Topic: CB750 kill switch wiring.

[MCRider]

OK I admit electrical is not my strong suit. I'm trying to wire in a "deadman's switch". A lanyard pulls a plug and kills the engine in the event of a get off.

The instructions say if you have a kill switch already (I do), then find the wire at a junction point, pull it apart and insert the leads from the DM switch. Easy peasy.

Well my manual says the kill switch (read ignition switch) has a B(lack) wire on one pole and a BW(black white) on ta other. In the Hlite shell, I trace the bundle from the right side switch. No B or BW wires. If I break the one B wire I do find, and interject the switch, I blow fuses. The only BW wire is plugged into other BW wires.

Any help is appreciated. I know its not that hard and I just have a mental block.

Is there a guide which identifies what color wire does what? I know B is power and G is ground. I think BW is power to the coils?

[70CB750]

Why don't you track the BW wire from coils, that's where it goes from the kill switch?

[madmtnmotors]

I know B is power and G is ground. I think BW is power to the coils?

Correct. The kill switch is normally closed (NC) and completes the switched hot circuit (B) to the coils (B/W).

[edwardmorris]

K2 wiring diagram for ref

[MCRider]

Why don't you track the BW wire from coils, that's where it goes from the kill switch?

My bike's strapped to the trailer and the trailer is in the shop. Not much room to move around, take the tank off, etc. I'm pretty sure this can be done in the headlight shell. Maybe not?

[MCRider]

Trying not to be too impish, but I need more handholding than that.

I understand better now, thanks 70CB. But not any closer to getting the switch wired in. Where is the B/BW connection? Is it not in the shell?

[MCRider]

Thanks EM, I do have that diagram and found the Ignition Switch (Kill switch) picture. But it does'nt give me where do I make the splice. OR maybe it does and I'm just not catching on.

[70CB750]

No, it is in the Kill Switch.

Kill Switch gets key switched power in (Black Wire) and BW wire goes from KS to coils.

I would not mess with the right hand control, much easier to splice between KS and coils.

[MCRider]

No, it is in the Kill Switch.

Kill Switch gets key switched power in (Black Wire) and BW wire goes from KS to coils.

I would not mess with the right hand control, much easier to splice between KS and coils.

Ahhhh! Now the fog lifts. Sounds like the tank must come off?

[70CB750]

Well it depends, I usually run wires inside handlebars and I would have to have really big reason to pull it out

On the other hand, power to coils is basically in the open, you could insert a wire jumper - without cutting the harness - between coils and harness and use this jumper to connect your dead man switch.

[MCRider]

Looking at the diagram, the BW wire is only used for power to the coils. It makes an appearance in the headlight shell. There is a mail/female connector. Could I not unplug that, insert the DM switch leads, and accomplish my goal?

[70CB750]

That would work 

But I am curious how will you use this switch?  Tied to your hand?   

Looking at the diagram, the BW wire is only used for power to the coils. It makes an appearance in the headlight shell. There is a mail/female connector. Could I not unplug that, insert the DM switch leads, and accomplish my goal?

[MCRider]

That would work 

But I am curious how will you use this switch?  Tied to your hand?   

Looking at the diagram, the BW wire is only used for power to the coils. It makes an appearance in the headlight shell. There is a mail/female connector. Could I not unplug that, insert the DM switch leads, and accomplish my goal?

YEs it is brand name kit, approved by various sanctions. The switch is a clamp on the bars with a socket in it. Plug the socket plug, about the size of a land line phone wall plug, into the socket on the clamp. It has mild resistance, so it will stay put.  A fixed length lanyard is affixed to one's wrist. Should the errant get off occur, the plug is pulled out and the engine dies.

The East Coast Timing Assoc requires it and we hope to go there this spring. Lucas Oil Drags doesn't require it for our class, but the next class up does, so what the heck.

[70CB750]

Gotit.

And here I thought you want to it for your commute, hmmm 

[MCRider]

Could I offer an option: splice your new DM in lieu of the right hand control, thereby leaving the stock wiring unmolested. Yes, you can use the connection in the headlight, but easier to find the pigtail connection from the RH control, eliminate it, and plug the DM in its place. Make sense? Unless there are other functions in use from the RH control, this is the easiest and most reliable method.

I see what you're saying, but I don't want to disable anything in this process. Its still a street bike after all.    

If I've got this right, all I'm going to have to do is unplug the BW wire at its juncture in the Hlite, crimp a mail and female end onto the switch leads, and plug them into the BW wire. So no molestation. OCICBW

[MCRider]

Well, if you run the DM than you either supersede the KILL or you run in series to it. So that is a logic gate to think through.

I don't know, I'll let you know. 

[Mantree]

Why not just snip the hot wire just before  the coil and install it there easy to get at

Sent from my ME302KL using Tapatalk

[70CB750]

^^^ that was my very first idea.

[MCRider]

Indulge my ignorance. Is there a common hot wire for both coils. Or if you snip one, won't the other still fire?

[Patrick]

Hook it to the wire that feeds the kill switch, not the coils. That's the black one into the switch, isn't it?

[MCRider]

Hook it to the wire that feeds the kill switch, not the coils. That's the black one into the switch, isn't it?

That's my approach. I think its the BW.

[oldhatt45]

MCRider,

The Black/White wire from the existing Off-Run-Off (Kill) switch is what you want to interrupt.
WHen I put in my Hondaman Relay Mods, this is one of the mods I did to put in the Off-Run-Off relay.
If you look at the diagram I've attached, look at the Off-RUn-Off relay.  You don't need any of the relay wires, you just need to look at the Black/White wire from the existing Kill (Off-RUn-Off) switch to the coils.

I hope this helps sort it out.  If not, just ask.

Charlie

[MCRider]

MCRider,

The Black/White wire from the existing Off-Run-Off (Kill) switch is what you want to interrupt.
WHen I put in my Hondaman Relay Mods, this is one of the mods I did to put in the Off-Run-Off relay.
If you look at the diagram I've attached, look at the Off-RUn-Off relay.  You don't need any of the relay wires, you just need to look at the Black/White wire from the existing Kill (Off-RUn-Off) switch to the coils.

I hope this helps sort it out.  If not, just ask.

Charlie

Thanks Charlie: That puts a cap on it. Will do next time I'm in shop. I, too, have the Hondaman HLight relays. I felt pretty proud having wired it correctly, but his instruction and jumpers left little to not understand.
Ron

[oldhatt45]

Ron,

You're Welcome.  I know that electrical schematics can be difficult to understand for some.
Glad the diagram I attached helped out. 

Charlie
PS:  I also have a diagram more specific to the K1-K4 models if you want or need it. 

[Phoenix]

Charlie
Could you please post the schematic for the k1-4.  The one you posted is great.
Thanks,
Ed

[oldhatt45]

Phoenix,


Here is the schematic for the K1-K4.
You're Welcome. 

Charlie

[Mantree]

Indulge my ignorance. Is there a common hot wire for both coils. Or if you snip one, won't the other still fire?

The coils are both fed by one wire that splits off to both coils

Sent from my ME302KL using Tapatalk

[edwardmorris]

This is why you need a DMS on a track bike

https://www.facebook.com/1392364424364539/videos/1670130959921216/

[Airborne 82nd]

Phoenix,


Here is the schematic for the K1-K4.
You're Welcome. 

Charlie

Wouldn't happen to have a drawing like that for a 750K8 to post?

[oldhatt45]

Airborne,

I just looked at the K8 wiring diagram and it looks like very little changed
According to this schematic http://manuals.sohc4.net/cb750k/technical_reference/WD750K8.jpg
The wire colors for  what you need to tap into look to be the same as the K6 diagram I originally posted further up in this thread.

If you're going to do the relay mods, you should probably pop the headlight and look inside the shell and verify wire colors. 
The 2 headlight relays, the Off-Run-Off relay, the Start button relay, and the horn relay all will go in there. 
The only relay that goes somewhere else is the ignition Switch relay which goes under the left side cover near the rest of the electrical stuff.

Hope this helps.

Charlie
PS:  If you need to talk this over, pm me and we can arrange that.

[MCRider]

This is why you need a DMS on a track bike

https://www.facebook.com/1392364424364539/videos/1670130959921216/

WOW! I'm surprised they don't require it. Those bikes run alcohol I think.

[MCRider]

MCRider,

The Black/White wire from the existing Off-Run-Off (Kill) switch is what you want to interrupt.
WHen I put in my Hondaman Relay Mods, this is one of the mods I did to put in the Off-Run-Off relay.
If you look at the diagram I've attached, look at the Off-RUn-Off relay.  You don't need any of the relay wires, you just need to look at the Black/White wire from the existing Kill (Off-RUn-Off) switch to the coils.

I hope this helps sort it out.  If not, just ask.

Charlie

Perfect. The BW wire in the shell has a male/female connector. I just pulled that apart, plugged in the deadman switch, after crimping on a male and female, and was in business. I knew it was simple, I was just stuck in my head. Thanks Charlie.
Ron

[oldhatt45]

Ron,

Glad you got "unstuck". 
Not like I've ever had that happen to me!   Hahahaha
And even better you got it done and it works the way it's supposed to!!!!!!
It truly does take a village.     

Charlie