My 1981 GPz550 has lately been cutting out and dying while riding. I believe the problem is electrical because its just like turning the kill switch to Off. No sputtering, no backfiring, no bucking just all 4 cylinders die instantly. Throttle position does not appear to be contributing factor because the GPz has died when rolling the throttle On/ Off or at steady throttle. When stranded on the side of the road, the GPz550 restarts immediately every time. I suspect but have no evidence the ignition switch or the On/Off switch which are original items are the culprit.
I have done some initial troubleshooting. I have eliminated the fuse box as the source because I swapped out and replaced the fuse box from a newer KZ550 parts bike and had the same problem. The coils are Dyna Green 3.0. When I remove the tank I will check the coil resistance and electrical connections. My GPz has a Dyna S ignition. I do not know if Dyna S ignitions have a history of intermittent failures? My experience with Dyna S has been positive. I have a Dyna S on a UJM 1000 4 and its been going for 35+ years. When I restored this GPz, I removed the wiring harness and replaced any wires which were burnt (few) or cosmetically crappy . The the wiring harness was in very good condition. I believe the the Dyna S has a red wire that taps into coil "+". Not sure how to troubleshoot the Dyna S either except check connections? I am biased in believing the Dyna S either works or it does not. The fact the GPz restarts suggests intermittent electrical connection. If the previous statement is true then the ignition and kill switch are suspect and have to be tested and verified. Not sure how to test the ignition and kill switch while in the garage other than measuring resistance and pulling on wires hoping to see infinity.
I am pretty sure others have had similar issues with their KZ/GPz's etc. so looking forward to hearing I am not alone.
The Dyna S does draw more current in the ignition circuit than the bike came with originally so it could be heating up a connection and causing it to become intermeittent.
The kill switch would be my first suspect (after the fuse box) and the ignition switch would be very close behind.
A good test would be to simply run a wire from the battery to the coils and Dyna S. You could put a switch on that wire and then you would have a temporary, secondary power source for the ignition. If this also results in stalling, then the Dyna S becomes a more likely suspect.
You will also want to make sure the engine has a good connection to the battery ground as that is the ground the Dyna S uses to operate correctly.
And of course, if you are using those scotch-lock press-on connectors to power the Dyna S, get rid of them and use real connectors or solder.
Is there a kickstand or clutch switch? If so, try jumpering them out. You could also jumper out the kill switch and the ignition switch (one at a time). If after all this jumpering, the problem persists, I like the idea posted above of running a battery wire directly to the coils.
You say that you have a Dyna 'S' ignition and 3 ohm Dyna coils fitted but in your pics the coils are grey Dyna 2.2 ohms ?
Unless you have switched to 3 ohm since the pics were taken you should fit them asap as the 2.2's resistance is too low for the Dyna 'S'.
I was mistaken about "the coils are Dyna Green 3.0". I was thinking about my UJM 1000 which has a Dyna S & green coils. My GPz550 which I purchased in 2014 came with Dyna S and grey Dyna 2.2 coils installed. Best guess my GPz550 had not run since 1993-1994. I think the Dyna S is a DS-2 model which was originally for KZ650.
Interesting side bar I just purchased a set of Ebay Dyna 2.2 ohm coils that were removed from a running 81 GPz550. Here is the video of that 81 GPz550 with set of grey Dyna 2.2 coils installed. I did not check if a Dyna S Ignition was installed though.
Took a short ride yesterday afternoon on my GPz550 and it ran without dying. First to say that does not mean its fixed
Whatever coils it came with if it has a Dyna 'S' fitted it must have 3 to 5 ohm coils to match.
The 2.2's are wrong .
They are ok for the Dyna 2000 or stock Kwak electronic ign but not the 'S' regardless of the model application.
There are some online shops wrongly selling the Dyna'S' and 2,2 ohm coils as a package .
The coils will overheat badly and the whole set up won't last long..
You're right. Thanks for spotting the grey Dyna 2.2 ohm coils and what I overlooked. I am searching for Green Dyna 3.0 coils and will sell the Dyna 2.2 coils. I contacted Dynatek because I was curious what could explain the longevity of the Dyna 2.2 coils. Guesstimating the coils were installed in the late 1980s. The PO parked the bike circa 1993-1994. Here is the Dynatek response.
Thank you for contacting us regarding your Dynatek DS2-2 ignition and coils.
Other than the Honda CB550 and smaller Honda 4 cylinder engines, all Japanese 4 cylinder applications would indeed use either 3.0 ohm to 5.0 ohm coils.
This is required due to the Dyna-S's lack of an active dwell control system and a lower than 3.0 ohm coil will generally be overcharged and damage to the coils from overheating as well as possible Dyna-S damage may occur.
With this all said and done, some 1980 to 1982 Kawasaki models did come from the factory with a part called a Ballast Resister, which installed in the switched 12 volt power supply wire to the coils. This resister effectively lowered current to each coil and were rated at between 1.2 to 1.5 ohms. My guess is (and you will need a factory wiring diagram to verify) that your model GPZ incorporated this resister. So, as you have 2.2 ohm Dyna coils and lets say a 1.2 ohm ballast resister installed, this actually would equate into the Dyna-S only believing you have coils rated at 3.4 ohms and this is very likely why it is running after all these years.
I might suggest at this point running what you have and you likely will be fine. Should a coil or DS fail, I would then perhaps consider making the change.
If you need any further assistance, please let me know.
PS: I reviewed the 81 KZ550 D1 wiring diagram and I do not see a ballast resistor. If I recall from R5 experience ballast resistor are physically big items