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1978 cx500
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Discussion Starter · #1 ·
Hi all,

Ive recently been working on a 1978 cx500 and have run into some electrical problems. It’s still in the early stages right now and was hoping to get it to at least fire up this weekend. Currently in my bike I don’t have much plugged in besides the reg/rec (ricks li-ion) starter solenoid, battery ignition switch, fuse box, kill switch and ignitech ignition The harness itself is a bit of a work in the process due to my inexperience and the PO’s disorganization but when I put juice to it, it wouldn’t turn over and blew my main fuse. The bike would turn over however if I contacted both ends of the starter solenoid. Little bit lost as I think there might be a short somewhere or maybe I’m missing a ground? Any help or guidance is greatly appreciated

-brad
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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11,059 Posts
If it's blowing your main fuse, there's a short somewhere. Does it happen as soon as your connect the battery, or only after you turn the key switch?
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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11,059 Posts
Is it the original key switch? The similar looking assembly for the later TI machines is more readily available, and a lot of eBay sellers don't make the distinction.
If the key switch is good, the fault will be somewhere down stream. You'll need a wiring diagram, a multimeter, and maybe a test light.
 

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1978 cx500
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5 Posts
Discussion Starter · #5 ·
Is it the original key switch? The similar looking assembly for the later TI machines is more readily available, and a lot of eBay sellers don't make the distinction.
If the key switch is good, the fault will be somewhere down stream. You'll need a wiring diagram, a multimeter, and maybe a test light.
I believe it is the original key switch, not 100% sure. I did try to hot wire it with black to red and brown to brown white if I remember correctly and it made a slight humming noise. It didn’t turn over but it also didn’t blow the fuse as well so I might have to try that again. I think I will have to pull out the multi meter though.
 

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'84 CX650E that is evolving into a GL500
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17,291 Posts
Re hot wiring: Don't worry about the brown and brown white for now, they are only for the tail light/parking light circuit and have nothing to do with starting the engine. Connecting the red (power from main fuse) and the black (switched power) together should power it up.
Also, your '78 should have a black/white wire to the keyswitch to kill the ignition when you turn it off so make sure it isn't connected to anything while testing.

Re correct keyswitch: Bikes in this family came with either Capacitor Discharge Ignition (CDI) or Transistor amplifier Ignition (TI). With CDI a wire from the ignition is shorted to ground to kill the spark but with TI the power to the ignition circuit is interrupted, which mans that the keyswitch for one won't work with the other. I can never remember which one has 5 terminals in the connector and which has 6 (hopefully someone who knows will tell us) but if you use the wrong one it will blow the main fuse as soon as the key is turned on. If the bike was someone else's project before you got it there's a good possibility that they bought the wrong replacement.

BTW: Don't forget to add your location and your bike's model and model year to your profile like I asked you to when you first posted (see Forum Settings link in my signature).
 

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CDI has 6 terminals, TI has 5. But there's also ringers from other Honda models. I have a 6 pin switch here that doesn't work with CXs.

The contact plate retainer on this one is white, not black. No idea of its source.
 
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