CVT service record for a GY6 or Chinese scooter

The problem it solves

The CVT contains the parts that wear fastest and the parts people most often replace with something different from what came out. Two services later nobody remembers what belt is in there, what the rollers weigh, or whether the clutch springs were changed — so the next diagnosis starts from nothing.

A scooter transmission has no gears to check and no dipstick to read, so it tends to be ignored until it squeals, judders or stops driving. By then the question is not just what failed but what was in there, and on a machine that has had two or three owners nobody knows.

It is also the system people modify. Roller weights get changed to alter how it pulls away, clutch springs get swapped, and a belt gets fitted because it was the one in stock. Every one of those is a legitimate thing to do and an illegitimate thing to forget.

This sheet records what went in and what it measured. Do it twice and you have a wear rate — how many miles your belt lasts, how fast your rollers flatten — which is worth more than any published interval, because it is about your machine and your riding.

The mistakes this sheet exists to prevent

• Replacing a belt without recording its marking, so the next one is a guess again.
• Fitting new rollers without weighing the old ones, losing the only record of what the machine was set up with.
• Replacing a belt and leaving flat-spotted rollers, which chews the new belt.
• Cleaning the clutch and variator with something oily, which is how a freshly serviced CVT ends up slipping.
• Not recording mileage at each service, which makes wear rates impossible to work out later.

How to use it

1. 01Weigh and measure the old parts before you bin them. That is the whole value of the sheet.
2. 02Record the mileage every time, even approximately.
3. 03Note what you changed AND why, so a setup change can be undone if it was wrong.
4. 04Keep it with the machine, not in a folder indoors.