Free printableElectrical and wiringTSP-EL-05FLAGSHIP
GY6 CDI connector pinout — map your own
Map your own connector with a meter, because there is no universal pinout and every chart you will find contradicts another.
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TSP-EL-05 · version v1.0 · September 2026. Opens in your browser's PDF viewer, where you can print directly.
The problem it solves
Search for a CDI pinout for these machines and the results are a spam repository, an AI-generated content farm, a Pinterest image of unknown provenance and a forum thread from 2011. People wire from those, and when the machine does not run they buy another CDI.
We looked hard for an authoritative pinout and there is not one, because there is not one to find. Experienced owners describe factory loom colours as varying between machines of the same brand and the same model — one put it as whatever was left on the wire spool rack at the harness factory. Every widely circulated colour chart we examined disagrees with at least one other.
That makes a printed pinout worse than nothing, because it will be believed. A meter and twenty minutes gives you a pinout that is definitely correct for your machine, and this sheet is the structure for recording it.
The method is function-first. Rather than asking what a wire's colour means, you establish what each pin does: which is earth, which is switched by the key, which goes to the coil, which comes from the pickup, which comes from the charge coil. Those are all testable, and once you have them the colours are irrelevant.
The mistakes this sheet exists to prevent
- Wiring from a chart found online. There is no universal standard and the charts contradict each other.
- Buying a CDI before checking the earths and the connectors, which produce the same symptom for nothing.
- Assuming the connector on a replacement CDI is pinned the same way as the one you removed.
- Drawing the connector without noting which half you drew. The loom side and the component side are mirror images.
- Probing a live ignition circuit without insulated tools.
Who it is for
- Anyone fitting a replacement CDI whose connector does not obviously match
- Owners tracing a no-spark fault beyond the basics
- Anyone who has been sent a CDI with a different plug
What is on it
- Why no pinout is printed, stated plainly
- A function-first mapping method using a meter
- Large connector-face drawing areas for both halves
- A pin-by-pin record with the tests that identified each
How to use it
- 01Disconnect the battery before unplugging anything.
- 02Draw the connector face and label which half you drew — loom side or component side.
- 03Identify pins by function using the tests below, not by colour.
- 04Record the colour you found against each function anyway. It is useful on YOUR machine, and only on yours.
Use it with the registry
Other sheets you may want
- GY6 no spark diagnostic chartWorking back along the ignition circuit from the plug, one component at a time, without replacing anything on spec.
- GY6 wiring colour and continuity notes sheetThere is no universal wiring colour standard on these machines. This sheet records the one your machine actually uses.
- Scooter earth and ground connection checklistA corroded earth produces the same symptoms as a dead ignition component, and costs nothing to fix. Check these before buying anything.
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-EL-05 and the version so we know exactly which sheet you mean. All printables.