Coil relay mod

[Narcoleptic_Snowman]

Do it! Do it now! I went down to autozone and grabbed some random oem relay and followed the instructions on a thread I found around here. I then attempted to start my bike and... wow. Holy crap it was easy to start... now, my bike still idles like garbage due to (what I hope) the carbs being out of synch, but does idle much easier. It doesn't seem like it's trying to die. I just wanted to say thanks to whoever came up with this, and to tell everyone else that hasn't done it, to do it.

 

[80GS750]

i may run to autozone and pick the stuff up for this tomorrow...

i need to do this, enough reading about it

 

[Steve]

When you go to Auto Zone, this is what you are looking for. Scroll down in the link, find the two Pilot accessory relays, PL-RY1 and PL-RY2. The PL-RY2 is similar to the Bosch-type relays that many of us are using, and numbers its terminals the same as all the documentation available on this board. The PL-RY1 might also be used, but you will have to experiment with the terminals. The PL-RY2 is usually found along with the driving and fob lights.

.

 

[PAULYBOY]

Snowman, it really is amazing, isn't it? Wait til you get yer other issue straightened out. Yer gonna love it. Hope you got a strong grip, cuz the bikes gonna rip yer shoulders out.

 

[80GS750]

well im going right now to buy a relay and fuse holder....

we'll see how well it works... ill report back soon

 

[80GS750]

well guys i joined the club!!!

it was really easy, i took about 30 minutes and took my time, soldered all the connections and made it really durable.. should last forever now!

heres a pic of my completed work.

 

[cyberdork]

What's this about? Possible on a 700?

 

[hvfracingwilly]

I completed the relay mod today also, it really is worth ever dime you spend on it. Bike started better and idled better also. Amazing what 5 bucks and 30 minutes can do for these bikes!

 

[doctorgonzo]

What's this about? Possible on a 700?

Search for it, there are tutorials on it on the boards. It involves running a fused hot wire direct from the battery to the coils thus bypassing your old wiring harness, kill switch etc... I went from having 9 volts at the coil to having 11.5. This means stronger spark from the plug.

 

[Macmatic]

Any common reasons this doesn't work? I've tried two relays and triple checked the wiring but I'm getting a spark that if anything is worse than the stock setup.

Wiring I have:
30 - 12+ via fused lead from battery
85 - ground to R/R, ignitor mount bracket which is grounded directly battery -.
86 - O/W wire from one of the coils.
87 & 87a (Both of these are cold when ignition is off, 12+ when relay clicks on with ign) Wired one coil + terminal to each.
Coil NEG terminals connected to existing ignitor grounds.

I also took a different coil that tests good arcross the low voltage and high voltage sides and wire 12v+ directly to the + terminal and connected a wire to the - terminal. I tapped the battery - terminal with that but the best spark I got was at the battery terminal... with the coils wired in I at least get a feeble spark at the plugs but with this unmounted coil I got nothing, does it need to be mounted as well as have the signal ground?

Thanks,
/\/\ac

 

[salty_monk]

I think you need to be careful when using 87A... On some relays it's a normally open switch on some (which seem much more common these days) it's a normally closed switch.

It sounds like yours is working the right way though.

Other than that, no ideas...

What voltage are you now getting at the coils with the kill switch turned on? What guage wire are you using? Is it old wire that could have overheated in the past?

Dan

 

[cyberdork]

Wayyyy above my head, sucks too because my bike is a PITA to start.

 

[Macmatic]

Hey Cyberdork, don't give up! This is really pretty simple to do and I'm the only one I've read about with a problem. From what I've seen on other bikes this should be one of the first mods anyone does. I'm a believer, I just haven't found the true path (to ground) yet.

Salty,

I'm getting 11.7v at the relay and using 12ga for the 12+ and 14ga for everything else. The wire came from a Bobcat main harness I replaced a year or two ago and is in great shape. The Bobcat was only a couple of months old and had an engine fire, the sections I saved were far away from heat and undamaged....but full of really nice wire!

Man, this bites. I'm trying to solve other issues and I thought I might as well go ahead and do the coil mod to help with the dead cylinder but now this seems to be a step back! I'm going to hook it up the factory way again tomorrow and check the spark again. Doesn't make sense that this could be worse!

My factory wiring is pretty good though, no brittle insulation and even the bullet connectors don't really have corrosion. The only corrosion I've ever seen was in the HT leads. I was getting around 11v at the coils before the mod.

thanks!
/\/\ac

 

[almarconi]

87 & 87a (Both of these are cold when ignition is off, 12+ when relay clicks on with ign) Wired one coil + terminal to each.
Coil NEG terminals connected to existing ignitor grounds.

I would route the the power to + terminals of the coils from 87. This may be causing your problem. On the bosch relay 87 is NO and 87a is NC. NO will close when the relay is activated, and NC will open. You'll want to connect the coils to NO. Hope this makes sense.

 

[Narcoleptic_Snowman]

The relay I picked up had the 87a. I originally tried to hook one coil up to 87 and one to 87a. The 87a didn't seem to make any connection at all, as the two cylinders the coil was hooked up to weren't firing. I then connected both of them to 87. I just used a butt connector, stuffed the two o/w wires into one end, and a little chunk of red in the other end. Seemed to work well.

 

[cyberdork]

Alright did some more research and finally understand it, just needed a better diagram. Only bad thing is I'm going to Aruba for a week so I'll probally forget about it lol. As soon as I get back I'm getting the bike inspected and on the road, so I don't know if I should risk doing this before inspection or not.

 

[Macmatic]

I just bought and tried a 4 terminal relay, same results. I didn't think the relay was the problem since 87 & 87a both had no voltage until the relay was energized and 12v+ as soon as I switched to RUN.

I asked this over in tech info but never got a reply: It isn't going to hurt the coils to hook the positive directly to the battery positive and make momentary contact between the neg and battery negative, right? I tried that with a '95 Kat coil the other day and didn't get anything although it seems like it should be a good coil. I don't see how this could fry a coil unless 1/2 second or so is too long, I never grounded it for longer than that.

Does the coil need to be grounded to the frame via the mounts to work?? I had this coil free of the bike and only connected to the wiring +/-.

This SHOULD have given me a nice fat spark I think. For comparison and to make sure I wasn't seeing it as worse than it really is I just pulled the plug from my line trimmer and checked that spark. It looked WAY better, nice and blue and fat where the bike spark is blueish, thin and hard to see. Maybe I should rig up a couple of Stihl coils!

Maybe its time to spring for a set of Dyna coils? I've been meaning to do that for a couple of years but she always ran so sweet I never got around to it.

I have another set of GS750ES coils and at least one set each of '82 GS650 and GS550 Kat coils to dig up and try first....won't be ordering new coils for at least a paycheck anyway.

Thanks for the input,
/\/\ac

 

[doctorgonzo]

If these are original stock coils, the wire or the cap could be the source of the weak spark instead of the coil. Just a thought.

 

[Macmatic]

Breakthrough

Breakthrough

So now that I discovered this I remember reading it in manual but until now I never picked up on this and no one in either thread had asked an important question.

I only had one plug per coil grounded, grounding the second plug made a major improvement in the spark It still isn't the fattest spark I've seen but it looks acceptable and many times better than the weak sauce it was before.

Tomorrow I'll try starting and running again... I hope the coil mod makes a difference, I had pretty good voltage with the stock wiring. I think I only gained about .3v but thats for another thread.

Thanks for the help everyone!
-/\/\ac

 

[horror1972]

Coil relay mod

It isn't that hard, a relay:

85 is ground and 86 is any positive power.
this 2 terminals are the coil of the relay, or the electronic switch.
you can feed 86 from about 9 to 14 volts.
30 is the input, and 87 the output, so it doesn't matter what's on the 30 terminal, the only thing it does is connect 30 and 87 when the coil is activated; 78a works the opposite; when the coil isn't activated,it's connected with 30, and when the power is on 86, it disconnects.

so what you do with this mod is using the o/w wire from the killswitch to switch the coil (86) and get a fresh battery power from the 30 terminal at 87.
unless you have bad wiring or a bad killswitch, it doesn't make any difference.

hope this make sence.