OK, was out playing a little on a buds Indy 500 tonight. The headlight, tach & speedo light along with the lights for the heatd grip & thumb warmers would go dim. Seemed to do it in the beginning when sled was started. It would last about 5 minutes and then all was ok.

We shut the sled down for about 10 minutes and when we started it, same thing over again. They wouldn't go out completely, but down very low where you wouldn't see much on the trail.

Any ideas on what it could be ?

Does it do it at all rpms?

On my 1994 Indy 440 when im running down the trail my headlight and dash lights both dim when i let off the throttle. Not to the point i cant see them though. When I get back on the throttle everything brightens right up.

Voltage regulator

x2

yep sounds like you are in need of a voltage regulator. retail is about $50.