Kz 900 coil opinions

I have a '75 KZ 900 and am having trouble with it just up and losing two cylinders. I will be riding down the road and it will just fall on it's nose and you can tell it just lost two cylinders for a couple seconds then fire and run fine. I checked the points and coils and they seemed fine so I started it up and got about 200 feet from the garage and it did it again.
Points looked very good, probably have less than 500 miles on them.
I removed the coils completely from the bike so there was no question on the readings.
The coils metered 3.6 and 3.8 ohms at the primary with the meter at the 200 ohm setting.
The coils metered 12.5 and 12.7 ohms at the secondary with the meter at the 200K ohm setting.
The plug wires can be removed from the coils so I checked the coils secondary with and without the wires and there was virtually no difference in the readings.

Do you folks think the coils are metering OK or ar they bad?
What would you check next?

762shooter wrote: ...'75 KZ 900 ...just up and losing two cylinders. I will be riding down the road and it will just fall on it's nose and you can tell it just lost two cylinders for a couple seconds then fire and run fine. I checked the points and coils and they seemed fine so I started it up and got about 200 feet from the garage and it did it again.
Points looked very good, probably have less than 500 miles on them....
What would you check next?

What would you check next? --
As to the non-combusting cylinders:
Spark quality; plug readings; fuel levels; possibly of too rich pilot circuits.

Good Fortune!

What's the compression on all cylinders? Checked the valve clearances lately? Also inside the sparkplug caps, a 5000 ohm resistor may becomming intermittent(I'd change all 4 caps).

Its been within 500 miles at the most that I checked the compression and valves, I don't remember what the valves were but they were well within spec and the compression was as follows.
#1, 115 psi, 150 after adding a little oil
#2, 100 psi, 125 after adding a little oil
#3, 100 psi, 130 after adding a little oil
#4, 110 psi, 130 after adding a little oil

All the plugs read OK, all were a light brown or tan except #4, it has give me fits with fouling on start up and gets a dark or carbon build up that cleans right off.

This may or may not be related but I'll toss it out there. I checked the air screws and #4 was about one turn out farter than the others so I slowly closed it and about 1/2 turn in from where it was the bike ran better and stopped fouling that plug on startup.

Sorry to sound dumb but how do I check the ohms inside of the caps,from where to where?

Once you've determined the problem, if it's the coils and/or points, I'd suggest going with a Dyna S and the 3.0 ohm coils. It's a very popular upgrade around these parts.

How old are the coils ? Is it time to upgrade to the Dyna ask suggested ?
Fewer ignition problems with new modern electronics and the cost isnt to bad either. Its your time , money, and riding season

To check the resistance of the sparkplug caps, unscrew them from the sparkplug wires, then put the multimeter in the ohms setting(looks like an upside down horseshoe, the symbol for Omega)range of 20K. Put one probe whre the sparkplug would go, and the other probe where the cap screwed into the sparkplug wire. If the caps are any good, you should see resistance.

Now, if you're using an Analog meter(the kind with the moving needle) you'll need to "Zero" the meter by touching the two probes together, adjusting the "Zero" control until the meter indicates zero.

Digital multimeters do not need "Zeroing" as they self adjust in the resistance settings.Before re-installing the sparkplug caps, cut about 1/4" off the ends for a fresh connection.

If you go with new ignition coils, be they made by Accel or Dyna, the primary wires(the small ones) will come really close to the ignition coils mounting hardware causing a potential electrical short, blowing fuses.Some rider replace the metal coil mounting spacers with plastic or nylon ones.

You'll also need to change the primary wiring terminal ends for the type with ring lugs, as what came with your bike has 1/4" push on connections. I'd say 3/16" or #10 hole lugs will work.

I'd cut off the old lugs, and using a wire insulation stripping tool and then a crimping tool, replace the terminals(lugs).

I'd suspect the primary wire sizes are 22-18 gauge, so #10 or 3/16" RED insulated terminals will be what you'll need. Usually stripping back the insulation 3/16", so the conductor is visible inside the terminal before crimping will work.

Wire Termination Insulation & Sizes
Terminal Insulation Color Wire Sizes
RED

---

22-18 gauge wire
BLUE

---

16-14 gauge wire
YELLOW

---

12-10 gauge wire
RED

---

8 Gauge
BLUE

---

6 Gauge
YELLOW

---

4 Gauge

The ring terminal holes comes in many sizes, from #4 up to 1/2" in most cases, it's a matter of finding the tightest fitting hole to fit the fastener for the termination.

American Wire Gauge(AWG) is backwards to what many people think; that is 22 gauge is many times smaller than 10 gauge even though the number is bigger.

Try reversing the coils and see if the problem goes with the coil.

One coil fires 1 & 3 , the other 2 & 4. If youre not losing 1 of those pairs of cyls is not likely the coils. With the motor running if it will, wet your finger and touch the pipes, the cold ones are dead.The cyls number #1 on the left sitting on the bike. Let us know which 2 cyls are dead and we can go from there. You also might want to check the voltage coming to the coils & makes sure its 12 volts. Lots of old swtiches & wiring on 34 year old bikes. Check the wires too as mentioned

mtkawboy, I believe you are mistaken on the coil to cylinder numbers, one coil fires on #1 and #4 cylinders and the other coil fire the #2 and #3 cylinders.
There is a date stamp on the one coil of something in the April '83 range IIRC.
I have had a Dyna-S DS2-1 for 4 or 5 years brand new in the box, I put it on the bike back then and it screwed up in about 20 miles or less and Dyna give me the tough luck blow off. I had a guy that built high performance and drag bikes at the time take a look at it and how it was installed, he said he didn't see any problems and since he was a Dyna dealer/installer he called them and sent it in but it still cost me like 45 bucks to have them fix their junk. Frankly I just left it in the toolbox when it came back because of the trouble I had reinstalling the point ignition when the Dyna failed.
I may have to buy a set of coils and reinstall the Dyna-S.

Ok, should I go with the Dyna green coils?
Should I go with 7 or 8 mm wires and copper core or suppression core?

As soon as I get a chance to borrow a timing light I am going to recheck the timing and point gap but I don't think that is the problem.

BTW, it doesn't miss/cut out long enough for me to pick out which coil is messing up and being that I have a defibrilator in my chest I'm not even supposed to be messing with it, lol.
But we won't tell my wife will we?

:whistle:

Since occurring within 200 feet, cold start go for a short ride until it happens, feel exhaust headers, which two are colder...

Or better yet, with rear wheel raised so as to go through gears if needed, start engine, warm her up... Rev her and there until it happens.... With TIMING LIGHT, check all 4 plug wires, which two are missing strobe effect...?

How old are the condensers...?
Your meter a capacitance measurement mode to measure the condensers...

Plug wires and caps stiff/brittle as well...

I'm with others, Dyna S 3ohm coils (Green), Dyna plug wires w/caps and IE ignition...
Just make sure to Notify Jeff/crew (Z1 Ent) on which advancer unit you have (2 different mounting plate slots).

If nothing else and coils measure out to specifications, insure Vdc at coils is to spec/tight terminations, and feeds from points plate is all good. Not to mention your carb settings are right as well. Carbs sync'd...?

Coil Measurement's should be ~ 30K on the secondary, your short of that in your measurements...