2 and 3 intermittently dying

As far as the electrical goes, before proceeding I would fix the voltage issue - 9.2V at the coils means they're only getting 75 % of what they're supposed to.

Did you also check the voltage going to the Dyna-S (red wire) - if you have a 25% voltage drop to the coils you likely have a voltage drop to the Dyna-S too.

If the problem persists after fixing the voltage issue, at least you have eliminated an electrical cause and can move on to compression, float height and carb sync as already suggested.

As for the stock coils, as long as they are in good working condition they will work just fine with the Dyna-S - quoting the instruction sheet: "It (the Dyna-S) was designed for use with stock or other coils, or combination of coils that have at least three ohms primary resistance."

Well I just got off the phone with dyna and the guy said the stock 5 ohm coils might cause slight performance issues such as a higher idle but its unlikely that is my problem. He said overall the bike should still run fine, so I guess I need to keep looking.

I'm a bit confused as to why the bike is smoking.. its not smoking a ton, but it is noticeable and you can smell gas in the air. Its running better today for whatever reason.. I finally got it to stay running without the choke on. I also noticed the strangest thing.. if the bike is on its kickstand leaning to the left it will slowly die out, but if i lean it over to the right while it is slowly dying it will rev back up. Something is up with the carbs I think.

I still cant get it to stay running with idle set lower than 2k. And it still makes lots of faint popping sounds from the muffler.

I do plan on cutting the bad wires to the coils out this weekend when my new connectors come in the mail. I will check the dyna S voltage right now.

I couldnt figure out how to measure the dyna S voltage without doing some damage to the wires but I sprayed the headers with water and confirmed that cylinder 2 is alive and well but cylinder 3 is totally dead. I shut it off and pulled the #3 plug, here it is:

Its hard to tell but the center electrode is moist so it doesnt seem to be a fuel problem.. and since I know #3 has spark, the only thing left that I can think of is compression.

PUT 2 plug wire on three and see if three is now working......if it is then plug wire is bad.

4TheKZ1000 wrote: PUT 2 plug wire on three and see if three is now working......if it is then plug wire is bad.

Will I have to swap the wire connections at the coil or can i just take the 2 wire off the 2 plug and put it on the 3 plug? Its odd because when I first got the bike running the #3 cylinder was definitely working.. and i havent really dont much that could damage it.

who8myrice wrote:

4TheKZ1000 wrote: PUT 2 plug wire on three and see if three is now working......if it is then plug wire is bad.

Will I have to swap the wire connections at the coil or can i just take the 2 wire off the 2 plug and put it on the 3 plug? Its odd because when I first got the bike running the #3 cylinder was definitely working.. and i havent really dont much that could damage it.

They both fire off the same coil so all you have to do is move the wires.

who8myrice wrote: Well I just got off the phone with dyna and the guy said the stock 5 ohm coils might cause slight performance issues such as a higher idle but its unlikely that is my problem. He said overall the bike should still run fine, so I guess I need to keep looking.

I'm a bit confused as to why the bike is smoking.. its not smoking a ton, but it is noticeable and you can smell gas in the air. Its running better today for whatever reason.. I finally got it to stay running without the choke on. I also noticed the strangest thing.. if the bike is on its kickstand leaning to the left it will slowly die out, but if i lean it over to the right while it is slowly dying it will rev back up. Something is up with the carbs I think.

I still cant get it to stay running with idle set lower than 2k. And it still makes lots of faint popping sounds from the muffler.

I do plan on cutting the bad wires to the coils out this weekend when my new connectors come in the mail. I will check the dyna S voltage right now.[/quote]

You didn't buy those plug wire connectors did you, where you splice to the old wire, and install a new wire from the splice to the plug?
If you did, you should have just bought new coils. Those plug wire splices are not what you want to put money into, just a band-aid.
Didi you ever get your compression tester in the mail? Before you go spending to much, please be sure your compression is serviceable.

Motor Head wrote:

who8myrice wrote: Well I just got off the phone with dyna and the guy said the stock 5 ohm coils might cause slight performance issues such as a higher idle but its unlikely that is my problem. He said overall the bike should still run fine, so I guess I need to keep looking.

I'm a bit confused as to why the bike is smoking.. its not smoking a ton, but it is noticeable and you can smell gas in the air. Its running better today for whatever reason.. I finally got it to stay running without the choke on. I also noticed the strangest thing.. if the bike is on its kickstand leaning to the left it will slowly die out, but if i lean it over to the right while it is slowly dying it will rev back up. Something is up with the carbs I think.

I still cant get it to stay running with idle set lower than 2k. And it still makes lots of faint popping sounds from the muffler.

I do plan on cutting the bad wires to the coils out this weekend when my new connectors come in the mail. I will check the dyna S voltage right now.[/quote]

You didn't buy those plug wire connectors did you, where you splice to the old wire, and install a new wire from the splice to the plug?
If you did, you should have just bought new coils. Those plug wire splices are not what you want to put money into, just a band-aid.
Didi you ever get your compression tester in the mail? Before you go spending to much, please be sure your compression is serviceable.

No I was referring to the wires going from the coil to the wiring harness... it loses a full 1.3V between those short wires. The compression tester should be here tomorrow so ill let you guys know how that goes.

Can you explain what you measured to find where you have the voltage drop? Which short wires are you replacing? Pictures would show it, can you post up a picture?

who8myrice wrote: ... 1979 KZ650, dyna s ignition, 4-1 vance and hines exhaust with pod filters, mikuni VM24SS carbs with accelerator pump

Could create a signature that includes information about the bike.

Including information about bike year and model is helpful to viewers and usually elicits better responses.
It's easy to put the information in your signature where it shows in all posted messages, past and future.

And may be changed whenever and as often as desired.

If wanting a signature showing information about the bike in posted messages, it's easy to do.
Here's how:




Good Fortune!

Thanks Patton!

Well I tested all 4 cylinders and the lowest one still had 165 psi so I can rule out a compression problem, which is good. However, the strangest thing happened before I ran the test. I was warming it up for a few minutes when i decided to spray the headers with water again.. get this.. #2, 3, and 4 were firing just fine, and now #1 was totally dead. WHAT!? I've never had a problem with #1

After the compression test #1 was back and #3 was dead again.. go figure.

That being said, I think I found my problem.. I believe I have a pretty severe vacuum leak. I noticed the vacuum port plug on carb #3 seemed loose so i tightened it up a bit.. suddenly it would happily idle at 1500 rpm with no choke. At this point cylinder 3 seemed to be running maybe 50-75% of the time, but the bike only bogged a little bit when I pulled the #3 plug off whereas it stalled completely when I pulled the #1 plug, and it still didnt evaporate water on the header as quickly as 1 2 and 4, so I know there is still a problem. I sprayed some gumout on both sides of the carbs while it was idling and the engine bogged down SEVERELY each time. So Im thinking maybe my carb boots are shot, but I inspected them thoroughly last time and found no leaks so I dont know. Either way it looks like im pulling the carbs again.

This would also explain the severe backfiring.. granted I have no idea why its still smoking so much. Maybe I overfilled the oil..? my sight glass is pretty fogged up..

If the bike has the original coils & spark plug wires, replace them. The intermittent firing is fairly common w poor electrical connections or faulty electrical components. The coils can test fine cold, but they can be faulty under high voltage.