Battery ground arcing

[Ken Talbot]

Scott brought his '78E over from Calgary this weekend so we could check out a few things, do a tune-up, etc, etc.

At one point while we had the sidecovers both off and I hit the starter button, Scott noticed some serious arcing happening where the battery ground cable attached to the frame. I shut it down then started it again so I could see and sure enough, it was arcing from the screw head across to the frame!

When checked, the screw was tight. However, when we removed it, the threads were pretty badly corroded. I also noticed the head of the screw was quite warm, perhaps from the resistance to the major current while starting. We cleaned up the screw, the washer, and the mounting hole, put it all together and the arcing went away.

I've never seen this before, and it is not something you would tend to see unless you were looking for it. I'll have to make a point of watching for this on the rest of the fleet.

[strom]

I had a similar problem... well.. not similar, but it might enlighten some...

When I first put the engine back in the bike after 6 years of sitting in boxes, I tried to crank it with the starter motor (don't worry, I put it in sync and checked by turning it by hand).
The starter relay went click and the oil light turned off... the engine didn't turn.
OK I said... the battery is empty... not full anyway, since it was new and I didn't charge it (it should be dry charged, or at least so the salesdude said). Charged the battery.... turned over the engine once, barely.
That's not right... then I noticed the clutch cable was hot. Hmmmm.... I pulled in the clutch, as I always do, but the friction wasn't nearly enough. Ergo, the only apparent ground connection from the engine to the frame was the cable.... offcourse, the engine sits on rubber mounts.
I stuck a screwdiver between the shi(f)t lever and the shaft (no middle drive on yet).
Tried again, sparks flew from the screwdriver, the engine turned over happily...
OK I said, I'll put an extra wire running from the engine to the frame. However I didn't get to it till the exhaust was on. Now, the exhaust is on rubber mounts too, but the engine is still grounded somewhere. I'll install that wire just in case.... one never knows.

LP

[Dragonrider]

Ummmm . . . yeah . . . you definately need the engine ground strap/wire even though the engine may be grounded somewhere else.

A bad connection here can fry your voltage regulator, and especially when starting, things can ground back through other things . . . frying expensive and hard to fine whatsits.