A funny thing happen to me on the way to a repair

I have a customer's Mk3 in for a transmission rebuild (303640/F101398) while stripping it down I noticed a single phase charging system which appears to have its wires in the OE position; the rectifier is correct for a single phase, but it has twin zenners. I could be wrong on the frame number; the stamping is a bit vague and my eyes are getting on. There are a lot of "hacks" on this motorcycle, but the charging system appears correctly installed; no obvious cuts in the charging harness.

To anyone's recollection were the MK3s ever fitted with single phase charging systems from the factory?

MKIII's are single phase, but have a bit more output and they do have 2 zener diodes from the factory.
Sounds like the charging system is original.

RoadScholar said:

To anyone's recollection were the MK3s ever fitted with single phase charging systems from the factory?

Click to expand...

Yes-all of them (RM23)! Note that the rectifier is a two-diode 2DV 406.
http://www.nortonownersclub.org/support ... alternator



http://britmoto.com/manuals/Manuals/850_man.pdf
Electrical Section J.

Thanks Guys!

JPN Replicas had them too (RM23).

303xxx is a Mk 1 engine number ??

My '72 came with dual Zeners ... the original stator and rotor ate themselves years ago ... removed zeners when going to boyer and pod .... I didn't realize some came with just one zener ...
Craig

Craig said:

I didn't realize some came with just one zener ...

Click to expand...

Only the 850 MkIII (and JPN Replicas) had the high output 180W RM23 alternator with two Zeners, other Commandos '68-'74 had the 120W RM21 alternator and one Zener.

RoadScholar said:

I have a customer's Mk3 in for a transmission rebuild (303640/F101398)
To anyone's recollection were the MK3s ever fitted with single phase charging systems from the factory?

Click to expand...

OF course you might realize the VIN and frame quoted are NOT MKIII. 325xxx and up are MKIII, whats up with that?
Surprised you were not aware that all MKIII use the single phase 180W 2 diode-2 zener system.

Today NENO north shore group is having it's regular 1st and 3rd Saturday tech session for all members. It seems to be helpful since there are so few shops in New England, or in the country for that matter, that appear to be competent with nortons. We constantly get members and people coming to tech sessions among other things, to have repair shop induced problems diagnosed.
example:
A month ago we had a very big bux engine in here for trouble shooting, built by a norton shop.
Was I impressed? A diagnostic dyno run and several hundred dollars of charity work was performed for the member... not the shop IMO it still needs more work.

http://nneno.org
http://nneno.org/member-forum

Rohan said:

303xxx is a Mk 1 engine number ??

Click to expand...

330640, got new glasses...