Ideas on why wiring melted?

[spreeinkc]

Was working on friends scooter. His kick starter jacked up and wouldn't work anymore so I took it off and installed a regular cover and had him buy a battery. I noticed he didn't have the key and wires were jumed so he'd have lights. Well now that it's electric start only I installed a switch on said jumped wire. Hooked everything up tried switch worked great so tried starting it and it fired right up. He came and got it, drove it home (10 miles) drove it to work the next morning (5 miles) then when trYing to leave work it wouldn't start. I go and pick it up and founder the small red fused wire melted and get ground wire melted though not as bad as red one. Weird part is it was fused and the fuse and everything melted!? Wondering if anyone has had this happen?

[mousewheels]

1) Jumpering Battery voltage to the headlight creates an electrical fault, with a high current path through the Stator coil. That change should be removed.

2) The fuse will protect the wires from melting, double check the correct size fuse was installed. Should be 7 amp for a Spree.

The wire gauge of the Green wire ground and Red wire is about 16 and will not melt if 7A is drawn.

-- Wire diagram markup

Current_path_when_battery_is_jumpered_to_power_headlight.JPG (80.16 KiB) Viewed 3580 times

[spreeinkc]

Didn't jump it for the headlight. It comes on anytime it's running regardless if the key is on. It's jumped at the ignition to send power to everything else besides the headlight (electric start, horn, tail/brake lights, turn signals, etc...). What's odd is it was already like that all I did was put a switch in the middle of the jumper wire so it wouldn't drain the battery. (before when it had a kick start it didn't matter because the battery wouldn't hold a charge and could still start it) So I'm confused as to why now all of a sudden the wires melted and even more so why the fuse didn't blow. It was bigger than a 7amp fuse (not sure what size because it's melted now) but I would think it would blow either way if it got hot enough to melt the whole fuse and wire all the way down the harness down under the floorboard as well as the ground wire for the battery. I don't think it has anything to do with jumping the switch because it does the same thing as turning the key would so I'm just trying to figure out whats going on with it. I'm going to have to replace the harness and don't want it to happen again...

[Meatball]

How good are you at reading wiring diagrams and measuring resistance with a multimeter? To truly diagnose your electrical gremlin you need to test test test! The service manual has resistance measurements for virtually every component and connection(except CDI). Just a matter of poking the probes in the rights places and reading the screen, then compare results with the service manual to see if its within the acceptable range.

For me, this method revealed a bad rectifier on one spree and an open loop on another. Its really the only definitive way to determine an electrical issue.

I also suggest you buy a functioning ignition and a new battery along with the new wiring harness. Mickey Mouse wiring is always a gamble.

[mousewheels]

Sorry - I took the part of jumpering to get lights to mean putting the battery onto the headlight.

It takes a lot of current to melt the wire insulation. I put a section of a Spree harness (yellow wire in pic below) to the max of my bench supply (20 amps) and it was barely warm to the touch.

Edit: Add - Point is - the fused wire will not melt if the proper or even a 20A fuse is substituted. Get back to OEM fuse and worry no more

Honda_Wire_20A_markup.jpg (223.85 KiB) Viewed 3547 times