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1977 KZ750 Twin AGAIN!

  • Biquetoast
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  • King Jeremy The Wicked
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28 Dec 2005 19:40 #14950 by Biquetoast
Replied by Biquetoast on topic 1977 KZ750 Twin AGAIN!
I just want to pipe in and remind you that it was running fine before.

I'm not sure why you are now questioning the wiring *design* now.... although I *would* be questioning the quality of the existing old wiring...

Also, since you're fouling plugs, why not check your floats and see if they are stuck or something?

And remember, if both plugs are fouling equally, it could be because the spark is weak because of wiring...

Here's what I would do (actually it's what I DID): Put the Newtronic back together (in fact, I soldered it together because those connectors are kinda flimsy), and do the coil mod. Don't hesitate. And look for bad grounds while you're at it. If you *still* have a problem, then tackle that then...

(1.) '75/'76 KZ400D - Commuter
(2.) '78 KZ750B3 Twin - Commuter
(3.) '78 KZ750B3 Twin - Commuter
(4.) '75 KZ400D - Sold
kz750twins.com

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  • shawntmartin
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29 Dec 2005 12:47 #15070 by shawntmartin
Replied by shawntmartin on topic 1977 KZ750 Twin AGAIN!
No, I'm not questioning the wiring design..I'm just posting pictures to show where I tested the voltage. Mainly, because this is easier to describe with pictures, rather than words alone. I'm testing the voltage because a few people a few posts back and Shaun from Newtronic said it was a good idea. The idea was that maybe the Newtronic box wasn't getting the full voltage from the battery...and I was trying to test that. So I guess this was just my update on their suggestion. The grounds are all fine. The wiring on the bike seems to be in excellent condition and connected securely in all places. The carbs seem fine. The floats are right on and not stuck. They were rebuilt not too long ago...not that it makes a real strong point. Don't know.. I'm tired of getting no where. My next step is just buying a new Accel coil and wires to see what happens. *IF ANYONE HAS A SPARE CARB JUST TO TEST I WOULD SEND YOU A DEPOSIT AND PAY FOR SHIPPING TO AND FROM MY HOUSE BACK TO YOURS.* (...if it is my carb)

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  • Biquetoast
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29 Dec 2005 12:55 #15071 by Biquetoast
Replied by Biquetoast on topic 1977 KZ750 Twin AGAIN!
shawntmartin wrote:

...My next step is just buying a new Accel coil and wires to see what happens...


I think your first step should be the "coil mod". Make sure the coil you have is getting full power!

Heck, you'd prolly have to do the "coil mod" before you got new coils anyway....

(1.) '75/'76 KZ400D - Commuter
(2.) '78 KZ750B3 Twin - Commuter
(3.) '78 KZ750B3 Twin - Commuter
(4.) '75 KZ400D - Sold
kz750twins.com

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29 Dec 2005 13:24 #15077 by loudhvx
Replied by loudhvx on topic 1977 KZ750 Twin AGAIN!
The Newtronic systems act goofy when they get inadequate voltage. Your symptoms sound like a charging system problem to me. It sounds like it ran fine until the battery started to lose charge. Once it falls below a certain amount the Newtronic fails to spark. Letting the battery sit for awhile might let it recover long enough to fire up for a while.

That thick "wire" to the points plate should actually have a few small wires inside of it.

The pictures are a little strange. I need to confirm a few things.

1. The red wire and the black wire definitely go to the coil and nowhere else? (ie, no resistor block attached)

2. That yellow/red wire coming from "somewhere" should be the positive power coming from the ignition/kill switch. It should have the same voltage as the battery when the key is on (measure with the negative meter-probe on the battery's ground terminal). Does it? If not, how much is the difference?

I would prefer to see the blue ground wire soldered to a ground wire (on or near the battery) instead of bolted to the frame.

Post edited by: loudhvx, at: 2005/12/29 16:42

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  • shawntmartin
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30 Dec 2005 08:23 #15206 by shawntmartin
Replied by shawntmartin on topic 1977 KZ750 Twin AGAIN!
I'll check on all of that and post pics tonight.

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02 Jan 2006 22:27 #15771 by ballstix
Replied by ballstix on topic 1977 KZ750 Twin - damn thing.
Sorry I forgot to mention I change the plugs to a hotter plug because I change from a 2-2 to a 2-1 exahuse, I also change the points out and condensor and the problem went away also reset the timing. Good luck.

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