Free printableMeasure partsTSP-ME-15
Oil seal size reverse lookup for scooters and ATVs
Seals are described by three numbers and nothing else. Measure them and buy from a bearing factor rather than a scooter shop.
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TSP-ME-15 · version v1.0 · September 2026. Opens in your browser's PDF viewer, where you can print directly.
The problem it solves
Oil seals are among the cheapest parts on the machine and among the most commonly bought at the highest markup, because owners buy them from scooter parts sellers by model rather than from bearing factors by size. A seal has no model. It has three dimensions and a lip type.
Like bearings, seals are one of the few genuinely standardised things on these machines. A seal is described by inside diameter, outside diameter and width, in that order, and that description is complete — any supplier anywhere can fill it.
That means the answer to "what crank seal does my scooter take" is not a model number. It is three measurements you can take from the old seal in about a minute, and once you have them the part is available from any bearing factor for a fraction of what a scooter shop charges for the same item in a branded bag.
The only complication is the lip: single or double, with or without a dust lip, and with or without a garter spring. Record which, because a seal of the right size and the wrong lip will fit and leak.
The mistakes this sheet exists to prevent
- Buying seals by machine model, at several times the price of the identical part from a bearing factor.
- Measuring the seal's outside diameter after it has been prised out and distorted.
- Recording the three numbers in the wrong order. The convention is inside, outside, width.
- Ignoring the lip type, so a correctly sized seal fits and still leaks.
- Fitting a new seal into a housing scored by the old one, or onto a shaft with a wear groove.
Who it is for
- Anyone chasing an oil leak at the crank, gearbox or fork
- Owners who want to buy from a bearing supplier rather than a scooter shop
- Anyone rebuilding an engine with the seals already removed
What is on it
- How a seal size is written, and in what order
- Measuring an old seal without letting distortion mislead you
- Lip and spring types, and why they matter
- A record block for every seal on the machine
How to use it
- 01Measure before you prise the seal out if you possibly can — removal distorts it.
- 02If it is already out, measure the housing bore for the outside diameter and the shaft for the inside.
- 03Record the lip arrangement and whether there is a garter spring.
- 04Check the shaft for a wear groove before fitting a new one in the same position.
Use it with the registry
Other sheets you may want
- Wheel bearing size chart and reverse lookupMeasure bore, outside diameter and width, read the bearing number off the table. Works without knowing what the machine is.
- 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 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.
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-15 and the version so we know exactly which sheet you mean. All printables.