Assuming a bigger carburettor is an upgrade. It changes fuelling, and fuelling is not something a worksheet can set for you.
Who it is for
- Anyone replacing a carburettor that has gummed up beyond cleaning
- Owners of a machine where the previous carburettor was already a replacement
- Anyone trying to work out which of a dozen similar listings matches their machine
What is on it
- The four measurements that decide whether it bolts on
- A hose spigot count and sizing block
- Throttle and choke arrangement record
- A tracing area for the mounting flange
How to use it
- 01Check the calibration rule before measuring anything.
- 02Photograph the carburettor in place, from three angles, before you disconnect a single hose.
- 03Measure the intake spigot's OUTSIDE diameter — that is what the carburettor clamps onto.
- 04Count the hose spigots and note where each hose goes before removal.
Use it with the registry
Other sheets you may want
- Chinese scooter vacuum hose and fuel line worksheetDraw your own routing before you take it apart. There is no single correct diagram for these machines, and the only one that matters is yours.
- 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 this sheet, tell us and it gets corrected. Quote TSP-ME-10 and the version so we know exactly which sheet you mean. All printables.