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Discussion Starter #1
What's up guys! I've been putting an 84 vt700c "bobber project" back together. Bought it for 300 off a guy and I've been doing my best to get it back on the road

So here's my question. I've got spark in the front two plugs. But not in the back. I've replaced the coils and the spark units. I'm pretty sure my wiring is good. But I'm still new to motorcycle electrical systems. Any help advice or fixes to this problem that anyone has run into would be greatly appreciated!
 

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84 VT500C retro bobber
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A "bobber project" someone else started? Those are always fun, like doing a puzzle with missing pieces and two or three peices that dont belong thrown in. Most common electrical problems I encountered turned out to be bad grounds or connections.
 

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1983 Honda vt750 Shadow
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Get a 12 volt test light and when cranking compare the signal on one coil (negative side )trigger wire to the other. The front coil should be blue and the rear coil is Yellow. When the engine cranks the signal should blink as the ignition unit is grounding the coil to fire the plugs. The rear one probably won't blink.

Also test the pulse generators for resistances = approx 450-550 ohms.

And here is what has been a weird fix for some guys.
The 1984 has a 3rd spark unit (called #2) in line with the other two.
Some guys have disconnected it and reconnected the harness without it, and then they get spark. Runs fine without it.
Crazy but true.
 

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Discussion Starter #4
Thanks guys! I've been reading a lot on here. So I did disconnect the "3rd" spark unit. I'm pretty sure my connections are good. Now grounding? Does the tachometer have a ground/wire setup that is needed to complete the circuit?
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Discussion Starter #5
Get a 12 volt test light and when cranking compare the signal on one coil (negative side )trigger wire to the other. The front coil should be blue and the rear coil is Yellow. When the engine cranks the signal should blink as the ignition unit is grounding the coil to fire the plugs. The rear one probably won't blink.

Also test the pulse generators for resistances = approx 450-550 ohms.

And here is what has been a weird fix for some guys.
The 1984 has a 3rd spark unit (called #2) in line with the other two.
Some guys have disconnected it and reconnected the harness without it, and then they get spark. Runs fine without it.
Crazy but true.
Also I have a problem with getting things backwards. I have the yellow wire to the ignition coil on the left side (front cylinder firing)
Does this mean the blue should be on the right (front cylinder coil) and the yellow on the left (back cylinder)?
 

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Discussion Starter #6
A "bobber project" someone else started? Those are always fun, like doing a puzzle with missing pieces and two or three peices that dont belong thrown in. Most common electrical problems I encountered turned out to be bad grounds or connections.
And yes you are absolutely correct! Definitely a fun irritating at times but great puzzle! Can't wait to get it on the road.

I've already had to un-sieze the engine and buy quite a few missing broken or just completely wrong parts!
 

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1983 Honda vt750 Shadow
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The tach and other gauges and bulbs have GREEN ground wires.
All the solid green wires on these bikes are grounds.
 

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