'82 Kawasaki LTD-KZ750 Won't Start

Hello,
Recently acquired an '82 Kawasaki LTD - KZ750 and cannot get it to run. I've worked on quite a few bikes in my lifetime and I am stumped on this one.
Bought it from a guy who said it ran a few years ago and then quit and it had no spark.
Steps I've done so far.
1. Thorough power washing, cleaning and inspecting.
2. Did a preliminary check of the wiring, no power to starter solenoid.
3. Found the start button contacts as the culprit, cleaned, starter now cranks.
4. Cleaned lots of connector contacts for the igniter, rectifier, etc.
5. Checked for spark, all cylinders have spark, might be sort of weak, hard to tell.
6. Pulled the carbs for a cleaning and inspection, overall not to bad considering what I've run into in the past.
7. Installed the carbs without airbox, as a test, thinking it would fire right up. Then if I needed to adjust float levels, etc, carbs easy to pull off, etc. Nope, wouldn't hit a lick.
8. Did all my usual tricks, spraying starter fluid at carb inlets, chock, no choke, starter fluid spray holding throttle open, no luck, nothing.
9. Started all the electrical component specification checks. 
a. Ignition primary, and secondary, all within ohm spec.
b. Pulse coil(s) within spec
c. Igniter ohm check with analog ohm meter. All within spec except Blk to Blk/Yellow and GR to Blk/Yellow spec calls for 200 - 500 ohms, mine come in at around 70 ohms. Overall I was pretty pleased with the overall check.
d. Voltage check at the coil primary terminals, ok at 12V
10. Compression testing next. No.1 = 105psi, No.2 = 105psi, No.3 = 90, No.4 = 100 (No.3 a little suspect but engine should fire and run)
11. Thinking timing issue, pulled the valve cover for a quick inspection. At TDC the CAM lobe position alignments to the top of the cylinder head look to be ok from what I found on the internet doing some research.

I'm thinking it must be the igniter so I bought a used one off ebay this morning, a gamble but I've got to get to the bottom of it. Also ordered a spark tester as I have in the past always used the "ground the plug to the top of the engine" method. Research on this board indicated it's bad idea.
So if the bike is getting spark can the igniter still be the problem? The plug wires are old and brittle but it should at least fire or try to run due to it having spark. Usually if this is the case a bike will run crappy on one or two cylinders and sputter around etc. This beast just won't hit a lick.
Note: Using the battery out of my riding lawn mower which is pretty close to the battery spec for the bike. Starter cranks it over good so I don't think that's an issue. I've done this quite a bit in the past on other project bikes without any problems.  I would like to get the bike to fire up before I purchase a new one.

What do you guys think? I might be overlooking something, I just don't know.
The bike is really decent looking and in pretty good condition. It's one of the black ones, bought one of these brand new when I was in my 20's. Saw this one on craiglist and had to have it!
I attached a few pics so you can have a look at the project. Not shown is the seat which is in fair shape.

Thanks,
Randy
 

Nice bike!

Fuel, compression and spark are the required components, which you have... but they have to occur in the correct sequence and at exactly the required time...

Check that the timing rotor (advancer mechanim)  has returned to its proper position, that is to say, against its stop, fully anti-clockwise. Make sure it can rotate clockwise (under spring tension) about 30 degrees and then back, freely.

It may be stuck in the full "advanced" position: the springs could have failed , or the shaft needs lube.

It is almost impossible to start an engine with fully advanced spark. (unless of course you can spin it at 1000rpm or more)

Open the right hand side crankshaft cover to check this.

In any event, its worthwhile spraying some lube onto those components, regularly.

H.

Do not try to rotate the crankshaft using the 13mm hex-head bolt.
Use a 17mm socket on the bigger nut!
Also, just be aware that if you rotate the crankshaft anti-clockwise... you will engage the starter clutch and spin the starter motor backwards... this is normal.

Also, your pulse coil ohm check at 70 ohms seems low. Should be above 450 ohms. I have had a couple go bad. (Hard to find good used pulse coils)
Many fail by breaking connection inside the moulded plastic, or partially  shorting out causing low ohm reading) 

I suspect your carbs are still plugged. Some of the passages particularly for the pilot circuit are very small and plug easily. Click on the Articles tab above, select Service Manuals and download the one for Gpz750. It covers your model and has and excellent carb chapter.

When i bought my 750 years ago i had to clean carbs 3 time before getting them right. You have to remove the jets and poke through with a #1 guitar string or strong nylon brush bristle. You pilot jet is under the brown stained plugs. Dont lose these. Pull the  pilot jet and clean. You should be able to see daylight through it. You should be able to squirt carb cleaner in the pilot hole a see it come out the pilot bypass . Manual will help identify. Use eye protection ! No kidding.
take off carb top and gently check for tears or holes in the diaphragm.

you can jump from a car battery as long as car engine not running.

i think it should start on full choke without the airbox but may not run without the box & filter and with choke off.

check choke operates

good luck

 

I have an 81 KZ750 LTD, if you need a pulse coil I have one that is currently collecting dust as I swapped to electronic ignition with a DYNA. If you need it then PM me and we can work something out. Using the spark tester should tell you how strong the spark is, I would still check timing, if you can find the manual on this website it will show you exactly how to set the timing on these bikes. Easy enough procedure, means it’s also easy enough to screw up.

I'd verify that the right spark plugs are firing at the right time.
Trace the wiring from the pickup-to the igniter-to the coil-to the spark plugs.
The starting fluid should have fired off the bike if the spark was correct.
 

According to my really old manual, compression seems little low. Have you checked the valve clearance? Maybe they're just hang open a tiny bit.

 

I actually thought of this yesterday and checked the advancer, it moves freely and snaps back so it's seems to be working correctly.

A follow up on the spark issue.
I received the spark tester yesterday and I believe the spark is just to weak. It's a yellowish to orangish color, pretty sure it needs to be blue/white.

@Jr - All jets are clean, first thing I usually check clean when I pull carbs apart.

wrote:

@Jr - All jets are clean, first thing I usually check clean when I pull carbs apart.

Not only the jets must be clean, the brass pilot jet tube #40 and needle jet holder tube #62 has tiny air mixture ports that could have been clogged.

 
 
 

@ Scirocco  
I'll pull the carbs and have another look.  I didn't pull the needle just holders when I had it apart so it will be worth while to have a look.

Another update 
I received the igniter I bought off ebay today and ran a resistance check on it to compare it to the one that I was thinking was bad. The readings matched the original one pretty much on the money, very little difference. 
I went ahead and installed it to give it go, about the same, it did fire and try to start one time not sure how or why but it a least gives me hope
I ran a couple high resistance checks on the positive feeds to ground thinking maybe some sort of tiny grounding was going on. Didn't pick up anything in the megohm range.
The starter does seem to drag and growl a little so I measured the voltage drop as it was cranking. The voltage was dropping to 10.75 Volt during cranking so maybe the starter is the issue. Anyone out there know what the approx. specification (voltage drop) is during cranking? The battery I'm using for my testing has 14AH rating and CCA of 190 and is less than a year old so it should be fine.
Next step is to pull the starter and perform a bench test on it to see if it has the same voltage drop as when it's in the bike. Might do a disassembly and inspection.