'79 KZ650C Misses/Backfires (cont.)
- Hayward
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'79 KZ650C Misses/Backfires (cont.)
21 Jun 2009 23:08
I've cleaned the(Mikuni)carbs and have run into another issue. On the rim of the bowl inside, there is a clip holding a ball bearing and a round brass piece. What purpose does this have ? I'm asking because I found that one carb was missing the clip and bearing. Patton had made me aware of petcock difference with the vacuum hose disconnected at the #1 intake and plugged:
BTW, the petcock seems to be a vacuum type(on,res,pri). I now have to figure out why and what else has been plugged. Could this cause or be part of my original problem ? The carbs did not seem to be that dirty.
BTW, the petcock seems to be a vacuum type(on,res,pri). I now have to figure out why and what else has been plugged. Could this cause or be part of my original problem ? The carbs did not seem to be that dirty.
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- Hayward
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Re: '79 KZ650C Misses/Backfires (cont.)
22 Jun 2009 11:19
I was hoping to get some answers here. I am not sure I'm ready to replace the carbs. back on the bike. The previous owner had disconnected the vacuum @ #1 intake and plugged but did not change petcock and vac line still connected to #4. Should I try and restore to original setup?
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- timebomb33
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Re: '79 KZ650C Misses/Backfires (cont.)
22 Jun 2009 11:39
can you please put a picture of what your talking about or even a parts schematic up it may or may not be needed.
1973 z1 2-1974z1-a,2-1975z1-b dragbikes1015cc+1393cc, 1977kz1000,1978kz1000,1981kz1000j, 1997 zx-11, 2000 z12r,1428turbo nitrous pro-mod and a shit load of parts thats all for now leader sask.,CANADA
I THINK MY POWERBAND BROKE
I THINK MY POWERBAND BROKE
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- Hayward
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Re: '79 KZ650C Misses/Backfires (cont.)
22 Jun 2009 12:38
I'm sorry ! I have been trying to copy and paste diagrams and images to this reply and obviously don't know how.
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- Hayward
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Re: '79 KZ650C Misses/Backfires (cont.)
22 Jun 2009 13:04 - 22 Jun 2009 13:08
kzrider.com/index.php?option=com_kunena&...d=3&id=289519#290487
I copied a link here, if that helps. Notice smaller hoses teeing off #1 & #4 to center hose going to front of engine.
I copied a link here, if that helps. Notice smaller hoses teeing off #1 & #4 to center hose going to front of engine.
Last edit: 22 Jun 2009 13:08 by Hayward. Reason: add info
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- Bluemeanie
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Re: '79 KZ650C Misses/Backfires (cont.)
23 Jun 2009 06:38 - 23 Jun 2009 06:39
The link you provided is for the smog system. Most guys remove and throw it away, especially when it stops working. On the front valve cover just run a hose (3/4"?) from side to side. Plug off the vacuum nipples and your set.
Here is what your talking about? It's part of the the pump circuit on "pumper" carbs. Lean jetting required an accelerator pump system. This was the one way check valve.
Here is a vacuum diagram (Thanks Patton) for you showing what you need to know?
Here is what your talking about? It's part of the the pump circuit on "pumper" carbs. Lean jetting required an accelerator pump system. This was the one way check valve.
Here is a vacuum diagram (Thanks Patton) for you showing what you need to know?
1980 KZ650F1, Bought new out the door for $2,162.98!
Last edit: 23 Jun 2009 06:39 by Bluemeanie.
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- Hayward
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Re: '79 KZ650C Misses/Backfires (cont.)
23 Jun 2009 10:21
Thanks Bluemeanie ! Now, do I need another type petcock ? What had me baffled about this is the PO only capped off one small vac line on #1 intake and everything else was normal. My plugs indicate a rich mixture now - black and smutty dry.
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- Bluemeanie
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Re: '79 KZ650C Misses/Backfires (cont.)
23 Jun 2009 12:04
If your carbs have the nipple for the vacuum petcock you can just run that. It's nice not having to remember to turn off the gas. You can if you want, cap off that nipple and run a regular petcock. As far as your sooty plugs go you really need to check out
WG's coil mod
. Most people here have done it with great results. About an hours time and maybe $20 will make a big differance. It can in many cases eliminate sooty plugs. Good read, easy fix.

1980 KZ650F1, Bought new out the door for $2,162.98!
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- Hayward
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Re: '79 KZ650C Misses/Backfires (cont.)
23 Jun 2009 12:32
Thanks, I'll just cap off everything but the petcock line and use it for now ... I've developed another problem trying to fix another. Now it's not firing.?. The last thing I checked and set was points. Using a feeler gauge and ohm meter, I thought I had it. The battery was too weak (or so I thought again) to crank and check timing with a light so I charged overnight and this morning started over. I cranked and it ran on choke for about 5 sec. a few times. When it died, it was instant. What in the world could I have done just adjusting points to have caused this problem. I've checked wiring for opens and shorts, also tested coils ( 3 ohms pri., 23 sec.)
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- Hayward
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Re: '79 KZ650C Misses/Backfires (cont.)
23 Jun 2009 16:01
I am lost for next moves. Out of frustration, I pulled the condenser off and according to test, they fail- no arc. I don't know if that would cause it to not fire. I even swapped the primary wires on the coils and it made no difference in the firing ...2&3 points arc but not 1&4. Any suggestions ?
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- Bluemeanie
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Re: '79 KZ650C Misses/Backfires (cont.)
24 Jun 2009 05:53
Someone else is going to have to help you here, I'm not an electrical guy. But...... If you have about $125 floating around you should get a
Dyna "S"
electronic ignition. Best thing I EVER did! Bike fires up so fast and of course it's a set it and forget it.

1980 KZ650F1, Bought new out the door for $2,162.98!
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- Hayward
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Re: '79 KZ650C Misses/Backfires (cont.)
24 Jun 2009 16:22
Thanks anyway, Bluemeanie, this bike belongs to my brother(who is even less of a mechanic than I) and I'll let him in on this latest misadventure. Hope he goes for the Dyna "S". If not , I still need guidance.
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