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by Mal Marsden - 06/16/22 7:00 pm
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Allan G, gavin eisler, Kev Ev, RobJP
Total Likes: 7
Original Post (Thread Starter)
#850570 06/03/2021 1:07 PM
by Kev Ev
Kev Ev
Hi all,

I am about to start making up the new wiring harness for my 1966 A65 Lightning.

I thought I would share my details, along with my electrical schematics/wiring diagram in the hope that it may be of some help to other members of this forum.

I work as an electrical controls engineer and have been doing this for some years now. My duties include the design and drawing of electrical circuits for the automated production machinery that is built by the company I work for. The electrical controls systems are pretty complex and usually consist of dozens to hundreds of pages.

The A65 system is pretty simple and I have drawn it up, along with my modifications, in a way that keeps everything somewhere close to how it is laid out on the bike. Not exactly to scale, but something that makes sense and is easy to follow.

I like to keep the load off things like handlebar switches, so I have used a couple of relays. One is a changeover relay for the headlight main and dip beams and the other is a simple on/off for the horn. I have also fitted a neat little 4 way fuse box, with continental spade fuses to give a little added short circuit and overload protection to the equipment.

I am using a 3 phase alternator with a Podtronics regulator and a Boyer Mk3 Ignition system. The battery is a Motobatt MB9U AGM type.

If this is of any help to anyone I can let you have this wiring diagram in AutoCad .dwg or .pdf format.


Kev E
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Liked Replies
#850961 Jun 7th a 09:35 AM
by Stuart
Hi Gavin,
Originally Posted by gavin eisler
Originally Posted by koan58
I agree with Stuart that a relay for the ignition switch is a good idea.
Originally Posted by Stuart
Not my idea, I've never fitted one; Gavin advised the idea?
Not me
blush Ooops, sorry 'bout that ... it was/is somewhere in the thread before Dave's first post ... help

(or "It wasn'y me, a big boy did it an' ran away"? grin ).

Originally Posted by gavin eisler
my Boyer is not relay fed, I reckoned the ignition switch should manage 3 amps.
thumbsup My thinking too.

2 members like this
#850571 Jun 3rd a 01:30 PM
by RobJP
That's brilliant - thanks very much Kev!
1 member likes this
#850853 Jun 6th a 09:29 AM
by gavin eisler
gavin eisler
I used a similar concept, ended up with 4 relays,
1 master relay , energized by ignition switch, 25 A
1 Lighting relay , 1" cube
1 main beam/ flash relay, this gives the option for a spot light if wanted. , 1" cube
1 dip relay, micro relay in lamp shell

i used thin wires for the control switches and thick wires for the relays/ loads.

All japanese connectors, helps a lot with space saving in the headlamp.
No horn relay, I thought 5 was too many. So far no vibration failures of relays,. They are scattered around the bike, master under the coil bracket .
Lighting bolted to air box, mainbeam behind headstock,
dip in lamp shell.
1 member likes this
#850958 Jun 7th a 08:46 AM
by gavin eisler
gavin eisler
Originally Posted by Stuart
Hi Dave,
[quote=koan58]I agree with Stuart that a relay for the ignition switch is a good idea.
Not my idea, I've never fitted one; Gavin advised the idea?

Not me, my Boyer is not relay fed, I reckoned the ignition switch should manage 3 amps.

Originally Posted by koan58
I don’t know why folk use a separate relay for main and dip, a single switching relay such as will do the job.

i did this because i wanted a spot light option, also, the flash button will power the main beam relay if dip is in operation, which wont work with one relay for dip and main beam.
1 member likes this
#850919 Jun 6th a 10:15 PM
by Stuart
Hi Dave,
Originally Posted by koan58
Perhaps I misunderstood this statement of yours?
Originally Posted by Stuart
I've been fitting similar to Britbikes since my first rewire over the '82/'83 winter. Changeover relay for the headlamp, imho you're missing a trick - it might "keep the load off" the handlebar dipswitch but the headlamp current is still across the ignition and lighting switches contacts.
as there isn’t an ignition relay, the lights are presumably supplied independently of the ignition switch?
Correct. Same paragraph:-
Originally Posted by Stuart
My T100 also has an Ammeter, its relay #30 terminals are connected to the same Ammeter terminal as the reg./rec. -ve wire, the headlamp draw shows on the Ammeter but then bypasses all the switches.

Originally Posted by koan58
Can your lights be on when the ignition is off?
No; from my previous post:-
Originally Posted by Stuart
an on/off relay for each headlamp bulb filament, when the ignition switch is off, there isn't any power to the dipswitch (that switches the two relays) so both relays are off, so both headlamp bulb filaments are off;

Originally Posted by koan58
Originally Posted by Stuart
. because I've never switched the headlamp current with the ignition switch, a changeover relay doesn't work for me, because terminal #30 is connected to terminal #87b #87a when the relay is 'off'; i.e. whichever headlamp bulb filament was connected to #87b #87a would be on and working even when the bike was parked;
this relay is nothing more than a dipswitch,
It might be for you, because you supply its terminal #30 from your "ignition relay", or Kev intends to supply his from the "Light Switch"; in either case, the power to the changeover relay terminal #30 is cut when the ignition switch is off.

Otoh, I supply the headlamp either direct from the battery or from the aforementioned Ammeter terminal; the relays themselves are the only switches between battery -ve and the headlamp bulb filaments.

Anyone using relays to supply the headlamp is using two relays: either a relay switched on/off by the ignition switch, which supplies the changeover relay switched by the dipswitch ... or two relays switched by the dipswitch. In the latter case, as I say, ignition switch off, no power to the dipswitch, both headlamp relays off. thumbsup


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