Topic: 3-position automotive ignition, help!

[scatman200]

I'm wiring in an automotive type ignition starter switch (instead of using the button).  I have tried just about every configuration possible, and I either get no result or keep blowing fuses.  I've been hooking up the two blacks wires (assuming these are the power in, and the power out), to the posts labeled "Battery" and the other to the post labeled "ignition", and I get the accessory lights on just fine, however I can't seem to figure out how to work the starter into this equation.  The third post is labeled "solenoid", however the yellow/red wires doesn't seem to work on that post,

When I touch the yellow/red wire to any ground, the starter fires, however I can't figure out how to get this switch to function with the yellow/red wire.

[phil71]

I am not crazy about using a relay to trip a relay, but it's your only move here.
There are reasons that motorcycles don't have the 'momentary' start position on keyswitches.. but, if this is what you're going to do, here's how to do it. You'll need a bosch or bosch style SPDT 12V relay (about $4 in an honest auto parts store, i'd visit a car stereo shop though, where they have them in piles).
Here's the way to do it:

[scatman200]

Thanks Phil!  The yellow wire on your diagram is the yellow/red wire on the bike I presume? 

[phil71]

yes, and if you zoom in, you'll see it's actually yel/red. Is there any way to talk you out of this? It's a bad idea on a few levels.

[scatman200]

Thanks phil!  I had one of the specified relays kicking around.  The circuit certainly works now.  Why do you oppose this set-up?

[phil71]

Without getting too into electrical theory, the two coils in this setup create the potential for an inductive loop which could hold the starter on. You'd need diodes in two places to be certain that doesn't happen.
The other thing is that the starter button is on hand controls so that in a stall, you can keep your focus on riding and still start the bike when in motion. In this setup, you have to release one side of the bars to restart 'mid-flight'...

[vames]

I agree with Phil for a few reasons:

1) There's no headlight  cutoff in a momentary key switch, which means that (unless you have a pre-74 bike and physically turn off the headlight every time before you start) you are putting undue strain on your battery by running headlight and starter at the same time.

2) Having the button on the same hand as the throttle means you can give it a little gas and push the starter at the same time. With a key switch, your starting is a two-handed ritual.

[TwoTired]

I don't think the relay you are using realizes the bike you are wiring it to, and neither do we.
On some bikes the Yellow/Red supplies power, and on other bikes the Yellow/Red supplies Gnd.

[phil71]

his was a (-) trip.. apparently he's already got it working.

[scatman200]

^Yep, already got it working.  Thanks for the input guys, you all make valid points. 


vames:  As far as the headlight goes, my CB has a separate on/off switch for the headlight on the right switch housing.

I'm going to take all of this into consideration, and worst case, I'll revert back to the OE start button.  Thanks again everyone!