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Author Topic: No power to the 78 550K  (Read 1490 times)

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Offline 5youngs

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No power to the 78 550K
« on: August 05, 2005, 10:43:50 AM »
We got the bike running the other night and when we went to put the headlight back on it appears to not have any juice going up from the battery to the key now.

I checked the battery and it is fine. All the fuses (5 of them) appear to be fine.

Does anyone know if there is a fuseable link on this bike?

Any ideas on where to start looking?

Thanks, Mark
« Last Edit: August 05, 2005, 10:55:10 AM by 5youngs »
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Offline TwoTired

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Re: No power to the 78 550K
« Reply #1 on: August 05, 2005, 11:00:27 AM »
Don't rely on a visual check of the fuses.  Measure each side of them with a Voltmeter.  Contact oxidation and current flow heating can melt them.

If you have a bad fuse,  Check out this thread.
http://www.sohc4.us/forums/index.php?topic=2206.0

The two fuses at each end are spare positions for fuse storage.
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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 5youngs

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Re: No power to the 78 550K
« Reply #2 on: August 05, 2005, 11:17:42 AM »
Thanks again, TwoTired. I will do this and let you know.

Thanks
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Offline egar

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Re: No power to the 78 550K
« Reply #3 on: August 05, 2005, 02:04:45 PM »
I had the same thing happen to me on my 78 550k. The main fuse looked OK, but when I removed it and held it against the light, it was popped. Used one of the spares and it was fine again.
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sohc4

'04 ST1300, '70 cb750KO

Offline 5youngs

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Re: No power to the 78 550K
« Reply #4 on: August 08, 2005, 06:53:25 AM »
I found out what was wrong.

I took the fuse box off and cleaned the fuses and holders with some 320 sandpaper. After i was done with that I took the back off the fuse box and found one of the leads to the main fuse had the solder malted off of it. After re-soldering the lead to the back of the fuse holder viola!, it works fine!

Now I have to fine tune the bike. I am thinking about new plug wires and playing with the carbs a bit more.

Thanks again to TwoTired for the help!!!!

Mark
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Offline TwoTired

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Re: No power to the 78 550K
« Reply #5 on: August 08, 2005, 09:52:35 AM »
You're welcome.
Always nice to hear success stories.

Just a note.  Cleaning the contacts restores proper operation.  But, does not address future oxidation.  I use a spray called De-oxit, that attacks the oxidation and delays it from forming on the contact surfaces.

Cheers,
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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 5youngs

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Re: No power to the 78 550K
« Reply #6 on: August 08, 2005, 11:22:19 AM »
I did spray some sort of contact cleaner on the points as well. I am not sure what kind it is right now.

Thanks
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