Topic: M-unit wiring diagrams for SOHC/4 bikes

[theDQG]

I am working on a wiring diagram for my CB750 k4 featuring a M-unit blue, M-lock, etc.

I would like to invite everyone to post their M-unit wiring diagram(s) in this thread for purpose of sharing information or assistance.

I will share mine once it is done and reviewed for corrections.

Thank you in advance.

[calj737]

Go nuts

[theDQG]

I found this:

[Jnel]

This is mine.

Sent from my SM-N950U using Tapatalk

[roach374]

Go nuts

In your diagram, what do the circles with "M", and "G" in them represent? (Sorry if this is a dumb question).

[calj737]

Go nuts

In your diagram, what do the circles with "M", and "G" in them represent? (Sorry if this is a dumb question).

G is a reference to the Stator/alternator (oft referred to as “Generator”)
M is a reference to the Starter Motor (you know, the thing that makes the bike work under electric start)

Not dumb questions, just “new to electrics” questions 

[roach374]

Go nuts

In your diagram, what do the circles with "M", and "G" in them represent? (Sorry if this is a dumb question).

G is a reference to the Stator/alternator (oft referred to as “Generator”)
M is a reference to the Starter Motor (you know, the thing that makes the bike work under electric start)

Not dumb questions, just “new to electrics” questions 

Thanks!

One more question: In some wiring diagrams, I see the m-Unit's IGNITION output powering an ignition coil, and in others it's not. Which is "correct"? (Keeping in mind that my bike has TWO ignition coils, not one). Is this just to power the ignition coils, or does it replace the points for timing or something?

[calj737]

Depending upon which mUnit you have, you either use IGN or AUX to power the coils AND the electronic ignition (if that’s what you have). There is no power supply required for points and condensers.

[roach374]

Here's mine, but I'm still trying to figure out where the clutch / neutral switches should connect, in order to prevent the starter from starting (ie: only start when the clutch is engaged). I'm also not sure about the wiring to the ignition...

[calj737]

You can't really use the CLUTCH and NEU Safety switch in conjunction with the mButton.

With the mButton, a double tap of the START button (LH switch) will KILL the motor (if you didn't know).

[roach374]

You can't really use the CLUTCH and NEU Safety switch in conjunction with the mButton.

With the mButton, a double tap of the START button (LH switch) will KILL the motor (if you didn't know).

Right, but is there some analog / electrical way to wire the clutch switch (to the solenoid or something) to prevent the starter motor from firing? I like this as a safety feature (inability to start the bike when clutch is out).

EDIT: hmmm. Looking at the CB500 wiring diagram, it seems like the bike doesn't even have a clutch switch. Maybe the whole thing is academic.

[calj737]

You can wire it through the solenoid, but it won't interrupt the mUnit signal from START. With your diagram and using the mButton, the START switch is going to activate the IGN port no matter what you do with a CLUTCH or NEU switch. This is one reason why I never use an mButton.

True, the 500 never had a safety switch, but 550s did.

[roach374]

You can wire it through the solenoid, but it won't interrupt the mUnit signal from START. With your diagram and using the mButton, the START switch is going to activate the IGN port no matter what you do with a CLUTCH or NEU switch. This is one reason why I never use an mButton.

True, the 500 never had a safety switch, but 550s did.

Fair enough, but will it prevent the starter motor from turning?

Alternatively, I could wire the start button in series through the clutch switch, but that's a lot of wire and somewhat defeats the purpose of the mButton.

EDIT: That is, of course, if a clutch switch existed on the cb500, which it doesn't.

[calj737]

Ignoring the mButton, you can wire the clutch lever switch inline to the solenoid, using the clutch switch as the "ground" for the solenoid. Power to it comes from IGN or AUX, but in order to transfer that power to the starter motor, the clutch switch would have to be pulled in. This in effect behaves as a NEU switch too, though it is NOT the same thing as the motor would start while in gear, but you'd have the clutch pulled, so as soon as you let go of the clutch the bike would move (if not also in NEU).

You can easily look at some later year 550 diagrams to see how the CLUTCH switch was wired to adapt yours if you ditch the mButton.

[roach374]

the motor would start while in gear, but you'd have the clutch pulled, so as soon as you let go of the clutch the bike would move (if not also in NEU).

This is basically exactly what I'm looking for. Cheers!

[freshtoday]

I just bought a camera for my honda cb750K2 and it says to connect to the ignition switch.Mine is sealed and plugs into the wiring harness.I need to find a wire that only has current when the key is turned to the on position..(cant read a schematic) .Im looking for the camera to go on when ignition is on and off when bike is off..Thank you in advance......TONY

[calj737]

I just bought a camera for my honda cb750K2 and it says to connect to the ignition switch.Mine is sealed and plugs into the wiring harness.I need to find a wire that only has current when the key is turned to the on position..(cant read a schematic) .Im looking for the camera to go on when ignition is on and off when bike is off..Thank you in advance......TONY

You can locate the BLK/WHT wire for the coils below the tank. The power up with the RUN and KEY ON.

[scottly]

I just bought a camera for my honda cb750K2 and it says to connect to the ignition switch.Mine is sealed and plugs into the wiring harness.I need to find a wire that only has current when the key is turned to the on position..(cant read a schematic) .Im looking for the camera to go on when ignition is on and off when bike is off..Thank you in advance......TONY

On Hondas, the solid black wires are hot when the ignition switch is on; black wires with stripes are switched, like the black white wire from the kill switch Cal mentioned.
There are several different places to tap into the black wire, such as the front brake switch.