Originally Posted by Al.Fisherman
Do not use the frame as a ground.
Gonna hafta beg to differ on this 'un Al - as the engine case itself is a "ground" and it is in direct contact to the conductive material the frame is made out of, it's already a ground & ya might as well avail yourself of it. Attaching the ground wire to the frame only insures better contact.
All of my builds use the chassis as a ground, including my aluminum Schwinn w/one of Norm's white wire lighting kits - which I've installed w/only a positive lead going to them, completing the circuit by attaching the negative to the frame (as an example of harness simplification/reduction possible with chassis grounding).
Interestingly, I've never suffered an electrical issue... (ssh Murphy's listening) well, other'n my plug wire falling out lol - I s'pose that doesn't really count tho