no spark after 750 swap into 700

I have just put a 1982 kz750 engine into a 1984 kz700 that was laid down and had the ignition ground off the engine but remarkably little other damage. The problem is i have no spark while cranking the engine, either with the button or by directly putting power to the starter bypassing the relay. I am using the stock pickups that were in the 750 motor, as the ones in the 700 were completely destroyed. I can run a flat tip screwdriver through the pickup and get a strong spark though. Thought someone here might have some good ideas on where to go next.

No spark? Or spark at the wrong time?

It's possible the advancer rotor is 180 degrees out, or the black and green wires got swapped, or the spark plug wires are on the wrong cylinders.

The right hand coil should get the black wire and should connect to cylinders 1 and 4.

The left hand coil should get the green wire and should connect to cylinders 2 and 3.

When the 1 and 4 pistons are near TDC, the rotor should point toward the rear pickup which has the black and blue wires on it.

When the 2 and 3 pistons are near TDC, the rotor should point toward the front pickup which has the red and yellow wires on it.


EDIT:
I can't find a 1982 KZ 750 that has electronic-advance. They all had mechanical-advance.

The 1984 KZ700A1 (and ZN700A1) used the electronic-advance ignition system.
It is not compatible with mechanical-advance pickups.
You will need a mechanical-advance igniter (from many KZ models and years), or get a pickup and rotor from a KZ700.

No spark, period without spoofing the pickup. The ignition rotor is fixed, not a spring loaded type advancer. Besides, would not make any difference as there is no spark when the rotor passes the pickup. Are there any known problems with the rotor? I am a professional mechanic since 1989, and work on motorcycles often. I do have a bit of a clue, have tested the coil resistances, pickup resistance, have new plugs, new battery and a booster to maintain voltage. My biggest complication is i do not have a wiring diagram, or a testing chart for the 700. Plus my computer just died a couple of days ago, doing this on my phone. Any help is appreciated.

I am not totally sure of the new engine year, as i got it out of someones garage, not a complete bike. 1982 is as close to a year as i could find, might be 83

Do the pickups look like the type that were in the 700?
(If it were using the mechanical-advance rotor, the module would only get a single pulse as the rotor passes the pickups. The electronic-advance rotor produces a split-pulse, or two pulses separated by a ramp. That's why the two rotors look so different. Your screwdriver test probably produces multiple pulses to produce a spark.)

I can post a diagram on how to wire the module to bypass the safety diode logic (kills ignition under certain conditions). I'll have to get to my other computer to dig it up.

This is a ZX550 diagram, but the module should wire the same.

I took another look when i got out out in the shop, and i was wrong. The advancer is mechanical after all, sorry. Posted a pic here. Thanks for the excellent diagram, that makes sense now. I can even read it on my phone :woohoo: thanks for the hei ignitor diagram too, built one 3 years ago and it worked very well. Do you think the hei module igniter would work in this instance if i built another?

Will the 700's coils work with it or do i need to use the coils from the 750, not sure of the stock 700 coils rated primary resistance

Yes, the HEI modules should work fine with the 700 coils and 750 motor. My signature has the link to that page.

Save the 700 ignitor box though. That is not an easily replaceable item $$.

Ok, I have built an hei ignitor module for the bike. Have good spark on both coils. But will only run on 1-4. Checked timing after fixing advancer and 1-4 is right on the $. 2-3 is about 15 degrees retarded i cannot seem to figure out any way to adjust the pickups individually. Any help would be appreciated much.

Possibly, you could slot the plate the pickup coils mount on, to change the timing. If you have access to a milling machine with a rotary table, I'd think this would be the cleaner way to do it, but careful filling with a rat tail might do it too(not as neat).

wargoth wrote: Ok, I have built an hei ignitor module for the bike. Have good spark on both coils. But will only run on 1-4. Checked timing after fixing advancer and 1-4 is right on the $. 2-3 is about 15 degrees retarded i cannot seem to figure out any way to adjust the pickups individually. Any help would be appreciated much.

Double check the pickup wiring. If you swap pickup wires, it may still spark, but with the timing delay as you describe.

It can also be a result of a pickup magnet being flipped the wrong way, if you've had it apart recently.

Details on testing pickup and magnet polarity are here:
home.comcast.net/~loudgpz/GPZweb/Ignitio.../PickupAndRotor.html

Do the voltmeter test for checking polarity and make sure the voltage is about the same for both pickups when moving the screwdriver the same speed.

SOLVED!! Thanks very much! It seems that i got the 2-3 reluctor coil electrical polarity reversed. Lou, you are an electrical genius :laugh: too many color changes in the wire and me trying to hurry. Runs very well now.

Excellent! Glad it worked.