Topic: Motogadget mUnit - CB750 Chopper wiring

[jphoto003]

Hey all, I have a 73 CB750 chop and I think I am almost done drawing up the wiring diagram with the motogadget mUnit for before getting busy. I have a santee box for it with a spring loaded key switch, I have a few question and was wondering if anybody on here can shed some light.

First question; What size fuse do you guys run for those with the mUnit?

Second question; What goes on the left terminal on the key ignition switch? Do I move the mUnit lock (out) to that position?

The way it is wired right now, the wire on the left terminal goes up to the headlight bucket and splits into the red wires on the speedo and tach. I've seen people wire their speedo and tach wires in the aux in of the mUnit.

Let me know what you guys think! Thanks, -J

[jphoto003]

Hey @calj737 I don't have a start button on my handlebar, I have a spring loaded turn key switch meaning I start the bike like a car by turning the key in all the way. Let me know if you know what I mean by that.

And we are on the same page on the AUX part, just got my IGN system wired and also the gauge lights and running light will be on there as well.


Also forgot that I had a red wire running from selanoid to the start out. I added it on the diagram (red/green outline). Thats why I had the start in wired on the key switch(previous diagram). I just dont have an idea how the turn key switch works, my problem figuring out right now is how to activate the selanoid/starter when the key is turned in all the way for starting the bike. Is it the orange wire that goes to start in?


updated diagram below. Moved the bottom of key switch red wire to the battery (+) and the black wire from reg/rec to the 'LOCK'

[jphoto003]

@calj737 Thanks for helping sort through this! A lot of good points on that last reply. And to start you're right about the orange, I don't know what part it actually plays. I got it from how my bike is wired originally when I got it. Looking at other diagrams online, I felt like it didn't need to be part of the wiring. I will check out the key switch and take some pics.

And with the left side of the munit only looking for GROUND, does that mean one pole of the key switch will have to connect to ground? I'm starting to think maybe the orange goes to start but yeah I just got more confused haha.

hmm...


Maybe seeing how my bike is wired without the mUnit will make more sense to kind of see where I got some of the wiring.

[jphoto003]

@calj737 could it be possible that it is getting grounded through being mounted on the electrical box or the chasis?

Im at the airport now and wont be back to my bike til wednesday, on the meantime I'm still online looking at other peoples wiring diagram and came across this one. It looks to me that I am running the same key ignition switch. And it looks like the middle terminal on the key switch is labeled 'str' im assuming the start impulse?

[DaveBarbier]

On my 550 I'm using a 15amp fuse for the m-Unit. But I have my reg/rec wired directly to the battery (not tied in to the m-Unit power source like you) and that has a 30amp fuse.

[scottly]

Let me know what you guys think! Thanks, -J

Why are you using an expensive, complicated M-unit on a simple chopper wiring system??

[jphoto003]

@calj737 yeah, I think I'm gonna start diving in the wiring when I get back just to get an idea on whats what. Thinking about unhooking the orange on the key switch, and see if the starter is activeted when turn the key in to start. We'll see. Thanks again will check back in when I get back home

@scottly because why not? Haha I didnt get the munit brand new and i have a few tricked out ideas on lightings i think the m unit will help out. Im not feeling the birds nest in the headlight bucket.

[jphoto003]

Took your advice on this one @calj737 and I took the key switch and used a multimeter to see the flow of electricity on the key switch.

As suspected, the orange wire that is connected to the solenoid is the start impulse wire. Took a video below of me going through the key ign switch. Also have an updated diagram, keeping in mind what @davebarbier said about his fuse set up.

Let me know if you guys think this latest diagram makes sense. Also do I just leave the accessories pole open without any connection?

Thanks so much, you guys are a big help!

The birds nest inside the box (Theres also a nest in the headlight bucket)

[jphoto003]

@calj737 so just to get it clear this time around, I have to bypass the m unit start if I wanna use the key switch to start the bike. And the only way I'll be able to use the m unit start is if I use a separate momentary push button to activate my starter?

noted on the cheap connectors!

[jphoto003]

Finished wiring and fired up on first pass.

Here's the video of me starting the bike. https://www.instagram.com/p/BEAeHXLCHK9


below are two versions of using the motogadget m-unit for your cb750. Thanks a lot for the help @calj737


This wiring diagram is what worked for me, by keeping the turn key switch. By passing the start function of the mUnit. Another version of the diagram under this one which is set up to use a push start button which uses the mUnit start function. Hope this helps in the future!






This version is for using a push button.