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I need help!

Welding, rebuilding engines, powdercoating, all easy, but I am no Harry Potter when it comes to the dark art of wiring!!

My loom is a working original mess, since i stripped and got rid of all old parts of my bike im left with an exposed loom which I decided to leave just to finish the bike.

Now i have more time and the weather is shit ive decided to either:

  1. Extend the loom to hide everything under the tank, keeping the battery and fuses and flasher unit etc in the small battery box i made under my seat. (i have a tiny 4 cell Antigravity battery which is awesome) which i can easily do... probably
  2. buy the m-unit from motogadget to eliminate a lot of the earthing wires, flasher unit, 2 of the three fuses and a few other messy bits probably, just really slimming down the loom
I really want to use the m-unit but im scared off by the old diagram of the electrics i have, i don't know where to start!

Ive attached to old wiring diagram, the simple one that motogadget supply as a working plan if anyone would like to draw me one...

wiring-diagram-cb250n-cb400n-all-models-1-pdf-march-3-2012-11-24-pm-346k.jpg

fahrzeugschaltplan_en.jpg
 

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Installing an m-Unit on your bike is about as straight forward as an install it gets. Without getting into the nitty gritty here's some info to get you started.

It helps me to understand how the m-Unit integrates into the system by breaking the wiring up into 3 subsystems.


1. Charging - This incorporates the wiring from your magneto or stator, Reg/Rec and battery. This all ties into the m-Unit at the 12V+ connection on the lower right side of the unit.
2. Ignition - This is your Points, CDI, ECU which ever you have along with your coils, ETC. This will tie into the m-Unit in one place only and that is the AUX outlet on the m-Unit which provides power to this system.
3. Ancillary (m-Unit) - The m-Unit among it's other features acts as a brain that controls voltage for everything on your bike aside from the charging system. This group also includes all of your lighting and switches, essentially anything that has an assigned input or output on the m-Unit.

Print out several copies of your OEM diagram. Using markers, trace out on one page the entire charging system. On another Page trace out the entire ignition system. These will remain relatively un molested other than where they derive their 12V power from.

Toss out any part of the wiring harness that doesn't involve the charging or ignition systems. The wire is old and it was low quality to begin with. Good wire in the lengths you need is cheap and worth the investment.

Get rid of the OEM switches. They are one of the most common sources of electrical faults on these old Hondas and while they can be made to work with the m-Unit they will never work as they were intended. There are many options for momentary switches on the market now and some of them are very affordable.


You'll also want to have:

1 A good wire diagram for the factory connections (also take photos of connector backs for wire locations)
2 Crimp Terminals that match the pins for your connectors
3 Wire to replace and extend sections of the factory harness
4 Main fuse, Gauge Fuse,
5 Wire loom
6 Heat shrink
7 Solder and solder iron
8 Time
9 Patience
10 Focus

In my experience it isn't that difficult to get the wires to connect from the correct things and make the system work. The difficulty comes in making it all look perfect and simple, and having it all in vinyl wire loom. It’s much easier if you just wrap it all after the fact with electrical tape or split weave loom. The biggest tip I can give is to pick one thing at a time and work it out

Break it down into bite sized pieces. Start with just one part, the headlight circuit for example, and knock that little bit out before moving on to the next. Doing it this way makes it a lot easy to wrap your head around it and easier to retrace your steps should something need debugging.





 

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Still REALLY unclear on what the heck these MotoGadgets actually do, and why they are SO expensive.
Looks like little more then a junction box.
 

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Still REALLY unclear on what the heck these MotoGadgets actually do, and why they are SO expensive.
Looks like little more then a junction box.
It's a lot more than that. Actually a very clever little box of German engineering.
Don't let the fact the hipster crowd uses them in abundance cloud your judgement.

There are a good few videos online that explain them really well.

In short
All switch operate almost 0 volts
Solid stat electrics for the flashers (no flasher module to go wrong.
Built in protection and self diagnosis on on circuits in case of shorts
Built in alarm
Programmable lighting
Optional rfid (keyless ignition)
Works on 6-18v dc
And much more. Like I said very interesting bit of engineering.

Anyone with half a brain can wire a bike with one.
Even if they fuck it up the unit will kill the power instantly and tell them using an led what circuit they fucked up on
 

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interesting.
 

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MiniMan beat me to the punch but I'll leave this since I took the time to write it.

FYI, I work for a shop that installs them and sells them and I'm a believer. While their not right for every bike, if it's an older bike that you ride often and you rely on I believe it's one of the best steps you can do to have more ride time than repair time.

It's a lot more than a junction box. It's a micro processor with solid state fuses being just one aspect. The recently discontinued V.2 and new Blue models have all the following features while Blue has a bunch of new optional features involving synching with your phone via Bluetooth.

It removes voltage from the handle bar switches converting them into signal switches much like a computer keyboard significantly reducing the propensity for electrical failures at the handle bars.

It auto detects shorts, turns off the offending system and a light on the unit indicates where the fault is in the system and resets itself when the issue is resolved.

It's a sophisticated programable LED compatible turn signal relay.

It's also has programable brake functions and allows you use a 2 wire LED light as though it were a 3 wire Running light and Brake.

It has a built in alarm system.

Built in Starter relay, but not Solenoid*

Horn relay

and more, here's a link to the manual m-Unit Blue
 

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Think of it in terms of carbs to ECU on an engine
It's a BCU (bike control unit) rather than an ecu. It does everything for the bike using finely tuned electronics to make it reliable and better for everyday use rather than 40 year old electrics.
Plus if you get the option m-button you convert the system to canbus, which means that all handlebar controls are operated through 1 wire.
Reducing the amount of wires isn't just for aesthetics, the less wire means less joins which means less points for failure.
 

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No disrespect intended but I have to disagree with that statement. The m-button is actually very fragile and subject to any number of malfunctions and failures. It's extremely sensitive to EFI and can trigger functions you did not actuate. Often just one input wire will fail causing you to have to pull the entire component and all of your wiring vs just the one wire. There's no way to check continuity should you need to. And it's a hell of a lot more difficult to install that just running under a dozen 22 AWG wires tucked in sleeving through your bars, You can even use super small gauge multi conductor wire if you can source it.
 

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When I got them I always use shielding on the config wire.
This stops the rf interference.
I will agree that they are delicate if installed incorrectly say reverse polarity.
Thankfully the m unit is niegh on impossible to break with normal on bike voltages.
 

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so M-unit good, m-button bad?

honestly I am actually blown away with how impressive this tech is, at least how the m-unit is described.

I think the only problem I have is the expense. I can see this being easy to justify for a high end custom motorcycle from a lot of different standpoints, but for something like a $1500 cb750 honda the $350 cost provides a lot more value in the average ownership/use lifespan of a vintage bike. The one thing I like about old stuff is it is home reparable so despite being 40-50 years old I can still solder my starter switch to fix it, I can still rewire something with new wire, I can change a fuse box. If the M-unit fails 10 years from now what's my recourse? still will it be in better condition 40 years from now than my old fuse box?
 

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so M-unit good, m-button bad?

honestly I am actually blown away with how impressive this tech is, at least how the m-unit is described.

I think the only problem I have is the expense. I can see this being easy to justify for a high end custom motorcycle from a lot of different standpoints, but for something like a $1500 cb750 honda the $350 cost provides a lot more value in the average ownership/use lifespan of a vintage bike. The one thing I like about old stuff is it is home reparable so despite being 40-50 years old I can still solder my starter switch to fix it, I can still rewire something with new wire, I can change a fuse box. If the M-unit fails 10 years from now what's my recourse? still will it be in better condition 40 years from now than my old fuse box?
All very valid comments.
A crusty connected is easy and cheap to replace but a £150 electronic module not so.
I suppose it all depends on what you call expensive. It's all relative.
I don't think it's expensive for the level of sophistication but I certainly wouldn't want to replace it on a regular basis.
Only time will tell how reliable they really are.... I'm thinking German made and solid state so good.
However I bought a new mini (part of the bmw group) and that pos fell apart around me as I drove it...
 

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All very valid comments.
A crusty connected is easy and cheap to replace but a £150 electronic module not so.
I suppose it all depends on what you call expensive. It's all relative.
I don't think it's expensive for the level of sophistication but I certainly wouldn't want to replace it on a regular basis.
For what it is and does there is no dispute it is a good value technology wise. It's when you start to get into the ownership costs vs use of an old motorcycle that it becomes harder to justify. When I was riding my 75 cb750 every day I would gladly have paid for this if it had existed in the 1999-2011 time period, but it didn't now that I don't ride all that much how much $1 per mile is it going to return for me.


Only time will tell how reliable they really are.... I'm thinking German made and solid state so good.
However I bought a new mini (part of the bmw group) and that pos fell apart around me as I drove it...
Well they had to replicate the English experience with the mini somehow. I mean, would you have trusted it if it was a British badge and didn't make you curse the darkness when the lights failed? (I'm just kididng here)
 

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What's up Geeto, good to know you're still here sharing your wisdom.

Over all Motogadget produces the highest quality motorcycle components I've seen hands down. The two weak links in their offering is the m-Button which is problematic as stated above but is massively over hyped by people afraid to run 8 22AWG wires 3 feet and plug them into their corresponding terminals. The other is the m-Lock back up capacitor which simply doesn't work.

The philosophy in our shop is that systems should be as simple with as few variables as necessary so that it's as easy to diagnose as possible. The m-Button doesn't fit with in that perspective. If I were building a show bike that needed to run but would never be ridden and I wanted look so clean that it appears that there are no wires whatsoever, I would use an m-Button.

The tech is every bit as good as described. This is not the only solid state fuse block replacement on the market only the most advanced and well built currently available. If Motogadget should go by the wayside someone will pick up the slack because the demand is there. 40 years from now you'll be struggling to find a supplier for archaic glass tube fuses for your now 70+ year old fuse box. I do see your point and I don't disagree with it but see ing the market from the back side I believe that solutions will only become more readily available rather than less. My concern would be is the subject bike likely to become rare or valuable as an unrestored specimen 40 years down the road not that I think that's a real concern for most 70-80's CB's

And let me know where you can still get a $1500 CB750 in good order. Haven't seen one under $2500 in years in these parts. And I have to agree with you, 5+ years ago while the tech made sense the cost of an install outstripped the market value of 70's Japanese bikes but that market has changed dramatically in the last half decade depending on where you live. In Austin a shitty CB350 with clip ons and solo seat can get $3k. We're already well into the stage where CX500's are highly desirable when you couldn't give them away 15 years ago.
 

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What do you mean by "built in starter relay, but not solenoid"? Is it a high amp relay that replaces the solenoid....or would I still have to use a solenoid?

And yes, it's nice tech but what if the turn signal unit / something else fubars? - do I need to shell out another $350 for a new M unit?

I kind of like the idea of having separate components - I mean, I can get a LED flasher relay from China for about $1.....
 

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To me I just don't see the harnesses as a weak point on most vintage bikes.
youmare also talking to a guy that sees little point in an electronic ignition for a CB750 street bike.

my fear is replacing simple wires and systems with a "black box"
 

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To me I just don't see the harnesses as a weak point on most vintage bikes.
youmare also talking to a guy that sees little point in an electronic ignition for a CB750 street bike.

my fear is replacing simple wires and systems with a "black box"
Do you still have a phone with actual buttons by any chance haha.

In all seriousness these aren't for everyone.
A well maintained standard loom does the same job as on of these without the witchcraft.
Imo these come into their own when you have a bike were the p.o. fucked about with the wiring and there are gremlins everywhere. I hate unfucking other people's wiring Bodges.
 

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What do you mean by "built in starter relay, but not solenoid"? Is it a high amp relay that replaces the solenoid....or would I still have to use a solenoid?

And yes, it's nice tech but what if the turn signal unit / something else fubars? - do I need to shell out another $350 for a new M unit?

I kind of like the idea of having separate components - I mean, I can get a LED flasher relay from China for about $1.....
Some or most Motorcycles have a starter relay that redirects the high amperage so it's not flowing through your starter button before reaching the starter solenoid, in technical terms a solenoid is a relay, the m-Unit does not replace the starter solenoid.

What makes it nice tech is not just the features but the durability. Again, in 6 years and thousands of units sold I've seen maybe 4 broken m-Units 2 of which were destroyed by massive over charges that would have destroyed the entire electrical system otherwise but yes if the sky falls and the turn signal relay breaks and it's out of warranty you need to spend another $350.

With a $1 Chinese relay you get what you pay for. You simply can't get a relay with these features for $1 or $20 anywhere. If you're interested in having a comprehensive understanding here's M-Unit Blue Manual and like miniman said, this is not for everyone. If you like tracking brittle wires and cleaning corroded contacts on the side of the road at night is your idea of a good time because that's what you know then cool, the m-Unit's not for you. If you require consistency and reliability, like you and you're already thinking about rewiring the bike you might want to look into an m-Unit.
 
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