When I brought my KTM it had some strange headlight/nosecone fitted and to this day iv never found a bulb to fit it or seen a bulb like it.
I took it of and fitted the original back on and hid it in the shed.
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Picture would be great but you describe a holder.... if the holder is separate to the housing then it maybe a H1 https://en.wikipedia.org/wiki/H1_lamp
It has 3 metal tangs on it and the earth tang pushes down the side of the bulb earthing it out
It's a bayonet fitting
BA20D? That's the only bayonet headlight fitting I know. Usually used on cheap off-brand 125cc bikes.
Yeah that's the one thanks guys for your help .are the any good I mean lifespan and output
They were the bulbs in Chinese 125's. Seem to remember them being a bit crap but good enough to not ride in to a tree at night.
THere is a conversion plug in kit to an H4 I think.