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Author Topic: Up in smoke!  (Read 1421 times)

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Offline XN

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Up in smoke!
« on: September 04, 2009, 02:35:29 AM »
My wiring harness on my K8 went up in smoke  >:( Its beyond repair. How different is the 73-75 wiring harness from the 78? I'm thinking of going with the partsnmore harness. I don't mind having to change a few connectors but if the color coding is all different and such I may just have to build my own....

Also what are you guys using for a replacement starter relay? I'm guessing mine is fried. Figure I will have to replace that along with the regulator/rectifier, fusebox and????

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02 Yamaha V-star 650
02 Honda VTX 1800

Offline GoatBaSS

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Re: Up in smoke!
« Reply #1 on: September 04, 2009, 05:11:40 AM »
Go slow. The 73 - 75 are different as I recall since the fuse count was upped from one to three. After the 72 for sure. Find out where the fry is and check to see if everything is secure. Test before you pull. I am sorry for your loss but you will soon have a masters in 78 electrics.
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Offline tlbranth

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Re: Up in smoke!
« Reply #2 on: September 04, 2009, 08:49:43 AM »
Isn't the point of fuses to prevent your harness from going up in smoke? Are you sure it's not just the part in front of the fuses?
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Offline HedNut

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Re: Up in smoke!
« Reply #3 on: September 04, 2009, 09:47:39 AM »
From the looks of my K8 fried wiring...the burn victim was all ground wires...so it didn't go near the fuses. (although it took down more than half the other wires)  But that's just from me taking a quick look-over.

 This is a great thread...because I need one too...and am on the verge of tackling a complete rewire myself...with only 4 colours..ahah
« Last Edit: September 04, 2009, 09:49:20 AM by HedNut »
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Offline TwoTired

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Re: Up in smoke!
« Reply #4 on: September 04, 2009, 11:01:43 AM »
Quote from: HedNut on September 04, 2009, 09:47:39 AM
From the looks of my K8 fried wiring...the burn victim was all ground wires...so it didn't go near the fuses. (although it took down more than half the other wires)  But that's just from me taking a quick look-over.

Next time someone gets near your bike with jumper cables, make sure they connect them the right way.
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Lloyd... (SOHC4 #11 Original Mail List)
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Offline tlbranth

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Re: Up in smoke!
« Reply #5 on: September 04, 2009, 12:45:56 PM »
But still, something hot touched the ground wiring and if it was post-fuse, it should've blown the fuse. What a bummer. Seems like if we pooled together, we could get a roll of each wire color and divvy it up so's everyone interested could put a decent harness together.
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Offline HedNut

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Re: Up in smoke!
« Reply #6 on: September 04, 2009, 01:08:26 PM »
Ooooo... that'd be a nifty idea! How many different rolls of wire would we need to go original.  It'd be neat if I had the resources (a butt load of different coloured wires...and money)...I'd tackle a Modern harness for our old 2 wheeler's.  And mass produce them...but not really.
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Offline XN

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Re: Up in smoke!
« Reply #7 on: September 04, 2009, 02:38:29 PM »
Yea I thought the same about the fuse... I have not had time to really dig into it yet. This past winter I had it all apart and cleaned all the connections and grounding spots so  ???
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Offline TwoTired

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Re: Up in smoke!
« Reply #8 on: September 04, 2009, 05:11:00 PM »
Quote from: tlbranth on September 04, 2009, 12:45:56 PM
But still, something hot touched the ground wiring and if it was post-fuse, it should've blown the fuse.

No sir.  The charging system is not fused.  All other electrical load except the starter motor are fused, though.
The alternator diodes  block current flow from battery to alternator when the correct polarity is applied.  Reverse the polarity on the diodes and they goes into full conduction, appearing as a direct shot across the battery terminals.  The alternator looks like a huge load, drawing very high currents.  The wires simply overheat, melting their own insulation and any wire insulation of wires running next to them.  The fuses never see these currents.
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline tlbranth

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Re: Up in smoke!
« Reply #9 on: September 05, 2009, 09:06:49 AM »
Dang
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Offline XN

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Re: Up in smoke!
« Reply #10 on: September 07, 2009, 10:48:41 PM »
Quote from: TwoTired on September 04, 2009, 05:11:00 PM
Quote from: tlbranth on September 04, 2009, 12:45:56 PM
But still, something hot touched the ground wiring and if it was post-fuse, it should've blown the fuse.

No sir.  The charging system is not fused.  All other electrical load except the starter motor are fused, though.
The alternator diodes  block current flow from battery to alternator when the correct polarity is applied.  Reverse the polarity on the diodes and they goes into full conduction, appearing as a direct shot across the battery terminals.  The alternator looks like a huge load, drawing very high currents.  The wires simply overheat, melting their own insulation and any wire insulation of wires running next to them.  The fuses never see these currents.

Boy you nailed it! It was just the alternator wires after the connection into the main harness all the wires up to the rectifier and to the start relay.
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Offline Hush

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Re: Up in smoke!
« Reply #11 on: September 08, 2009, 01:11:38 AM »
I bought wire from an auto electrical shop and rebuilt my own last year, wasn't hard and cleaned up a lot of my wiring faults, shame I couldn't get exactly the same bullet connectors.
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Offline Toxic

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Re: Up in smoke!
« Reply #12 on: September 08, 2009, 07:16:54 AM »
Since this is related to the OP's original question I'll ask.

If my motor is a 76 will the partsandmore harnes (73 - 75) work?

I don't mind figuring out some of the minor issues like switch gear etc. but I need to know the main stuff like the engine, charging system, reg/rect are going to be OK.

I don't have the skills to re-wire everything.

Thanks in advance
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