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Hi,needing some help/advice my scooter starts and runs but when I put the lights on they don't work only when the engine is revved hard and also brake light stops working but when lights turned off brake light works ok, also engine starts to splutter when lights are on? Any ideas,thanks mark

You don't say what kind of ignition / lighting system you have, if it's AC or DC etc.

First thing to do is get a multimeter if you don't already have one and learn to use it. Then check all your connections are tight, in the right place and all your earths are good and on clean metal (scrape the paint off), including the one between the frame and the engine and the one on the regulator / rectifier. Blue / red plastic crimp on connectors are always a suspect.

After that check the condition of any sleeving and plastic on the wires themselves for cracking / fading / brittleness especially if it's the original loom. Check for continuity one end to the other of each wire and check all wires for shorts between them or shorts to earth.

IMO it's a wiring or earth problem but no harm in eliminating components by swapping them for known good or working parts.

It's running a bgm stator and 12v,they must have been working only been mot'ed for about a month this is only the second time it's been out after paint and rebuild,will check all conectors and earth,thanks.

This only a stab in the dark, but I would be looking at the earthing between the frame and the engine with the symptoms you describe.
Good advice there from Ross.

I'd guess that a wire is earthing out where it shouldn't be. Most likely in the headset.

It's only my best guess and most likely very wrong.

Captain Pugwash wrote:I'd guess that a wire is earthing out where it shouldn't be. Most likely in the headset.

It's only my best guess and most likely very wrong.

Good point Mark, when the lights are on it could short out, causing the same symptoms on an AC system.

All the advice above fails to rectify the problem, then think about the flywheel. This has the symptoms of a de-magnetised flywheel.

Knowledge wrote:All the advice above fails to rectify the problem, then think about the flywheel. This has the symptoms of a de-magnetised flywheel.

That was my second best guess

have you got earth and feed wires in right corrections in back light as you will have had it off to paint it just a thought as there probably two blacks in there and a pink ?????? Michael