Two usual causes Warren

1 is the bike fitted with a regulator? check connections to this and that it has a clean earth fixing

2 is the battery fitted, topped up and in good condition?

Thats about it

...Paul

Firstly thanks for reading.

I have a 82 RS 125, I am just finishing off a total rebuild but I am having difficulties with the electrics.

When the bike revs the lights get brighter till they blow, so I replaced the rectifier but this did not seem to help.

I have checked the wiring and earth connections and all seems fine...

Does anyone have an idea what is causing this?

Cheers

Warren