Free printable · Troubleshooting
GY6 no spark diagnostic chart
Working back along the ignition circuit from the plug, one component at a time, without replacing anything on spec.
Layout preview of page one. The PDF itself is typeset text, not an image.
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3 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
No-spark is where the most money gets wasted, because the standard advice is to replace the CDI — the most expensive part in the circuit and one of the least likely to have failed. The circuit has around eight elements, and seven of them can be checked before you buy anything.
Who it is for
- Anyone who has confirmed there is no spark and does not want to shotgun parts at it
- Owners whose machine cut out while riding and will not restart
- Anyone who has already replaced a CDI and still has no spark
What is on it
- The ignition circuit listed as a chain, in the order worth checking it
- A yes/no branch at each element
- A record block for meter readings
- The earth and kill-switch faults that mimic a dead ignition component
How to use it
- 01Disconnect the battery before unplugging connectors.
- 02Check the cheap and free things first: earths, connectors, the kill switch.
- 03Record readings even when they look normal — a normal reading is evidence too.
Use it with the registry
Other sheets you may want
- Chinese scooter won't start: diagnostic chartA structured way through the four things an engine needs, ending at an observation you can make rather than a part you should buy.
- 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.
- Spark plug record and reading logThe plug is the cheapest diagnostic instrument on the machine. A record of what it looked like each time turns it into a trend rather than a guess.
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.