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View Full Version : 73 fx wiring probs.



Crawdadbobb
06-25-2017, 9:12 AM
Yo. I rebuilt this bike and it had a mess of problems , don't know how previous rider didn't die. That's a story for another day. Anyway, I replaced a lot of ratty wires, and cleaned up useless connections that weren't even working. I'm at one of those hands in the air moments that so many of us get to when you are wrenching on this stuff day and night. I went to ground out solenoid to start bike (kick and electric) and I got a buzz/shock through the clutch handle, I have NO wires going to the clutch side or throttle side. What the hell is grounding out? Any ideas where to start chasing a short with that description.?#brainfried, no drugs.

tzienlee
06-25-2017, 9:53 AM
Two things come to mind,
1) does the clutch cable come close to or touch one of the Plug leads?... if it does you might be getting a High Tension jolt from there shorting out down the cable.
2) if the transmission or starter isn't grounded (direct to the Battery in the case of the starter) it could be trying to ground the starter via the clutch cable but I wouldn't have thought a 12v ground would have given you a shock,

Crawdadbobb
06-25-2017, 9:59 AM
I don't have the trans, battery bracket in "screwed in" but it is on the battery tray bolts. I thought it would be grounded out, and yes the clutch cable it a little close to the plug wires. I'll move them outta the way and bolt in bracket all the way and see if that does it. Thanks

Crawdadbobb
06-26-2017, 6:19 AM
Ok. Put bracket on, rerouted clutch cable. Still getting shock but it's way less than half of first jolt.

Tattooo
06-26-2017, 7:11 AM
Is it killing your battery??? Or have you got that far???

farmall
06-26-2017, 9:22 AM
If you get shocked when grabbing anything hanging off the handlebars that means they are hot, which means a hot wire to something on them is shorting to ground but the resistance of the neck bearing "ground connection" (not a cable, but the return path of the resulting circuit) is enough for your body to provide a better ground path.

Remove your switch control screws and dangle them in space. Also check for chafed wires. When the bars are no longer hot you are closer to the problem. I'd remove one switch cluster at a time. If there's nothing visually obvious ground one probe of your voltmeter then probe for hot.

The best way to repair 1970s wiring is usually shitcan all of it then do a proper job with bare crimp connectors and heat shrink tubing.

Crawdadbobb
06-26-2017, 2:19 PM
If you get shocked when grabbing anything hanging off the handlebars that means they are hot, which means a hot wire to something on them is shorting to ground but the resistance of the neck bearing "ground connection" (not a cable, but the return path of the resulting circuit) is enough for your body to provide a better ground path.

Remove your switch control screws and dangle them in space. Also check for chafed wires. When the bars are no longer hot you are closer to the problem. I'd remove one switch cluster at a time. If there's nothing visually obvious ground one probe of your voltmeter then probe for hot.

The best way to repair 1970s wiring is usually shitcan all of it then do a proper job with bare crimp connectors and heat shrink tubing.



I do not have any handlebar wiring whatsoever. Only a headlight which is on and working.

farmall
06-26-2017, 6:22 PM
Precisely how do you "ground out" your solenoid??? And by the solenoid do you mean the starter relay solenoid or the solenoid which moves the fork to engage the Bendix?

It should not require you to ground anything to operate, but an application of twelve volts to the small terminal to energize the solenoid.

Some solenoid designs do use two coil terminals and the coil stays hot awaiting a switched ground to operate the solenoid but you'd have to deliberately choose one of those as a starter relay.