Hi, Neil if your headlight is not working, intermittent, only one beam works, keeps burning out, blinking, dim or surges from bright to dim to bright the first thing you need to check is the headlight bulb for damaged filaments then check your light circuit fuse, then check your head light bulb socket ground wire for a clean tight connection, that being said the usual suspects are:
1. Faulty ground or power supply wire to headlight bulb socket.
2. Worn down solder contacts or loose fit of the bulb base in the socket due to vibration.
3. Worn, chafed, or broken wires in the light circuit.
4. Corroded, broken, or loose pins/sockets in wire connectors.
5. Faulty hi/low beam switch.
6. Faulty ignition switch.
7. Fuse is good but no continuity on both sides.
8. Faulty headlight relay.
9. Faulty wiring between battery positive and headlight bulb socket.
10. Weak charging alternator/generator/lighting coil
11. Faulty voltage regulator/rectifier ground or overcharging.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
Newbie on Keeway Superlight problem after problem
Ignition turned on but no power at all Bike just stop working
Keeway superlight 125 service manual
Keewayparts com Genuine Keeway Parts Shipped Worldwide KEEWAY Speed 125 User Manual
Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e