Topic: m.Unit Wiring Diagram

[Ellz10]

Anyone have an m.Unit Wiring Diagram for my bike? It's a 1977 Honda CB750 K.

[calj737]

There isn’t a specific diagram for a bike. The wiring is based upon your accessories, gauges, indicators, switch gear etc.

List your gauges, what indicators you have, brake light, left and right controls. I’m sure I have something close in my library.

[Ellz10]

There isn’t a specific diagram for a bike. The wiring is based upon your accessories, gauges, indicators, switch gear etc.

List your gauges, what indicators you have, brake light, left and right controls. I’m sure I have something close in my library.

Lithium ion rec/reg, bates style LED taillight, m.blaze disc turn signals (L&R), motogadget m.lock, motogadget m.stop, 12-volt horn, mo.switch 3 button switches (L&R), 6.5" LED Projector headlight, Daytona Velona speedometer, Daytona velona Tachometer. think that's about it.

[CB750R]

did you see this post?

http://forums.sohc4.net/index.php/topic,190806.0.html

[Ellz10]

did you see this post?

http://forums.sohc4.net/index.php/topic,190806.0.html

I saw that but I don't have the m.Button or an key ignition switch, nor do I have rear turn signals. I also am using points, not an electronic ignition

I'm also curious as to what I need to buy to make my front brake blend with this m.Unit system - My front brake combo is the Brembo 19RCS Corsa Corta. How do I go about tying that into the electrics?

[CB750R]

Buy the brembo brake light switch and wire it in as shown, that’s a good start, the rest your going to have to do your homework, odd wanting to fully rebuild a wiring system and retain points. You’re going to have to find out if that’s possible.

[Ellz10]

Buy the brembo brake light switch and wire it in as shown, that’s a good start, the rest your going to have to do your homework, odd wanting to fully rebuild a wiring system and retain points. You’re going to have to find out if that’s possible.

It's not one bit odd and I already know it's possible. Why waste money on electronic when I can have the reliability and longevity, not to mention save money, with points. I've also got Mark's transistorized ignition to wire in.

[Ellz10]

I'll just take the diagram from that Rhona guys post and delete all the stuff on it that I don't have nor need (i.e the m.Button, rear turn signals, ect) and I'll see how that goes. Thought I'd get a bit more help from people in this section of the forum lol - I guess trying to learn has become more difficult.

I admit I'm not very adept in the electrical aspect of anything really, which is why I'm here asking for help from the fellas that are skilled and knowledgeable and have done these things.

[calj737]

In order to wire up an mUnit with all the electronic gadgets you’ve bought, you need some fundamental skills in electrical. A diagram has some info associated with it, but the underlying comprehension of what does what is essential. Have you bitten off more than you can chew? Is there someone nearby you who can provide skilled assistance?

[CB750R]

Sorry man, I didn’t see the point of going to a new wiring harness and control unit without modernizing your ignition, I see you have modernized it to some degree.  Have you at modernized your reg/rectifier? From the little I know of the M-units they like a specific range of voltage, it would suck to fry one due to the old regulators.

I’ve installed a couple brembo RCS M/C-s  on other more modern bikes, the brake switch is pretty basic so when you ask questions of that level I kinda assumed that was the level of technical electrical knowledge. Unless you happen to find someone with the exact same list of modifications you have, the best your going to get is someone else’s wiring diagram, unless someone is willing to make one for you.

[calj737]

Have you at modernized your reg/rectifier? From the little I know of the M-units they like a specific range of voltage, it would suck to fry one due to the old regulators.

You are mistaken, the mUnit does not have a condition dependent upon the Reg/Rec. It’s looking for 12v plain and simple. A lithium battery does however have a preference for modern charging components as they have very different charging curves than lead acid batteries.

[CB750R]

You are mistaken, the mUnit does not have a condition dependent upon the Reg/Rec. It’s looking for 12v plain and simple. A lithium battery does however have a preference for modern charging components as they have very different charging curves than lead acid batteries.

Ok good to know, I must’ve taken that lithium info out of context.

[Ellz10]

Any particular way I should set my tray up that would be more beneficial/easier, before I drill the holes and weld the bolts?

This is what I came up with. I obviously don't have the mo.stop in there, but it's tiny enough not to make a difference in space.

[calj737]

Provide as much airflow around the Reg/Rec as possible. Perhaps even make some drilled holes below it with a 1/8” drill to create a “screen” for more air. The small amount of moisture that might infiltrate the tray should not be a problem with the air flow to dry it out.

[Ellz10]

Provide as much airflow around the Reg/Rec as possible. Perhaps even make some drilled holes below it with a 1/8” drill to create a “screen” for more air.

That's a good idea, I'll do that tonight, thank you!

[Ellz10]

So I went ahead and borrowed Revival Cycles diagram (credit to them) because it's quite close to what I have going.

Obviously I edited it to suit my bike.

You can see I left the "Key Switch" emblem on there with its accompanying red and brown wires. I, however, am going keyless, with the m.Lock which has red, brown, and black.

Perhaps a dumb question (or rather common sense), but are the red and brown wires from the m.Lock going to where the red and brown wires would go with the "Key Switch"? And then the black wire on the m.Lock gets grounded?

[calj737]

From recall, Red is power, Brown to mUnit LOCk, Black to ground.

[Ellz10]

From recall, Red is power, Brown to mUnit LOCk, Black to ground.

That's what I figured, thank you.

Next question - I'm testing out the m.unit to make sure it operates and functions correctly and for some reason AUX 2 light goes on and stays on. I've tried troubleshooting and there's no mention of it. Any ideas?

[calj737]

It’s merely indicating that power is available on that port as an output source.

[Ellz10]

It’s merely indicating that power is available on that port as an output source.

So the AUX 2 light will always be lit up when the m.Unit is in operation because there's available power at that port?

The video I watched showed the gentleman doing the same process, setup and all, and his AUX 2 wasn't lit up, that's why I thought to ask.

[calj737]

It may be in the software setup that either you or he doesn’t have AUX2 similarly.

[Ellz10]

It may be in the software setup that either you or he doesn’t have AUX2 similarly.

Oh I didn't think about that. I'll be sure to update to the newest software once I get it synced to Bluetooth.

Next question - in the wiring diagram their starter solenoid shows the 2 main wires going to battery and starter - then 4 individual wires going to START, BAT, REG/REC, and GROUND.

My starter solenoid only has 2 wires, instead of 4. Obviously my green/red goes to START, but where does my red/yellow go to, to BAT or GROUND?

[Ellz10]

Semi-unrelated question for you Cal - if I get my electrics tray powdercoated, will the powdercoat interfere with the grounding of the m.unit on the tray or no?

[RAFster122s]

If you are powder coating a tray or part that bolt's to another part, bare metal contact is needed between the bolt on part and the frame...if that isn't achieved then you need to sand or scrape it it bare metal to make contact with the object you are screwing into and battery or frame ground. Battery and frame ground points have to be at the same level or problems can develop.

Case in point, if the headlight bucket ground isn't maintained then the bike often will use the steering neck bearings as an electrical path which can lead to scorch marks spots on the bearings.

[Ellz10]

If you are powder coating a tray or part that bolt's to another part, bare metal contact is needed between the bolt on part and the frame...if that isn't achieved then you need to sand or scrape it it bare metal to make contact with the object you are screwing into and battery or frame ground. Battery and frame ground points have to be at the same level or problems can develop.

Case in point, if the headlight bucket ground isn't maintained then the bike often will use the steering neck bearings as an electrical path which can lead to scorch marks spots on the bearings.

Okay so when I weld the threaded part of 2 bolts to my electrics tray and tape off the threads so they don't get powdercoated I should be fine, because both sides are getting clamped down with a bolt screwing into the frame?

Forgive my quick awful drawing.