What does the jolt feel like? If you can get "wet enough" or an injured finger, 12V burns not tingle. A "jolt" is either spark or the primary of the ignition coil, or a relay coil "kick."

Possibilities: tach wire, horn relay (button) circuit, any other relays you've added like driving lights that are "near" the column physically or wiring / electrical.

It also might be something REALLY far out like.............You said grinding noise, HOW ABOUT THE STARTER

Maybe the engine block is not properly grounded, and something caused the starter to attempt to engage.

I "did that" once in my old 70 RR I had the battery trunk mounted, and had been doing something --I think a cam change-- somehow the frame / body to block jumper got not reconnected. First time I tried to start it, mucho sparko's came from the clutch linkage and CRAPPED A CLUTCH LINKAGE RETAINER CLIP right out on my foot!!​