Coil Mod for bikes WITHOUT points

[AK82kz440]

A much simpler coil mod for bikes without points, found at THE KAWASAKI TWIN OWNERS FORUM :: View topic - Ah, the sweet taste of success (coil mod)
write up by Greg “DALPILOT”
Illustration by Mike “thxone” Hood

If your bike has points you WILL need the relay to do the coil mod. The point and condenser ignition systems may (randomly) leave the points in the closed position when you shut off the engine. If you did a direct wire from coil to battery you would end up draining the battery when that happens.

The Mod:
You don't need the relay! I did the mod about a week ago and it does indeed make a noticeable difference. The coil on the bike is not connected to ground, and draws NO current, when the engine is not running. Normally, one end of the coil's primary winding, and the electronic ignition unit are connected to the battery through both the ignition switch and the kill switch. The other end of the primary winding is connected to ground via a transistor in the electronic ignition unit and is switched on and off at a rate determined by the engine rpm. Only when the transistor is turned on during off/on cycling during engine operation is there current drawn from the battery by the coil. You can verify this for yourself by removing the lower wire (red/yellow) from the bottom of the front end of the coil and measuring the resistance from that coil terminal to ground when the engine is off. It won't matter if you have the ignition key on either as long as the engine is off. The resultant, infinite (not really, but huge) resistance reading is proof that no significant current would be drawn even with a direct connection to the battery, when the engine is not running.

The mod, as I have done, it takes advantage of this fact to eliminate the relay: Pull off the red/yellow wire from the bottom terminal on the front end of the coil. Re-connect the coil terminal to a fairly large guage wire (#12 or #14) and connect the other end directly to the positive side of the battery. The easiest place to do that is the HOT side of the starter solenoid. Yes, you should use an inline fuse to protect things in case of a short. That's it, you're done.

When you make this mod, power is supplied directly to the coil without having to pass through the ignition switch, kill switch, connectors, and long thin wires. The kill switch still works the same because the electronic ignition unit still gets its power through the ignition and kill switches. Killing power to the ignition unit, turns off the coil switching transistor, and shuts off current to the coil even though the hot end of the coil is still connected to the battery. The engine immediately shuts down.

I've done this mod to my bike and it works great. It's probably the easiest mod you can make that will really make a noticeable difference. Thanks to whomever first came up with it.

The diagram:

[meanie4me]

Nice. Thanks for the write-up.

[AK82kz440]

I didn't write it up just copied and pasted! but your welcome.

[b-parker]

will this mod work on a 84 zn1100

[AK82kz440]

Originally Posted by b-parker

will this mod work on a 84 zn1100

As long as it doesn't have points it will work; providing better power to the coils and there by providing better spark to the plugs. Age will cause resistance in the wires, this coil mod replaced the aged wire with fresh wire!
Charlie

[b-parker]

great i will try it. my bike has two coils so i don,t know if that will make a difference or not

[rstnick]

For a bike with two coils just split the power feed to supply power to both coils.

In this diagram of the "WG Coil Mod", you can see how both coils are fed.
This coil mod uses a relay (found at an auto parts supplier) to do the same thing as posted above.

[AK82kz440]

Originally Posted by rstnick

For a bike with two coils just split the power feed to supply power to both coils.

In this diagram of the "WG Coil Mod", you can see how both coils are fed.
This coil mod uses a relay (found at an auto parts supplier) to do the same thing as posted above.

That mod works but is much more difficult than it needs to be for a bike with out points. For a bike with points the relay is a must. For a bike without points you can do the following:



I have tried both mods and they both work exceptionally well getting an increased power supply to the coil(s). They both provide new wire that doesn't have the resistance built up over the years but believe me if your bike doesn't have points it is a lot easier to run 1 wire from the "+" post on the starter relay to the coil than to run 4 wires to differing areas.

[rstnick]

Will the above mod still allow the Kill Switch to work?

[AK82kz440]

The kill switch still works the same because the electronic ignition unit still gets its power through the ignition and kill switches. Killing power to the ignition unit, turns off the coil switching transistor, and shuts off current to the coil even though the hot end of the coil is still connected to the battery. The engine immediately shuts down.