Original owner of my own barn find

Hi all,
I am the original owner of a 1974 850 Commando with less than 2000 miles on the odometer. It has been hiding in my own barn for over 30 years. I was able to keep it pristine for the first 20 years but it spent the last 10 in a moist part of the barn so there are some surface rust issues.

My son has a new Triumph Daytona 675 and I need to get my Norton going so we can ride together. I've been using his old Honda 750 Nighthawk but it just isn't me.

While cleaning things up I removed the RH support plate and the zenner diode and I can't remember where to hook up the red ground wire. It is in the same loom as the zenner wires and looks like a primary ground wire. The round lug connecter is relatively large but smaller than any of the bolts I can find in the area. Any ideas ? I know I am going to feel really foolish when I find out where it goes.

Thanks in advance for the help.

This is a really great board with lots of fantastic Information.

between the z plate and diode. if you have any heat transfer grease use it also


windy

I just checked my '74 and the ground is under the rear bolt for the foot rest.
Mike

Windy,
I thought about "behind" the zenner on the "inside" of the Z plate but that would then provide ground for the zenner only (maybe that's what it is supposed to do). If it was a general ground that is a long path to get back to the frame.

Mike,
That is where I though it went but it wont fit. The bolt is too large to fit the hole in the lug. I could drill it out but that's not where it came from.

Thanks guys ... any more suggestions ?

The Z plate is well earthed to the frame in quite a few places, however this additional earth wire originally went behind the zener and I think is specifically to make sure that the zener itself is earthed directly to the wiring loom.

KickStarter
I am the same as Mkjen’s set up. I checked my 850 and it also has a bolt running through the rear footrest hole…(the front foot rest holes are studs)… the connection is from the inside with the red earth wire eyelet between that bolt head and the Z plate. The spade with the Brown /Blue wire is attached to the zener diode male spade connector. The Aluminium Z plate is a great big heat sink for the zener diode to dissipate heat when the battery is not up taking power. Hope that helps.
Regards,
CNN

The footrest is secured with a bolt at the rear which threads through the plate and there is a nut and washer to attach the ground ring. This bolt is 5/16-18 and all my Commandos have a ring large enough to fit over this bolt. The other two fasteners are studs as are all three on the left side, so this is the only reason for using this bolt in a tapped hole and using a nut and washer!
My '73 came from the dealer this way and I have always built my Commandos with this set up.

It is important that the zener have a good contact with the heat sink (Z-plate) or it will fail. Placing the ground ring on the zener stud can compromise this. I always use heat sink grease on the brass face of the zener when installing on the plate.

Thanks guys !!!
It seems so obvious now.
This is the first of many questions to come. I hope all the answers are this easy.