79 GL1000 and 15.3 volts.


Information and questions on GL1000 Goldwings (1975-1979)
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Justmike
Posts: 19
Joined: Tue Jun 21, 2022 5:29 am
Location: Scotland
Motorcycle: 78 GL1000 K3

79 GL1000 and 15.3 volts.

Post by Justmike »



Looking for some help/advice please.
The last couple of days i`ve been helping a friend with his 79 GL1000. He had a blown head gasket so we have been repairing that. He hasn`t had the bike long and has been spending a lot of time doing maintenance on it. After we did the head gasket yesterday he took it for a test ride and the repair has been a success. But there has been a persistant missfire on one cylinder at tickover and clears as the revs go up. On the test run the bike seemed to be fine, and on returning to his garage the engine started missfiring badly and started dying on us.
I then remembered that I had a similar problem on my 78 which turned out to be a faulty rectifier allowing too much voltage to the system. So we set about testing the system. We found the battery was getting 15.3 volts delivered to it at 3,500rpm, but when we tested the battery later, it had enough charge to start the bike but on pushing the starter the voltage dropped to 7 volts.
Today we put in another battery but it wasn`t fully charged allowing us only limited time to test things. We again got 15.3 volts so we laid hands on a spare regulator and tried that with no change. We swapped out the rectifier, again with no change. We tested the stator with engine off and that seems okay. Tomorrow when the battery is fully charged we will fire the engine up and test the stator output.
When my own bike had the rectifier fail I tested my bike with the same regulator and rectifier which we used today and everything was fine, so we are confident those parts are working. Interestingly I am using a rectifier/regulater combined and my own bike only goes up to 14 volts.
i find it strange that after swapping out the regulator and rectifier we are still getting too much voltage. Is there something we are missing that could cause this problem? We have used two test meters to rule out one being faulty. We also tested my bike which I knew was putting out 14 volts and that was the reading we got.
Any help given will be greatly appreciated by my friend, and of course myself.


User avatar
CT1100
Posts: 30
Joined: Mon Jan 20, 2014 8:43 pm
Location: Hartford, Connecticut
Motorcycle: 1983 GL1100I original owner
1985 Cycle Mate CM 1000 trailer
2006 Harley Ultra Classic
1964 Yamaha YA6

Re: 79 GL1000 and 15.3 volts.

Post by CT1100 »

I don’t have any experience with the 1000 but assuming the charging systems are similar to the 1100 your answer may be found in this thread.

viewtopic.php?f=4&t=69596

Chris
Justmike
Posts: 19
Joined: Tue Jun 21, 2022 5:29 am
Location: Scotland
Motorcycle: 78 GL1000 K3

Re: 79 GL1000 and 15.3 volts.

Post by Justmike »

Thanks Chris. I will be heading round there shortly and will look into this mod. I have relays here that we can try, so fingers crossed.

Mike
Justmike
Posts: 19
Joined: Tue Jun 21, 2022 5:29 am
Location: Scotland
Motorcycle: 78 GL1000 K3

Re: 79 GL1000 and 15.3 volts.

Post by Justmike »

Just an update.
We checked the alternator plugs and they`ve been fried, but the actual cable and connectors were fine.
New plugs fitted and some petroleum jelly to lube them up a bit and charging voltage is a solid 14.1 volts. I think that can be looked on as being fixed.
Still a few issues to fix though.
The kill switch isn`t working and on checking the cables we find a scotch lock across the black and b/w wires from the switch to bypass the switch and keep a permanent connection.
On removing the scotch lock the bike would fire and then cut out on releasing the start button. Typical of a failed ballast resistor. But there is no ballast resistor as someone has swapped the coils and removed it. So we put the connector back on and the bike fires up. How weird is that.
Anyway i`m convinced the battery is past its best so my pal has ordered a new one and then we will be refitting a ballast resistor to make the system work as Honda intended.


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