Topic: What is an m unit?

[eldar]

Been a long time since my 78 750 was fired up, as it needs a rebuild. What is this m unit thing, and what does it do? What are the pro/cons?

[calj737]

It’s a modern power relay that allows you to fully centralize the distribution of the power to the functions of your bike. If you are not fully re-wiring your bike then don’t use one as the existing wiring needs significant modification. But if you are “customizing” your bike, using non-stock components, and want a cleaner, more simplified installation, then you might consider it.

There are a few “extra” functions available with the different models over stock behavior: self-canceling indicators, variable brake light options (flash x3 then solid, flash persistently, etc) optional running light power levels, Bluetooth connectivity for keyless start, GPS integration for speed, etc. Are these “necessary”? Nope. So many people desire these features? Yep.

Downsides: you really need to re-wire your bike for best results. They run about $300. You can run much smaller wiring in your looms, so if you are connecting to existing components, there’s that mismatch.

Up to you-

[eldar]

Hmm, well I'll probably have to do some wiring work, but I'll probably forgo something like that for now.

[Ellz10]

It’s a modern power relay that allows you to fully centralize the distribution of the power to the functions of your bike. If you are not fully re-wiring your bike then don’t use one as the existing wiring needs significant modification. But if you are “customizing” your bike, using non-stock components, and want a cleaner, more simplified installation, then you might consider it.

There are a few “extra” functions available with the different models over stock behavior: self-canceling indicators, variable brake light options (flash x3 then solid, flash persistently, etc) optional running light power levels, Bluetooth connectivity for keyless start, GPS integration for speed, etc. Are these “necessary”? Nope. So many people desire these features? Yep.

Downsides: you really need to re-wire your bike for best results. They run about $300. You can run much smaller wiring in your looms, so if you are connecting to existing components, there’s that mismatch.

Up to you-

Cal, you put it so eloquently that I made my mind up to get one!

Hah! I actually came looking for this exact info. I realize that this unit would have so many benefits, and seeing as I'm rebuilding from the frame up, I could utilize this.

Is there another thread and/or post that goes into more vivid detail and instruction on the many variables of the M.Unit? I'll need much more info before I'm able to fully grasp the understanding and be able to actually do it.

[calj737]

Not really a single thread that encompasses all the features. There are newer units that do and don’t have Bluetooth so that alone effects “features”.

If you list your componetry, bike style, some sketches/pictures, it may help guide you in a direction. I have ample wiring diagrams for other bikes that adapting one for your specific needs is easy.

[Ellz10]

Not really a single thread that encompasses all the features. There are newer units that do and don’t have Bluetooth so that alone effects “features”.

If you list your componetry, bike style, some sketches/pictures, it may help guide you in a direction. I have ample wiring diagrams for other bikes that adapting one for your specific needs is easy.

Well I don't think I "need" the Bluetooth one, unless there are added benefits or features that could come in handy.

I suppose I'm curious as to how i would go about the wiring. I was going to buy a new wiring harness already (obviously mine is old and worn and some parts nonfunctional) so would I continue buying that but just taking some parts out as needed to suit to M.unit?

[calj737]

Nah, the stock harness would be a waste if you plan to use an mUnit.

Many folks who do opt for it are also doing so because they are using non-stock lighting, gauges, etc and want the ability to locate some items differently than stock.

Making the looms from the mUnit to the component and from the switch to the mUnit is super simple. Super simple.

See if you can answer these to help me understand your intent:
What gauge(s) are you planning on running? Stock? Aftermarket? Single multi-function gauge or dual gauges?
Indicator lights? Stock? Aftermarket? Location front and rear?
What switch gear do you plan to run on the handlebars? Stock? Non-stock, perhaps more modern donor from a later bike? Momentary switches (this is quite possible with non-stock, custom bikes)?
Where do you plan to locate the battery?
Stock Reg/Rec or aftermarket?

See, quite a few questions to answer then we can help you with the logistics.

[Ellz10]

Nah, the stock harness would be a waste if you plan to use an mUnit.

Many folks who do opt for it are also doing so because they are using non-stock lighting, gauges, etc and want the ability to locate some items differently than stock.

Making the looms from the mUnit to the component and from the switch to the mUnit is super simple. Super simple.

See if you can answer these to help me understand your intent:
What gauge(s) are you planning on running? Stock? Aftermarket? Single multi-function gauge or dual gauges?
Indicator lights? Stock? Aftermarket? Location front and rear?
What switch gear do you plan to run on the handlebars? Stock? Non-stock, perhaps more modern donor from a later bike? Momentary switches (this is quite possible with non-stock, custom bikes)?
Where do you plan to locate the battery?
Stock Reg/Rec or aftermarket?

See, quite a few questions to answer then we can help you with the logistics.

Okay perfect. Well first what do you mean by looms? The fabric that encompasses the wiring to keep it safe?

Second, I'm not sure which one I want yet, but I WILL be using an aftermarket single guage cluster (speedo/tach) with all bells and whistles. One like the Acewell 4553. Its a single multi-function. I'll attach a pic. I'm definitely open to suggestions if you know of one that is better!

As far as indicator lights, I'll be using a round hot-rod style tail light (2 1/4"), aftermarket. I'll attach a pic. Front turn signals will be the moto gadget bar end signals M-Blaze. Headlight and rear turn signals I'm not sure what they'll be yet, but obviously they'll be aftermarket LEDs akin to the indicators I've just listed.

Location of the taillight will be under the upkick of the hoop, wiring ran under the seat or perhaps thru the frame itself, haven't decided yet. Rear turn signals might be located right there with the taillight or next to the upper shock mounting, haven't decided on that yet either.

I was really digging the aftermarket momentary switches, 2 or 3-button switches on both sides or 2 on one side and 3 on the other, whatever is practical if possible? Or TWO 2-button switches right next to each other? As long as I have enough switches with buttons to utilize the functions I need, signals, hi/lo beam, horn, ect.

I'll be utilizing the anti-gravity battery, placing it flat on its side located in the electronics tray I've fabricated under where the seat will be. Not sure which size anti-gravity battery I'll need, I suppose it'll depend on what all I'm running, right?


One side note that I want to state is that I'm adamant about having just a single USB outlet mounted to the bike, I'll attach a pic.

Also, how would I go about buying all the necessary wiring for everything? Just buy the wiring separately or as a pack?

[calj737]

Unlike the stock harness, the easiest method for a custom wiring job is to orient wires from the R handlebar switch gear to the mUnit. That’s 1 loom. Then a separate look from mUnit to T side functions (lights, indicators, maybe gauge cluster). Ditto for L front side.

You can run a single wire to the TAIL for Brake and Light control. Then 2 wires for L/R indicators.

A 12amp/Hr battery is best with an appropriate Reg/Rec (lithium compatible).

Powering the USB will be done from AUX port on mUnit. Be careful about what you plug into it as it will draw a lot of juice from the stock charging system.

You can buy spools of wire in multiple colors and gauges from McMaster Carr quite easily. I use 22awg for switch to mUnit, and 18awg from mUnit to component. Battery to mUnit is use quality stranded 10awg. You can buy “Molex” connectors online to make connecting/disconnecting looms from components for service later.

[Ellz10]

Unlike the stock harness, the easiest method for a custom wiring job is to orient wires from the R handlebar switch gear to the mUnit. That’s 1 loom. Then a separate look from mUnit to T side functions (lights, indicators, maybe gauge cluster). Ditto for L front side.

You can run a single wire to the TAIL for Brake and Light control. Then 2 wires for L/R indicators.

A 12amp/Hr battery is best with an appropriate Reg/Rec (lithium compatible).

Powering the USB will be done from AUX port on mUnit. Be careful about what you plug into it as it will draw a lot of juice from the stock charging system.

You can buy spools of wire in multiple colors and gauges from McMaster Carr quite easily. I use 22awg for switch to mUnit, and 18awg from mUnit to component. Battery to mUnit is use quality stranded 10awg. You can buy “Molex” connectors online to make connecting/disconnecting looms from components for service later.

Okay. It sounds complicated but I am following you so far. Are there any aftermarket regulators and rectifiers that are actually worth getting? Any other aftermarket electronics that, in your opinion, are  better than OEM and worth it?

So 22awg for the wiring that will be going from the handlebar switches L and R, to the mUnit and 18awg wiring that will be going from the mUnit to everything else (headlight, guages, taillight, USB, ect)? And use a quality 10awg for battery to mUnit? Did I understand it correctly?

Also, I'm curious to know what all is no longer necessary by utilizing this mUnit device. For example, the fuse box conversion I had thought about getting at the very beginning thoughts of my build is no longer necessary, correct? What else is no longer needed.

When it comes to choosing a wire color, it would be prudent to pick the same color for each function as detailed/outlined in the manual, no? Or does it not matter at this point due to the customization of the entire thing?

[Ellz10]

So I checked into aftermarket reg/rec's and found this one. Plenty of good reviews, it's lithium battery compatible like you said, however my year isn't listed on their compatibility for the part. Is that because they're going based off of the stock motorcycle itself?

Would this actually work well for my purposes?

[calj737]

Okay. It sounds complicated but I am following you so far. Are there any aftermarket regulators and rectifiers that are actually worth getting? Any other aftermarket electronics that, in your opinion, are  better than OEM and worth it? No, outside the stock Stator, starter solenoid, there really aren’t “other components” that you won’t be replacing.

So 22awg for the wiring that will be going from the handlebar switches L and R, to the mUnit and 18awg wiring that will be going from the mUnit to everything else (headlight, guages, taillight, USB, ect)? And use a quality 10awg for battery to mUnit? Did I understand it correctly? Correct. For the USB connection to AUX, check the amp rating of that plug. You might need greater than 18awg.

Also, I'm curious to know what all is no longer necessary by utilizing this mUnit device. For example, the fuse box conversion I had thought about getting at the very beginning thoughts of my build is no longer necessary, correct? What else is no longer needed. You’re replacing the Reg/Rec components, replacing the fuse block, so just the starter solenoid.

When it comes to choosing a wire color, it would be prudent to pick the same color for each function as detailed/outlined in the manual, no? Or does it not matter at this point due to the customization of the entire thing?I think so. You can even locate striped wires if you are that intent on duplicating the colors.

Here’s how I run my wiring with momentary switches:

I run a solid GRN from the switch to the chassis. I then run a color consistent with the stock color from the switch to the mUnit input side (22awg for both of these legs). Then I use the same color (or striped version of it) from the output side of the mUnit to the component (R TURN for example). I group these in separate looms, one loom TO the the mUnit, one loom FROM the mUnit. That way, if I ever need to replace a component, alter the switch functions (maybe you had START on the R but now want it on the L for some reason) I don’t have to tear open a great deal of work to get to it.

I don’t run separate looms for each function, just each “category” of functions. All switch inputs are together, all TURN F are together, LIGHT/Gauge/Oil/NEU go together, etc. This allows me to run them as I need, strap them to the frame for a clean install, and know what section is doing what. It’s a custom bike, so put as much thought into the final outcome and serviceability as you can.

Yes, that Reg/Rec from Ricks is recommended. The “year” of your SOHC is mostly irrelevant as long as you are within the correct model. If in doubt, call Ricks to confirm.

[Ellz10]

Okay. It sounds complicated but I am following you so far. Are there any aftermarket regulators and rectifiers that are actually worth getting? Any other aftermarket electronics that, in your opinion, are  better than OEM and worth it? No, outside the stock Stator, starter solenoid, there really aren’t “other components” that you won’t be replacing.

So 22awg for the wiring that will be going from the handlebar switches L and R, to the mUnit and 18awg wiring that will be going from the mUnit to everything else (headlight, guages, taillight, USB, ect)? And use a quality 10awg for battery to mUnit? Did I understand it correctly? Correct. For the USB connection to AUX, check the amp rating of that plug. You might need greater than 18awg.

Also, I'm curious to know what all is no longer necessary by utilizing this mUnit device. For example, the fuse box conversion I had thought about getting at the very beginning thoughts of my build is no longer necessary, correct? What else is no longer needed. You’re replacing the Reg/Rec components, replacing the fuse block, so just the starter solenoid.

When it comes to choosing a wire color, it would be prudent to pick the same color for each function as detailed/outlined in the manual, no? Or does it not matter at this point due to the customization of the entire thing?I think so. You can even locate striped wires if you are that intent on duplicating the colors.

Here’s how I run my wiring with momentary switches:

I run a solid GRN from the switch to the chassis. I then run a color consistent with the stock color from the switch to the mUnit input side (22awg for both of these legs). Then I use the same color (or striped version of it) from the output side of the mUnit to the component (R TURN for example). I group these in separate looms, one loom TO the the mUnit, one loom FROM the mUnit. That way, if I ever need to replace a component, alter the switch functions (maybe you had START on the R but now want it on the L for some reason) I don’t have to tear open a great deal of work to get to it.

I don’t run separate looms for each function, just each “category” of functions. All switch inputs are together, all TURN F are together, LIGHT/Gauge/Oil/NEU go together, etc. This allows me to run them as I need, strap them to the frame for a clean install, and know what section is doing what. It’s a custom bike, so put as much thought into the final outcome and serviceability as you can.

Yes, that Reg/Rec from Ricks is recommended. The “year” of your SOHC is mostly irrelevant as long as you are within the correct model. If in doubt, call Ricks to confirm.

So the stator is obviously staying. But the starter solenoid too?

For some reason I thought the mUnit would replace the starter solenoid too. But the starter solenoid IS staying, right? Goes to show my lack of understanding. But I'm learning!

Cal, I'm very grateful for your input. I wouldn't be able to do this without it! Many thanks!

[calj737]

Yes, you need a solenoid for the starter. You can buy a modern replacement but it is still required. What is part of the mUnit is the starter safety unit.

[Ellz10]

Yes, you need a solenoid for the starter. You can buy a modern replacement but it is still required. What is part of the mUnit is the starter safety unit.

Okay that's what I'll do, because mine is old and has a small crack.

Does it still need to be placed in the rubber boot to prevent "shock"?

Is it okay to mount it at any angle in my electronics tray?

How would I go about getting a wiring diagram for the mUnit for my '77 K7; is there one available or am I going to have to just piece everything together by luck?

[calj737]

No rubber boot needed, that is mostly for insulation from electric shorting.

A specific diagram for your year isn’t required, but if you want to know the “stock” colors, then mostly any year 550 is close enough. I have a copy in color and multiple versions of mUnit installs with similar gear.

[Ellz10]

No rubber boot needed, that is mostly for insulation from electric shorting.

A specific diagram for your year isn’t required, but if you want to know the “stock” colors, then mostly any year 550 is close enough. I have a copy in color and multiple versions of mUnit installs with similar gear.

Okay perfect. The closer I get to installation, I'll give ya a shout for a look at some of those versions.

I'm curious about when it comes to the taillight. Is there a certain way to go about making it to where the taillight stays on, and flashes when the brake is applied. Or like you mentioned at the beginning of this thread (3x flash, then solid, ect). Does it depend on the taillight or the way its set up?

[calj737]

Configuring the behavior of the Brake light is done through the menus. If your TAIL and BRAKE light are single wire from mUnit to taillight, it’s super easy.

[Ellz10]

Configuring the behavior of the Brake light is done through the menus. If your TAIL and BRAKE light are single wire from mUnit to taillight, it’s super easy.

Assuming I have the mUnit Blue, correct?

Also, is the Mbutton worth getting? I've read VERY mixed reviews/opinions.

[calj737]

Blue or not, it’s the same for brake light options. Skip the mButton.

[Ellz10]

Blue or not, it’s the same for brake light options. Skip the mButton.

Okay awesome. Will skip the mButton.

Is this battery cable setup something I need? Or can I just go with a regular 10 or 8 awg cable?

[calj737]

That’s fine, but in the past all my mUnits came with a cable in the box. You do want an in-line fuse per the manual.

[Ellz10]

A 12amp/Hr battery is best with an appropriate Reg/Rec (lithium compatible).

Do they make a small lithium battery around 12 amp hours that's smaller than 2.75" wide?

Would I be able to get away with one of their 7 amp hours batteries? What would the downsides be?

[calj737]

A 7aH battery will provide you VERY LITTLE stored charge. So if you ride in and around town where limited RPMs and stop-go traffic occur, you’ll deplete the reserve charge since your bike needs to be above 2k RPM sustained to produce excess voltage.

Also, one good hit on the electric START will draw that sucker down pretty quick. If you have any problems cranking the bike, you’ll kill that battery.

[Ellz10]

A 7aH battery will provide you VERY LITTLE stored charge. So if you ride in and around town where limited RPMs and stop-go traffic occur, you’ll deplete the reserve charge since your bike needs to be above 2k RPM sustained to produce excess voltage.

Also, one good hit on the electric START will draw that sucker down pretty quick. If you have any problems cranking the bike, you’ll kill that battery.

Okay good to know. I'll just stick to the 12 and make it work in my tray.