Author Topic: Yep...electrical questions  (Read 728 times)

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Offline Kinch

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Yep...electrical questions
« on: May 05, 2009, 02:09:40 PM »
I'm learning on the fly with electrical so bear with me.

I had to replace the coils on my 1975 CB750 K5, the points ignition system was replaced by an older Dyna III by the previous owner.

I picked up a set of coils off of a 1979 CB750 but as the Dyna needs at least 3 ohms of resistance and the 79 coils tested at 2.7 ohms I picked up a nifty 1 ohm resistor plate from Hondaman.

I hooked it all up and the bike showed great spark and fired up on all cylinders but then died and I noticed that a fuse had blown. Now this isn't one of the fuses in the fuse-box but one that the previous owner wired in himself and it holds a 20-amp glass fuse.

I've looked all though the bike and haven't found any bad connections or grounds yet although the obvious is that there is a green ground wire sticking out from under the seat (not the main ground connected under the seat but a side one) that has a blade connector on it but isn't attached to anything and I can't find anything that it should attach to. (rigged fuse and disconnected ground wire pictured below)

A couple questions:
With the Dyna ignition and the lower resistance that should only affect the connection in between the coils and the spark-plugs right? I'm going to update the fuse box when I get a chance but that shouldn't be affected by the lower resistance I would imagine.

Also, does anyone know where that ground wire goes and if there doesn't appear to be anywhere to connect it should I just attach a female blade connector and ground it to a good spot on the bike?

« Last Edit: May 05, 2009, 02:13:27 PM by Kinch »
1975 CB750 K5
1980 GS850L

Offline GammaFlat

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Re: Yep...electrical questions
« Reply #1 on: May 05, 2009, 02:30:16 PM »
I can't answer all of your questions but I'll take a stab at a few.  The green wire on the right is kind of a spare ground for your flasher unit.  Don't worry about it.  Most of us have a dangling green wire :)

It looks like the guy did put his own fuse in.  20 amps is a bunch but glass fuses can get old and croak "under their specification".  Replace it with a brand new 15 and see if it blows again. 

Like others on the forum, I have replaced my fuse holder with blades:

K6
K7 
Suzuki GN400 - Ignition fixed!
03 KLR650 - Doesn't do anything very well but.. well.. does everything.

Offline Kinch

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Re: Yep...electrical questions
« Reply #2 on: May 05, 2009, 03:37:48 PM »
Thanks.

Yeah, put a new 15 in and it blew when I turned the key on.
1975 CB750 K5
1980 GS850L