Wire Fire!!!!

I just had a couple of wires spontaneously combust! Wiring/Electrical work is not my strong point, so maybe someone can lend me some advice.
When I got my bike, it was in the process of being converted to a stunt bike, and had no ignition switch. I have been using a toggle switch just to run/tune the thing, and have had no problems until today. I was running it above idle, and all of the sudden the positive ignition wire started smoking and burnt off all of the insulation. What could cause this??? I also have my fan wired to come on with the ignition if that helps explain anything... What can I do to stop this from happening? Will switching to a larger positive ignition wire help(I think it is 14ga now)?

 

WELL, I will say that a wire melting is due to over heating of the circuit because of high resistance (too small of wire for load). This maybe your case. You can run it off a relay, should be better off.

 

I would say you have a dead short check you switch thats most likely the problam.

 

Please excuse my ignorance, but what is a relay? And a dead short?

 

Dude, are you serious your other post says your an experienced mechanic, well my friend electrical work is part of wrenching. 14ga is definetly to small for a starter circiut, fan should run off of a seperate ignition hot not along w/ the starter (both electrical motors, both prone to shorts that cause high amperage draws.

OK....
Relay is a little black(generally) box approx 1"x1"x1" basically it allows you to control a high amperage circiut via a low amperage circiut. There are generally 5 terminals on a relay terminals are usually labeled w/ #'s 30 which you would install a battery or ign. hot wire to(hvy gauge) 87a generally not used this is the off or at rest switch position 87 is the switched voltage out
85 would be your low amp power in 86 would be ground. so when you energize term #85 with your low amp voltage say from your ign switch it in turn energizes a pull in coil switching voltage output from 87A(off) to 87 which in this scenario would go to your starter( this saves switches as relays can handle a lot more load). A dead short would indicate that the power supply is finding an alternate ground before it reaches the intended appliance(will blow fuses) or the ground circiut for the intended appliance is open( in other words the wire is broke, corroded severely<will also blow fuses as it creates heat/high resistance in the circiut>, or really loose)

Link to a Bosch relay diagram & basic circiut illustrations

http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm

 

I know, I know. I'm quite embarassed about my lack of electrical knowledge, I guess I never really "got" it.
What I don't understand is why I am burning up wires, because I am using the stock wiring, just with a toggle in place of the keyed switch. Would the addition of the fan to the switch be enough to cause my problem by itself? I was planning to put the fan on a seperate circuit eventually...
Also, it was not the hot-wire to the starter that burnt up, but the stock positive wire to the ignition switch.
Thanks!

 

If your toggle switch is not rated for enough amps it will short out and melt the wires... I've never had this problem with a bike, but I had a 86 firebird that I put a cheap toggle switch on to control the electric fans... Same thing happened and the wire melted...

Try a bigger switch...

 

Generally when you start melting stuff you have a dead short/short to ground(I've started a $100,000 truck on fire by accidently grounding out the alternator hot wire, it took less than 10 seconds to melt 20' of 2.0 battery cable & burst into flames & about 6 hours to replace it all & fix the "progressive damage") Check for shorts to ground, check for poor grounds(loose, broken wires either visably or internally in wire casing, corrosion) If all that looks ok the starter could be shorted internally or possibly the fan motor; are you going directly to the fan motor or thru the temp sensor? if thru the temp sensor you can pretty much rule out the fan motor.

 

I am running power directly to the fan motor. I think that my toggle may have contacted on the frame near the bars when the bike was running...

 

That would do it