What's that on the back of the rotor?

[scraf]

I managed to break off a piece of my rotor when doing a quick repair job on the side of the road in the dark, and even though it was still working have replaced it.

However, I have have absolutely no idea what the extra bits actually do, can someone enlighten me.

( photo is of the broken one )

[WGB]

It's a bit hazy but I assume it's a spring loaded centrifugal weight that opens at a predetermined number of revs and cuts the High tension circuit - this was a common mechanical rev-limiter before electronics took over.

Bill

[scraf]

There is indeed a spring in the mechanism, sorry for the bad photography, bought a camera with too many buttons.

Thanks WGB, puzzle solved.