coil relay mod for 1100 Kats ?

[mak68]

Anybody ever try this mod on an 1100 Kat ?




I tried searching Katriders and couldn't find anything on it. Either my powers of search-fu are weak or it's not here.

There's an explanation of it I found here:

http://pages.tstar.net/~fergy/writeups/coil_relay_mod.html

Supposedly it delivers a full 12 volts directly to the coils from the battery/starter relay bolt, producing a nice hot spark at the plugs.

The fuse between battery/starter relay bolt and the automotive relay on a Kat may require different amperage too, or does it?

Anything there that might screw up or blow up my Kat?

[SweetLou]

That would be pretty interesting. I don't understand a damn thing there, but I am betting BP could chime in here. If it didn't blow up anything, I would try it out I guess. But would getting a set of aftermarket coils basically do the same thing???

[mak68]

But would getting a set of aftermarket coils basically do the same thing???

I think the purpose of this particular mod is to eliminate voltage drop from the battery to the coils in a stock setup. The power wires that plug into the coils seem to run through the harness, and not directly from the battery to coils. I'm supposing voltage drop can happen if the wires are old/deteriorating, or are part of another circuit that may be faulty/old as well. Even if one has good coils, if the right amount of juice isn't reaching them, spark could be weak.

Voltage drop won't allow the circuit to deliver 12v to the coils, and may result in a weaker spark. A more direct path from battery to coils like in this mod is supposed to address that. That's my take on it from what I've read anyways.

My main concern is if this mod could bake a CDI, or some other delicate piece of circuitry on the bike.

I've got a GS750T that I did this to, and it seems to have worked, but then again, a 750T is not an 1100 Kat..

[loudnlow7484]

It seems like it should work. I never did test the voltage at the coils when I had the bike all apart, but if there is any appreciable loss than it could certainly help. If the loss is very small, though, then it wouldn't be worth the added complexity (one more thing to check if it stops running). Check it out and then let us know how it works.

BTW- We don't have Cdi ignitions. If we did, there would be no constant power source at the coils, so this wouldn't apply. Our ignition systems are of the inductive pickup variety.

[mak68]

Check it out and then let us know how it works.

BTW- We don't have Cdi ignitions. If we did, there would be no constant power source at the coils, so this wouldn't apply. Our ignition systems are of the inductive pickup variety.

Thanks for the info loudnlow. Seems to be the same system as my 750.
I'll give it a go on the weekend and see what happens. I'll post the results with some before and after shots.

[BIGKAT1100]

[DClark]

I wouldn't do it. Good intentions, but...
I measured the voltage going to the coils and it was low, maybe 7. 8 or something like. Don't remember exact number.
My theory is that these bikes have an anemic ignition. This is evidenced by low voltage coming from the ignition module and a very, very small plug gap, especially when you consider the low compression of the motor. I have heard of glowing reports of the Dyna III ignition waking up the bike, that could be due to more power at the plugs.
Anyhow, I have relays on my my headlight and I think the best way to get more power to the coils would be a circuit that disconnects the headlights when started, maybe when the kickstand is down.
The only time I wish I had more power at the plugs is when it is real cold (below freezing).

[suzukiray]

YES!, it DOES work & we have been doing that mod to GSs over @ www.thegsresources.com for years! PLEASE don't coment negatively about something you have NEVER tried! It WORKS!!! PM me if you want the P/N for the relay. Ray.

[Kreylyn]

Wouldn't this bypass the issue with kats not wanting to start with slightly low charged batteries as well as improve cold weather starts?

Krey

[loudnlow7484]

YES!, it DOES work & we have been doing that mod to GSs over @ www.thegsresources.com for years! PLEASE don't coment negatively about something you have NEVER tried! It WORKS!!! PM me if you want the P/N for the relay. Ray.

You don't use a normal 5-pin automotive relay? I would think a standard-issue Bosch 5 pin SPDT relay would work perfectly for this. Let us know what you've been using, though...... if it's something more weather resistant that could be a very good thing.

[DClark]

YES!, it DOES work & we have been doing that mod to GSs over @ www.thegsresources.com for years! PLEASE don't coment negatively about something you have NEVER tried! It WORKS!!! PM me if you want the P/N for the relay. Ray.

Not being negative, just giving what I think is a better/different route. Also, forgot to add that I have dynacoils and a iridium spark plugs (which require less voltage for sparking).
My cold weather starting is better and I have started and ridden the big kat in temps in the teens.
Before anyone reaches for a cc and a place to buy them, let me add that the coils are limited by the voltage they recieve from the ignition module and I didn't notice any difference in how the bike ran. I even kept the plugs in stock gap. Right now, I have them gapped just slightly larger than stock.

[mak68]

Well, I had to postpone the coil relay mod, as the starter relay/solenoid crapped out on me on Saturday. Replaced it with this and she's back in action:



Anyway, I'll get back on track with the coil relay mod tomorrow night and see what happens.

Cheers

[DClark]

Anyway, I'll get back on track with the coil relay mod tomorrow night and see what happens.

Cheers

Whip out a meter and measure the voltage going to the coils before and after the relay install, if you can.

[mak68]

Whip out a meter and measure the voltage going to the coils before and after the relay install, if you can.

Sure thing.
First, my camera really sucks, but here goes.

So here's the voltage to coils before:





So I gathered what I was going to need:



Assembled:



Disconnected ground at battery.
Started install. The zip ties are only a temp solution. I have a pigtail block on order at work:



Hooked up the ground and power. The black wire on the left, and the orange wire with the in-line fuse. I used a 10 amp fuse as that's what the main fuse is too, and hooked into the power side of my brand new starter relay:




I threaded the 2 reds and 1 yellow along the harness.
At this point, instead of splicing directly into the kill switch wire, I simply pulled one of the stock orange wires at the coil (both orange wires that go to the coils are on the kill switch circuit anyways) and connected it to my yellow wire (power to automotive relay). The stock orange wire on the other coil I simply disconnected and capped with electric tape.
The red wires were connected to the coils, at the terminals where the orange wires were. One red for each coil.




and:


Reconnected ground at battery.

So after all is said and done, I did another voltage test on the coils, like DClark asked, and this was the result:



I took her out, and I'd swear she idles a tad smoother. Starting was almost instant too.

[GSXFJim]

I bet if you check all of your harness connections and the Off/Run switch you will find where the break down in voltage is.. Fix that and you wont need the relay.