450 Mark 3 ingition wiring

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Paddles
Posts: 6
Joined: Mon Oct 16, 2017 9:35 am

450 Mark 3 ingition wiring

Postby Paddles » Mon Oct 16, 2017 11:22 pm

I'm a new joiner here trying to sort out some electrical issues on my 450 mk 3 (71). It started after a wire (red) from the ignition switch melted and I don't have any current from the white wire from the coil. Its 12 volt with a recently replaced the coil. The wiring has been tampered with over the years too and the diagram in my old manual isn't very clear. Just wondering if anyone has had this issue or maybe has a clearer wiring diagram--especially for what goes on inside the head light cone?
I don't have much experience with the wiring and am running the risk of mucking it up even more if I continue. thanks,

Paddles

Jordan
Posts: 1380
Joined: Fri Dec 24, 2010 11:29 am

Re: 450 Mark 3 ingition wiring

Postby Jordan » Tue Oct 17, 2017 9:30 am

Hello.

Go: www.motoscrubs.com

> TECH

Scroll down to, and click on:

Widecase schematic #1
Widecase schematic #2

for a couple of wiring diagrams.

Good luck.

Jordan
Posts: 1380
Joined: Fri Dec 24, 2010 11:29 am

Re: 450 Mark 3 ingition wiring

Postby Jordan » Tue Oct 17, 2017 12:05 pm

See also: https://docs.google.com/document/d/1zm6 ... 3lvs/edit#
or: https://www.scribd.com/document/6396536 ... le-Wiring# (same good stuff, different source)

"The wiring diagram for the average vehicle is an awful confusion of many wires, all of which seem to be going everywhere."

JimF
Site Admin
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Joined: Fri Oct 23, 2009 2:49 am

Re: 450 Mark 3 ingition wiring

Postby JimF » Tue Oct 17, 2017 9:42 pm

This is a common problem. You have a troublesome electrical problem, but owing to years of different owners making changes and repairs your wiring doesn't seem to match the factory wiring diagram which is hard to make sense of even if you understand wiring diagrams.

I would expect that your decision would be to simply repair what you have.

The wire that burned up carried more amperes than the wire's copper strands could handle. The amperes, amps for short, found an easy path (a circuit) to return to the power source.

The easy path had a very low resistance to the flow of amps. The resistance was so low that too many amps just poured through the wire and burned up the wire.

It could be that the wire's insulation wore through due to being pinched or perhaps abrasion occurred as a side effect of vibration and the copper wire touched the frame or engine or something metal and that provided an un-desired low resistance circuit for the amps to flow. That's commonly referred to as a "short circuit" or a "short".

Another possibility is that a load that the wire is intended to supply amps to has become less resistive owing to an internal failure.

Or it may be that the recently installed coil, if fed by the burned up wire, is too low a resistance but it took some amount of time before the insulation got so hot that it melted.

We could explore that a little further. If you turn on the ignition but don't kick over the engine and get the bike started, the points might by chance come to rest in the closed position. This sends many amps through the coil which would normally interrupted constantly by the engine rotation. But as the engine is not spinning the amps are flowing easily through the coil which is itself just a long length of wire.

The wires in the motorcycle should be able to handle the amps under all possible conditions but maybe whoever chose the 12-volt coil didn't take this worst case scenario into consideration.

Jim

Paddles
Posts: 6
Joined: Mon Oct 16, 2017 9:35 am

Re: 450 Mark 3 ingition wiring

Postby Paddles » Wed Oct 18, 2017 2:35 am

Thanks Jim and Jordan for the quick replies and some new diagram links. I'll work through the ideas you gave and see if I can get my head around the wiring in the light cone a bit better. I already know that's its a long way from the original schematic in my manual with lots of new pieces spliced in. I'll let you know how it goes and thanks again for the help.

Paddles
(450 Mk 3)
Central Queensland

JimF
Site Admin
Posts: 1124
Joined: Fri Oct 23, 2009 2:49 am

Re: 450 Mark 3 ingition wiring

Postby JimF » Wed Oct 18, 2017 2:08 pm

It's a given that you'll replace the burned out wire.

You'll want to put a fuse in series with the wire. In that way, if the problem was not the fault of the wire such that replacing the wire does not constitute the complete repair, the fuse will give out before the wire goes up in smoke and flames.

The fuse will be easier to replace than to keep replacing the wire as you continue to trouble shoot.

Let me know if you don't know what I mean when I say "in series".

Also, we might want to consider if the wire that burned up was too small an AWG for the task as that could have made the wire burn up.

We might also want to decide what size fuse to employ so that it will give its life to save the wire.


Jim

Paddles
Posts: 6
Joined: Mon Oct 16, 2017 9:35 am

Re: 450 Mark 3 ingition wiring

Postby Paddles » Fri Oct 20, 2017 1:07 am

Hi Jim,

It would be fair to assume that I don't really know what you mean if you refer to any electrical troubleshooting.

I'd like to try a fuse in series. The red wire that melted was going to a fuse--the front one of the three--I thought it would have burned out too before the wire (its 15 amp). The wire gauge is another issue--what's recommended? The heavy gauge one was the green (I think earth), the red and white ones lighter.

Another thing is the coding on the 3 pod ignition switch--I can make out a '0'--does the earth wire go there?

The thanks heaps for the info...I hope to try some of these things this weekend. Cheers, P

JimF
Site Admin
Posts: 1124
Joined: Fri Oct 23, 2009 2:49 am

Re: 450 Mark 3 ingition wiring

Postby JimF » Fri Oct 20, 2017 7:47 am

I'm not sure how much help I can be in time for this weekend.

Speaking generally, the electrical ground is not passed through a switch.

A 15 amp fuse will protect a 14 AWG wire from a dead short. That your wire burned means the wire gauge could not handle 15 amps.

The formula for power is simply volts multiplied by amps. You have a 12-volt system. Twelve volts times 15 amps means the wire is fused for 180 watts of power, which I suspect is far above your electrical system's power capability.

More to follow later...

JimF
Site Admin
Posts: 1124
Joined: Fri Oct 23, 2009 2:49 am

Re: 450 Mark 3 ingition wiring

Postby JimF » Fri Oct 20, 2017 1:48 pm

If your electrical system worked well before the wire burned up, it's probably safe or at least a good place to start by using the same gauge wire as the one that burned.

Modern wires imprint the gauge onto the insulation (the sheath.). Chances are your insulation is burned off and you have no clue as to the wire gauge.

You can roughly assess the gauge of the burned up wire by taking a chunk of the wire and comparing the diameter of the copper area to potential replacement wires.

Comparing the diameter of the insulation can be problematic as some wires have thicker insulation.

Another way to check is to use a wire strippers with graduated holes for stripping wires. Find the hole that cuts through the insulation but not the strands and you can read the gauge off the strippers.

Once you have the replacement wire in place, change the fuse to a lesser value. The highest value the fuse should be below the wire's ampacity. The lowest value should be be somewhat above the maximum amperage of all the loads on the wire added together.

Paddles
Posts: 6
Joined: Mon Oct 16, 2017 9:35 am

Re: 450 Mark 3 ingition wiring

Postby Paddles » Mon Oct 23, 2017 1:29 am

Jim...I spent some time on the wiring over the weekend. I replaced the melted wires in the light cone as per your advice and as it didn't wreck any thing else, I haven't added an extra fuse in series. I seem to have current to the ignition switch again. Making some progress was great but there's no head lights or horn. There is rear parking and stop light and some indicator lights. I'm going to read the wiring manual and try to start trouble shooting the individual wires now. Is that the best way forward? Cheers, P


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