Gimpy left cylinder

Thanks for the update Sheffy and I'm glad it's working out for you.

Sheffy's created a number of ground points to insure a proper circuit to the spark plugs. I’m measuring 1.6 ohms between the battery lug and the spark plug base on my 74 850. Seems small but without a reference, there’s no way to be sure. Anybody have a definitive reading?

RFW has wrote about this for years. He has a great paper on the subject that is here: http://www.gabma.us/elec/proper_grounding.pdf
If you can't stand the background reading skip to single point ground.
Norton's have a tendency to brake the wires (three in most I have seen) at the head steady from the harness due to vibes. There are good ground wires in the stock harness you can use and using a meter to find each end of them is worth the time. Getting to concept straight in your mind will help when trouble comes along on the road.

Now there's more to this story... Started it up last night when it was dark just to ride it around the neighborhood so I had to have all the lights on, as opposed to before when only the ignition was hooked up. Got halfway around the block and it started stumbling again, to the point where by the time i got back around to my place it could barely make it into the garage under its own power. Quick jumped off and checked battery voltage with everything still on... 9.6V. :shock: It had been on the Battery Tender the night before and read 12.7V or so before I started it. Tried getting it load tested but it's only rated at 85 CCA and the lowest any of the local parts stores go is something like 150 CCA, so i gave it the benefit of the doubt and assumed it was ok. It did pass the informal load test of leaving the lights on for 2 minutes, though marginally.
So I put a little conventional battery from my RD350 in it as a test. Even after 15 minutes running around the development with no recharging from the alternator that little thing was still at 12.5V. Soooo.... i guess the battery wasn't helping either.
Lesson #2: Never just assume your battery's fine. Even if it's new and shows up good on a voltmeter, it doesn't mean anything once the bike's on and running. Thank god for warranties.

Gene,
After all my grounding, which i'll probably leave in place after this, i'm getting about .3 ohms between plug and battery. The absolute lowest my multimeter ever reads is .2 ohms though so it may be even less than that. Do you have any grounds hooked directly to the head somehow?

Sheffy, no, only frame grounding, although it does have a relatively new harness. I've always felt that the spark quality could be improved so I may try a temporary jumper this Spring and see what happens.