KZ440 Ltd Weak Spark and Faulty Electronics

Have been working on this bike for months and it is getting worse - can't even start it now.
Ignoring all the carb work (should be perfect now), have good and equal compression, valve clearances ok, need some advice on the elctronic components. At the front end the spark is weak - holding plug against cylinder it is yellow. Bought ignition coil spark tester and set to 5mm - spark blue but weak and very intermittent and irregular (varied gap up to 10mm and lost it).
Been through book with multi -meter (not Kawasaki -= they say it makes some difference but not sure how much on the resistance?) - got following results:
COIL
Secondary should be between 10.4-15.6. Got 11.27
Primary should be between 1.8-2.8. Got 2.4
No readings between Primary and Secondary.
Obviously this doesn't tell you what's happening when HT going through it.

PICKUP COIL
Join leads should be 360-540..Got 428
No reading between leads.

IGNITION WIRING CHECK
Black to earth should be 0.5-1.0V. Got 0.84V
Blue to earth should be 0.8-3.0V. Got 0.88V

Battery V = 14.2 (just charged)
YR to earth. Got 13.91V
YB to earth. Got 13.91V

RESISTANCE OF IC IGNITER
Y/R (+) to Bk/Y(-) should be 0.3 - 1.2. Got 0.35
Bk/Y(+) to Y/R(-) should be 1 - 3. Got 1.7
Y/Bu(+) to Bk/Y(-) should be 200-700. Got 200
Bk/Y (+) to Y/Bu(-) should be infinity. Got 6

Bu (+) to Bk(-) should be 30 - 130. Got 114
Bk (+) to Bu(-) should be 20 - 70. Got 115

Any other home tests I can do?

COIL appears ok but is original (has brand new lead, caps & plugs on).
PICKUP ok - but was wet through when opened up. Sprayed with WD40.
WIRING CHECK seems ok, but volts to earth on Pickup blue just in.
IC IGNITER - got a reading when there should be infinity and last two tests giving same reading.

Any thoughts on where to next. New coil is easy but other parts are expensive and second hand!
Have been through electrics at back of bike and made good - lots of faults and cowboys in there. Cleaned cut off in clutch. Not looked in right handlebar yet.

Great job of posting test results... very thorough.

When testing for spark with dual-output coils, you have to make sure both plug wires have a path to ground (or each other). I just want to make sure when you check for spark on one plug wire, the other is grounded or very close to ground.

If the spark is there, but weak, the bike will usually still start and idle, but won't rev under load or under large throttle openings.

The spark should easily jump 1/2 inch (12mm) on one plug wire as long as the other plug wire is grounded. It won't usually jump a 1/2 inch on both plug wires simultaneously very reliably, and doing that can cause permanent damage (degradation) to the coil or the igniter.

If it is intermittent, I would check the plug wire leads first, that is if they are removable. Sometimes a carbon build up at the coil-wire connection can cause the symptoms you are experiencing.

I will have to review the color codes of the 440 igniter to check what you reported on the YB wire.
EDIT: So I thought you meant Yellow/Black, but now I see I think you mean Yellow/Blue. That voltage reading is normal.
It will pulse briefly (very briefly) near 0v immediately before sparking.

Generally speaking, if the igniter is bad, you can probably use one from an inline-four Kz, or you could try to make one if you can find the right type of 4-pin HEI module. Details for that here:
s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html

Replacement coils should be pretty easy to get. You want something rated nominally about 2.3 ohms. (Actual measurement changes with use and temp etc.)

With your intermittent problems (and your tests), I would put the likelihood of problems in the following order:
-Plug wire connections and resistor caps (if equipped).
-Voltage feeding the coil
-Coil itself
-Pickup coil
-Igniter

Brilliant - thanks for response.
Had already replaced HT leads and caps.

Yes - meant yellow/blue on V test.

Took coil and igniter off bike today and retested. Resistance in coil primary and secondary is within spec.

Sparyed with electrical cleaner and got some different numbers off igniter today:
Y/R (+) to Bk/Y(-) should be 0.3 - 1.2k. Got 7.1M
Bk/Y(+) to Y/R(-) should be 1 - 3k. Got 91k
Y/Blu(+) to Bk/Y(-) should be 200 - 700. Got 0.7M and climbing
Bk/Y (+) to Y/Blu(-) should be infinity. Got 0.7M

Have ordered replacement igniter (£70) - can return if not needed.

Difficult to track down an appropriate new coil - has Toyo Denso zc006-TR12V. Seems to have been used on lots of bikes. 10cm space between mounting bolts - any recommended alternative manufacturers / or appropriate alternatives from other models?

Hopefully nearly there. Have tracked down a second hand pickup coil from same supplier should I need that too.

Probably going about it wrong way round from your suggestion, but ingiter seems all over the place (tho I've read modern multimeters aren't compatible/reliable!)

With the spark, left one plug in the bike and connected the other cap to the tester. So if I understand right, should have earthed the one in the bike. If so, should that be the -tive ht lead while testing the +tive one?

Thanks again for your time.

I'm not sure what spark tester you are using. I usually just use some non-conducting object to hold the plug away from the head.

You can leave the other plug in, but it's easier on the starter motor to pull both plugs out. You can just lay that plug on the head. You should see both plugs spark simultaneously when testing. The polarity of the high tension shouldn't matter.

Hi - I'm using Laser 5655 ignition coil spark tester.
Just laying plugs on head gave a weak yellow spark. In the tester it was blue and very inconsistent (missing) and dropped off after about 5mm. It was firing up a couple of weekends ago but couldn't keep it running then nothing last weekend. Fixed lots of wiring over the weeks and so it sound like something is dying, accelerated with increased electrical flow. If its not the coil, at least will have a reliable spare for when the 40 year old one does give in - and perhaps it will give a better spark anyway.

Hopefully the replacement igniter will be here early in the week and I'll let you know what happens. Have also contacted an electrical store in Brighton for advice on the coil. For similar bikes price is around £35-45. I'm avoiding the £20 ones on EBAY. Found one for the bike in Holland, but they wanted £150 - and I'm not certain it would fit the mounts!

Some say the ignition coil is the weak link in the Kawasaki electronic ignition. A coil can test fine cold, but still be bad. Some guys heat it w a heat gun prior to testing. Another way is to ride the motorcycle at highway speeds, then stop & feel the coil. press hard w your fingers & don't get burned by the valve cover. The coil should be warm, not hot. My were very hot, so I got the green Dyna 3.0 ohm coils from Z1Enterprises.com, which solved a high-speed miss. A couple of other times the problem was the battery >> the motorcycle needs a good, fully charged battery to run right. I test mine regularly w a VC97 digital multimeter, use a Ctek US 0.8 smart charger & do a load test periodically.

Put a new battery on before Christmas when problems first started - haven mentioned yet that previous owner put small carbs on from a 400 and made up massive gap around engine and airbox mounts with tape!
New Dyna 2.4 ohm coil on the way. Hopefully up and running tomorrow.

New coil and replacement igniter arrived. Need to do some work on coil fittings.

Igniter has same number on it, but mine has an additional brown and white earth! Assume this makes an importance difference - but why the difference?
Also ran the Multimeter over it and got even more strange results - it comes from a reliable supplier, so assuming that only the original Kawasaki meter measures accurately! Hoping therefore that the old igniter is ok.

Will report back when its all on the bike, but any advice re earth wire appreciated.

Later twins, or at least the later Kz750 twin which uses virtually the same ignition system (except the advancer), had an additional wire for a kickstand lockout. This would kill the bike if you tried to drive off with the kickstand down. Normally you just ground the wire to disable the system and the igniter should run like normal.

I don't have a 440 diagram showing this wire. I'll try to look in the filebase.

My info for Kz750 twins shows this extra wire to be pink. And it shows the extra wire attached by itself rather than going through the normal connector for the igniter. Is your brown/white wire outside the normal connector?

Yes, on the original igniter the earth wire is separate from the connectors.
The replacement one doesn't have this earth.
The 440 doesn't seem to have a kickstand cutout switch but it does have one on the clutch lever.
Also, when we started working on the bike the earth went straight to the frame although the original connection is still available.