Competition model wiring

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Competition model wiring

Postby Pharisee » Wed Jan 29, 2020 7:54 pm

I've been trying, without success, to find a wiring diagram for the C model with the 5 pin plug in the headlight shell. I had assumed that this was to facilitate the quick removal of the headlight but poking around in the wiring on my '56 model, I've found that the plug doesn't allow for the wiring to the headlamp dip switch which enters the headlamp under the switch panel and would all have to be removed to take off the headlamp. Doesn't that sort make the QD wiring plug a bit of a joke?
Of course, it could be that the wiring on my bike isn't original... which looking at it, I strongly suspect is the case.
The five pins in the plug are connected to:-

The battery -ve terminal.
The regulator "A" terminal.
The speedometer light.
The tail light.
Power to the horn.

Would that be correct?
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Re: Competition model wiring

Postby dave16mct » Wed Jan 29, 2020 10:11 pm

There is a supplementary competition manual G80CS 1956 but it doesn't have a wiring diagram. The only one I can find is in this: http://archives.jampot.dk/book/Owners_m ... CS_P11.pdf
Page 52 has a wiring diagram. Its for an alternator model but shows the comp headlamp plug so might help.
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Re: Competition model wiring

Postby Pharisee » Wed Jan 29, 2020 10:23 pm

dave16mct wrote:There is a supplementary competition manual G80CS 1956 but it doesn't have a wiring diagram. The only one I can find is in this: http://archives.jampot.dk/book/Owners_m ... CS_P11.pdf
Page 52 has a wiring diagram. Its for an alternator model but shows the comp headlamp plug so might help.
Dave.


Thanks for the effort, Dave but that circuit doesn't make any sense at all. For instance, it shows a connection from the ammeter to the lighting switch going via the plug and socket when both of those components are effectively inside the headlamp shell and are connected directly.
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Re: Competition model wiring

Postby Groily » Thu Jan 30, 2020 6:09 am

Could it be, John, that the lighting switch for the diagram illustrated on p52 was on the toolbox / a sidepanel not in the shell? (As per a lot of Triumphs, for example?)

I really don't know, just thinking on the keyboard really, but it's the obvious inference because the rectifier and alternator leads are shown as direct links to the switch, not through the multi-pin plug (which they'd need to be if the switch was in the headlight). The two ammeter wires would clearly need to go through the connector if the switch wasn't 'there'.

Another point would be whether or not you are intending to replicate the 6v three-wire stator wiring of the day, or going for something better, eg regulator/rectifier, 2 wire stator, 12v upgrade, etc. On every alternator bike I have got or have had (bar one), I have fitted either an A Reg 1 from Alan Osborn, or a Podtronics box, and 2 wire stator from Paul Goff, and gone 12v. On the 'bar one' I used an A Reg 6 to stay at 6v but gain the simpler wiring and greater reliabiltiy that comes with.

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Re: Competition model wiring

Postby ajsph » Thu Jan 30, 2020 6:32 am

I have this diagram
Poul
Diagram Socket & Plug.pdf
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Re: Competition model wiring

Postby dave16mct » Thu Jan 30, 2020 10:00 am

Nice one Poul!
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Re: Competition model wiring

Postby Pharisee » Thu Jan 30, 2020 10:28 am

Groily wrote:Could it be, John, that the lighting switch for the diagram illustrated on p52 was on the toolbox / a sidepanel not in the shell? (As per a lot of Triumphs, for example?)


Yes, Groily, I did think afterwards that may well be the case.

ajsph wrote:I have this diagram
Poul
Diagram Socket & Plug.pdf


That's brilliant, Poul. Exactly what I wanted. It would seem that my bike is wired exactly as it should be, which is good news. That diagram also gives the cable colours as well. The dipswitch is still wired in separately but hey ho... if that's the way it should be, who am I to argue :D
I'm still going to rewire the bike as some rubber insulation has perished and cracked off. I'm thinking of using the readily available vintage style cotton covered wires as I can't find anyone who supplies rubber insulated wires.
Also, I'm going to need a rubber cover for the 5 pin plug if I can find one anywhere :(
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Re: Competition model wiring

Postby raffles » Thu Jan 30, 2020 7:23 pm

Colin Farringdon who advertises in the JAMPOT can supply you the correct loom with the socket
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Re: Competition model wiring

Postby ajscomboman » Thu Jan 30, 2020 7:31 pm

I have to admit I did away with the comp plug/socket on my CS's as they are never likely to see the mud again. I went for the 6 1/2" road going headlight unit and hard wired the harness to avoid the aggro of the socket/plug corroding.

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Re: Competition model wiring

Postby Pharisee » Thu Jan 30, 2020 9:04 pm

ajscomboman wrote:I have to admit I did away with the comp plug/socket on my CS's as they are never likely to see the mud again. I went for the 6 1/2" road going headlight unit and hard wired the harness to avoid the aggro of the socket/plug corroding.


I've sort of compromised a little and replaced the old, yellowed, manual focus headlight unit with a later 6.1/2" Miller unit that takes a BPF bulb and has a pilot light. The plug and socket are totally corrosion free, so I'd like to keep that part original. The only problem is that the rubber cover, like a fair bit of the rubber insulation on the wires has perished. No doubt that's down to the hot, dry, Californian climate that it was in for 60 odd years. I guess it's unlikely that I'll be able to get a replacement without having to buy a complete harness, so I may have to be a bit inventive.

The wiring is very simple and can easily be replaced for a few of our fine British quids, particularly as I have all the terminals and crimping tools that I need. I can't really justify spending £60 or £70 on a commercially available harness that may or may not fit as well as one that I can make specifically for my bike. It wouldn't be my first, having made replacement wiring harnesses for my two other AMC machines and my two Triumph twins. Anyway... It'll give me something to do over the next week or two :D

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