just wanted to say Hi since I am new ti this site and nortons.

I recently started a project for a dear friend of mine, Its a 72 norton commando, that hasn't run since 1978 when his brother was killed in a bike accident, since then my friends bike has sat in a garage. so about thirty years have past and he wants it running again.

so far I have rebuilt both the carbs, and cleaned the tank, and replaced the ignition switch guts since he lost the key.

anyway, I hooked the battery up today, and it blows the fuse right away?

not sure were to start on this problem, also I was wondering if someone can give me a basic run down on the wiring like what the four different wires are on the key switch.

thanks a million, I hope to get this thing going for him, and I would like to ride it.

terminal 1=brown/blue=12v from battery

terminal 2=white=general "ignition on " power (ignition light+brake light)

terminal 3= brown/green=running lights or emergency parked

terminal 4=blue/yellow=head light power

hey thanks,,



next question, what is the rectifer for, behind the battery box?

The rectifier is 4 diodes and changes alternating current into direct current.
Basically it is like 4 check valves but for electricity.

the center connector is negative out,
the mounting stud is positive ground,
and the two side terminals go the the green/yellow and green/white that come from the alternator stator. either wire to either terminal is OK.

Thanks again,

I'm trying to narrow down what is causing the fuse to blow as soon as I put it in?

Go through the bike and disconnect every electrical device.
ignition circuits, rectifier, zener, lights, brake lights at the switches, blue capacitor, Then start reconnecting til it blows or trouble shoot looking for a short to ground with an ohm meter (with battery disconnected).

>Go through the bike and disconnect every electrical device.
>ignition circuits, rectifier, zener, lights, brake lights at
>the switches, blue capacitor, Then start reconnecting til it
>blows or trouble shoot looking for a short to ground with an
>ohm meter (with battery disconnected).


I will give it a shot tommorrow, Hope all goes well.

also just to be sure the fuse is the right one,

what size does it take?

15amp slo blow max it would probably run on 10amp slowblow.
A fast blow may blow as soon as you plug into the battery, since the blue capacitor will attempt to charge and act as a momentary short.

the box of fuses that was in the tool pouch, were sfe 14, not sure what amp they are or if they are fast are slow blow.

now I was wondering if I can just eliminate the glass fuse and wire in a 15 amp automotive plastic style fuse.


also, I pulled the whole harness out yesterday and was wondering, could I test the harness, by hooking the battery up and ground it to a piece of metal, or what would be a good way.

its starting to get to the point I think I should just make a new harness, after looking a the crappy connectors that were used, every thing just pulled apart to easy, and really didn't have good contact.

I need to find a wiring Diagram, and figure out what half this stuff is.

thanks again.