Tcsailer and the 81 XS650

[tcsailer]

Hello all, first time poster. I just got my 81 Xs a few days ago and have launched into a major project with it. I have worked on quite a few cars before but never a motorcycle and this is my first bike so I'm running into some confusions.

In trying to wire the M-Unit blue everything is relatively straight forward except I can't figure out what to do with the brown switched power line from the stator. It looks like it would normally power a lot of the electrical system, but since the M unit will be doing all of that I can't figure out what to do with it.

I've been working with the following diagrams to try to figure this out on my own. If anyone has any insight or advice it would be greatly appreciated.

 

[Jim]

The brown wire is power to the rotor, not the stator. On 80 and up bikes the rotor is powered and the regulator controls the ground through the green wire.
And welcome to the forum...

 

[Downeaster]

A bit more information and a bigger picture would help.

What is an "M Unit"?

 

[tcsailer]

The brown wire is power to the rotor, not the stator. On 80 and up bikes the rotor is powered and the regulator controls the ground through the green wire.
And welcome to the forum...

So as a man confident enough to admit my own failings, I'm only further confused by this comment

ultimately what would that mean for my rewiring project? If the red permanently hot wires are run fused to the the battery, are the brown wires then superfluous?

 

[tcsailer]

A bit more information and a bigger picture would help.

What is an "M Unit"?

An M unit is essentially an ECU. Run hot from battery to that then power is run from m unit to switch. On the other side power is M unit to device i.e. headlight, turn signals etc. It's a very cool piece of kit and simplifies wiring a lot. I am not however a master electrician nor do I totally understand how electricity works as a concept.

Also I cant figure out how to upload a larger image so here is a link to the m unit instructions. https://motogadget.com/shop/media/downloads/manual/munit_blue_manual_1.8_en.pdf

Diagram as linked above is on page 10

 

[Jim]

So as a man confident enough to admit my own failings, I'm only further confused by this comment

ultimately what would that mean for my rewiring project? If the red permanently hot wires are run fused to the the battery, are the brown wires then superfluous?

The red fused wire is the output power from the regulator to charge the battery. The brown switched wire is power from the batt (through the ignition switch) to power the regulator and rotor. No power on the brown wire means no charge. In other words, yes you need to power it.

 

[tcsailer]

The red fused wire is the output power from the regulator to charge the battery. The brown switched wire is power from the batt (through the ignition switch) to power the regulator and rotor. No power on the brown wire means no charge. In other words, yes you need to power it.

AHHH!! I understand now. I never considered there would be a power in line to the regulator. So in that case would there be any reason the brown wire couldn't be spliced into that red fused wire directly or would that lead to a parasitic drain? There are some ignition switched outputs on the M unit I could splice into otherwise

 

[Jim]

Here's a colorized schematic of the 80. Your 81 should be pretty close on the basic equipment.

 

[Jim]

If you tied the red and brown, the alternator would be powered all the time... draining your battery. The brown has to be switched from the ign. switch.

 

[tcsailer]

If you tied the red and brown, the alternator would be powered all the time... draining your battery. The brown has to be switched from the ign. switch.

Copy. I wired it to the aux 1 output with can be configured to power when the ignition is on. Thank you so much for explaining. I jumped in feet first to an overly ambitious project and don't regret it yet!

 

[Jim]

Copy. I wired it to the aux 1 output with can be configured to power when the ignition is on. Thank you so much for explaining. I jumped in feet first to an overly ambitious project and don't regret it yet!

Nothing wrong with bein' ambitious. You should consider starting a build thread. That way all your questions, answers and progress will all be in one place. Here's mine to give you an idea how helpful it is. Good luck... and we love pics. here.

 

[Jim]

You could even change the title of this thread and you have yourself a build thread.

 

[Jim]

Just watched the video on the M unit blue. That's a pretty slick setup....

 

[tcsailer]

Following Jim's suggestion figured I might as well make a bit of an impromptu build thread. I got the bike for a grand. headlight had a parasitic drain killing the battery. Tank was also a horrible rattle can blue. I figured I could work with that and pulled the trigger. Here is every photo I have taken with how it sits today as the last.

https://imgur.com/a/mlUuw5L

 

[Jim]

Nice lookin' bike. What's your plans for it?

 

[tcsailer]

gonna do a bit of a cafe/scrambler thing. got a tuffside seat coming in and the tank is going to be jaguar f type British racing green with an asymmetrical black stripe. should be done as soon as Friday. Not doing everything I want to do to it atm bc of time and money but we shall see where it goes.

 

[5twins]

Egads, you certainly did tear into it, lol. That looks like a complete Commando replacement exhaust, about $300 right there. By the way the headpipes have turned blue so far down their lengths, I'd say no carb re-jetting was done but needs to be. Probably just one up on the pilots and one or two up on the mains will do.

That front fender is off an earlier model and would've had front and rear stays. It might be quite sought after by an earlier model owner if the chrome is still good.

 

[650Skull]

M unit wiring diagram for a Points model XS650 by Member "Mosfet"
Link to his rewiring thread
http://www.xs650.com/threads/wiring...ier-regulator-not-a-nylon-screw-thread.39575/

 

[fredintoon]

Following Jim's suggestion figured I might as well make a bit of an impromptu build thread. I got the bike for a grand. headlight had a parasitic drain killing the battery. Tank was also a horrible rattle can blue. I figured I could work with that and pulled the trigger. Here is every photo I have taken with how it sits today as the last.
https://imgur.com/a/mlUuw5L

Hi tcsailer and welcome,
some things a new XS650 owner may not know:-
An XS650 STANDARD tank is a gallon bigger and drops right on.
Almost any style of disk front drum rear XS650 wheels are a bolt-on swap.
The stock post '76 front brake lever's piston is sized to work TWO calipers.
A lever with 1/2 the piston area really works better with a single caliper
but you gotta upgrade to stainless brake hoses.
The "search" button will find you details of 'most anything that has been
done to the bike by others by using the appropriate keyword.

 

[tcsailer]

Well I have been busy! Finsihed the tank paint. Got the seat in and welded on a seat hoop and battery tray. Got the M unit plugged in and working so far, haven't turned the bike over yet so still some questions there but certainly getting closer.

pics: https://imgur.com/a/mbGUqTv