After market coil replacement for 1981 KZ1300. This article is based on a series of posts I made on KZRider between June 18th 2005 and July 2nd 2005.
I bought this 1300, my first, two years ago from a fellow in Ohio and had it shipped to Oregon. Iâ€™m not sure of the correct designation but this bike was originally a step between the naked 1300 and the Voyager, which would not actually appear till 1983. It came equipped with a fairing, saddlebags and a trunk, although the latter two were gone by the time I got the bike. My plan was to take it back to be simply a KZ. Along with the bike I also got a separate DG Six into one exhaust system which I installed right after I rebuilt the water pump. I couldnâ€™t bear to reinstall the original system as it was pretty well rusted. In retrospect, that may have been a mistake because, with a new exhaust system, I had no base line against which to judge the bike's state of tune. Sure enough I encountered mixture problems, but before delving into the carburetors I decided to be sure the ignition wasn't at least part of the problem.
1300's are notorious for running hot, hot enough to cook a set of coils shoehorned in behind the radiator between the frame tubes and the valve cover. Stories about broken down ignition coils are common on this bike. One of the symptoms of a weak coil can be reduced secondary voltage, which just might have been what was causing my dirty plugs. Even before I got it running I knew that I didnâ€™t much care for the stock coil location because I very nearly could not get the upper radiator hose back on when I was going through the cooling system. So now I had a mission, I was going to replace the stock coils with aftermarket units and solve the space problem at the same time.
There is a lot of information available for these sixes at www.KZ1300.com. David at KZ1300.com keeps up with new developments and periodically posts updates about the durability and advisability of the some of the modifications his readers come up with. It was there that I read an article that described how to fit a General Motors coil pack for a six cylinder Buick to a Kawasaki 1300. This was the first setup I tried, here's a pic of that installation. I had to mold the bottom of the seat to get enough clearance for the wire caps.
The most attractive part of this modification is how neatly the coil pack fits into the tool tray freeing up that space above the valve cover. Unfortunately, that's the end of the good fit. I made the swap and was pleased to see that my 1300 seemed to like the new coils. However, as I learned more about coils and ignition systems I came to realize that the GM coil pack was a terrible fit at least electronically.
The stock coils read 1.7 ohms and are fitted, in series, with a 200 watt 1.7 ohm ballast resistor for a total primary resistance of 3.4 ohms. That means that half of the power consumed by the ignition system goes up in heat with the other half used to generate the secondary voltage for the spark. No wonder the stock systems broke down easily.
It was only after I had completed the coil pack installation, that I realized that the 2.5 ohms of primary resistance Iâ€™d been shooting for only applied to later 1300â€™s that did not use a ballast resistor. Oh Well! Plans evolve and mine sure were. I should have realized that the 2.5 ohm setup didnâ€™t fit my 81 very well at all. I had checked the GM coil pack and found that it had .8 ohms of primary resistance, once I added the stock 1.7 ohm ballast resistor, I was right there at 2.5 ohms. Unfortunately, this 2.5 ohm setup was even less efficient than the stock coil/ballast resistor setup because I was now dissipating two thirds of the igniterâ€™s output in heat with only one third going to making spark. To make things worse, running with 2.5 ohms instead of the 3.4 ohms, the igniter was designed for, might cause it to fail.
I did a bunch of research looking for aftermarket coils that might be smaller than the stock units or might fit as well in the tool tray as the GM coil pack, no such luck, they're all larger than the stock units. I checked them all Nology, Dyna, Accel and others, all of them are larger than the stock coils. The tech department a Nology told me to look elsewhere as their coils were rated at 3 ohms but depended on an igniter that was current limited which the old Kaws were not. I eventually settled on the Dyna DC1-1 which is a twin output coil rated at 3 ohms. They sell for $155.00 per pair, yes that's right I had to buy four coils to outfit my 1300. The folks at Dyna said that their DC1-1 was the right coil for the job and could take the heat. So, I started over, this time with a set and a half of Dyna 3 ohm coils. While these are larger than the stock coils and not nearly as neat and compact as the GM coil pack, they are almost exactly what the stock igniter wants resistance wise, plus all the primary voltage goes to making spark.
There was no chance of mounting them in the stock location but I was able to mount one where the top coil used to fit and I put the other two back in the tool tray, where I had previously mounted the coil pack.
Not quite a cute as the coil pack but still a lot more serviceable than the stock setup. I made the wires long enough so that I can lift the pair of coils and lay them on the tank to get at the air filter and battery. Here's another pic of the whole setup.
A few more details such as putting all the primary wires in a loom and I'm going to call this modification done. Oh by the way it runs great! Starts right up! Plenty of hot spark and when I need to remove the valve cover I don't have to touch the coils.