Need help with '75 Commando Mark III Electric Start

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Arlen Johnson

Arlen Johnson

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Hello to everyone. I'm a new member as of today. Due to a recent death in my wife's family I am now the proud owner of a 1975 Commando 850 Mark III Electric Start. I'd like to get it running and back to it's stock configuration. Fortunately it's 99% complete and it looks like it won't take too much to get it running. Mechanical things are no problem for me, but when it comes to electrons I'm pretty weak. Is there anyone out there that would be able and willing to step me through the process of sorting out the electrics on this bike? I just recently finished getting one of the deceased's Moto Guzzis running with help from a great guy only known to me as "guzzisteve" on the wildguzzi.com website. I'm hoping to get just as lucky with someone (or several) on this website.
 
Arlen Johnson said:
Hello to everyone. I'm a new member as of today. Due to a recent death in my wife's family I am now the proud owner of a 1975 Commando 850 Mark III Electric Start. I'd like to get it running and back to it's stock configuration. Fortunately it's 99% complete and it looks like it won't take too much to get it running. Mechanical things are no problem for me, but when it comes to electrons I'm pretty weak. Is there anyone out there that would be able and willing to step me through the process of sorting out the electrics on this bike? I just recently finished getting one of the deceased's Moto Guzzis running with help from a great guy only known to me as "guzzisteve" on the wildguzzi.com website. I'm hoping to get just as lucky with someone (or several) on this website.
Click to expand...

Welcome Arlen.
Be a little more specific on what exactly your problem(s) is and then stand back and watch how much help this supurb forum is willing to step up with advice.
Mention where ypu live and maybe someone close by could help.

Ride On
Dave
 
Arlen Johnson said:
I just recently finished getting one of the deceased's Moto Guzzis running with help from a great guy only known to me as "guzzisteve" on the wildguzzi.com website. I'm hoping to get just as lucky with someone (or several) on this website.
Click to expand...

you hit the jackpot

cheers
 
Electrics are very basic on a commando, what's the problem with yours?
Cheers
 
Arlen Johnson said:
Mechanical things are no problem for me, but when it comes to electrons I'm pretty weak. Is there anyone out there that would be able and willing to step me through the process of sorting out the electrics on this bike?
Click to expand...



One important thing to be aware of is the standard electrical system is positive earth/ground.


Workshop manual (wiring diagram, section J):
http://britmoto.com/manuals/Manuals/850_man.pdf
 
As noted, there is plenty of help available here. Is there a specific electrical issue that you are trying to sort out or are you just wanting to generally "go through" the system to ensure everything is working correctly? If the bike has been essentially untouched for years, some elec maintenance will probably be necessary. That would include cleaning all the bullet connectors to ensure good electrical contact and adding a ground wire from where the battery cable connects to the frame to a point on the engine itself. Sketchy ground connections on the Norton are often a source of odd electrical issues so they are a critical item to check. It is possible that a new wiring harness may be necessary if the original has been chewed up by creatures over years of storage! ;) Some folks make up there own harness; the OEM harness contains a lot of wires you won't use because it was designed to work with all Commandos, including police models which had a lot of accessories that are not used/need on a "normal" bike.

Welcome!
 
Before you attempt to start it... STOP.
Read.
There is significant wisdom to recommend pulling the exhaust rocker covers, and put a few ounces of engine oil in there to drain down on the lifters & cam after a long dry spell. Quick, easy insurance.
Welcome to the most in depth Cdo resource available.
 
sounds like you may have tried starts & not have much luck with the electric starter (maybe seems weak?) then the same no start results with kickstarting?

did you check for spark?

what carb(s?) are on the bike?

how long has the bike not started?
 
MexicoMike said:
adding a ground wire from where the battery cable connects to the frame to a point on the engine itself.
Click to expand...

As it is an electric start 850 Mk3 then it should already have a heavy-gauge battery (positive) cable connected to the engine.

The fitting of any secondary "battery ground wiring" should be avoided on an electric start model (unless the wire is fused) due to the potential for the starter motor current to use the light-gauge wire as the return to the battery.
What the Mk3 needs and should already have is a harness return connection to the engine (head steady, so the complete electrical system must use the heavy positive cable for the final battery 'return' stage.

The factory made the mistake of including a secondary light-gauge positive (red) battery connection (ring terminal) in the harness and this is also shown on the wiring diagram but it should not be connected if the starter motor is operational.

Need help with '75 Commando Mark III Electric Start




MexicoMike said:
the OEM harness contains a lot of wires you won't use because it was designed to work with all Commandos, including police models which had a lot of accessories that are not used/need on a "normal" bike.
Click to expand...

Unlike earlier models the standard 850 Mk3 harness contains very little 'additional' wiring.
 
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Sorry to hear of your wife's loss, I'm sure the bike will serve as a happy memory in that respect.

Looks like you've got a good start to go on, a decent shop manual is a big part of the puzzle.

Several POTENTIAL weak links in a MkIII e-start system are dirty/loose cables, dodgy starter button, sprague clutch in the primary drive whose teeth can fail, and incorrect tension on the anti-backfire clutch. All are detailed in the shop manual. Original Lucas starter solenoids have a finite life, also.

Let us know how you get on...
 
Arlen Johnson said:
Hello to everyone. I'm a new member as of today. Due to a recent death in my wife's family I am now the proud owner of a 1975 Commando 850 Mark III Electric Start. I'd like to get it running and back to it's stock configuration. Fortunately it's 99% complete and it looks like it won't take too much to get it running. Mechanical things are no problem for me, but when it comes to electrons I'm pretty weak. Is there anyone out there that would be able and willing to step me through the process of sorting out the electrics on this bike? I just recently finished getting one of the deceased's Moto Guzzis running with help from a great guy only known to me as "guzzisteve" on the wildguzzi.com website. I'm hoping to get just as lucky with someone (or several) on this website.
Click to expand...

WOW!! I had no idea I would get so many responses so quickly! Thanks!!! It looks like I won't have any trouble sorting out the electrics on my Commando.

OK, first some forum etiquette questions. Should I respond to the first reply only, but answer the questions all the responding members posed; or should I reply to each member individually?
 
Arlen Johnson said:
OK, first some forum etiquette questions. Should I respond to the first reply only, but answer the questions all the responding members posed; or should I reply to each member individually?
Click to expand...

However you like.
 
The Buckeye Rider said:
Welcome Arlen.
Be a little more specific on what exactly your problem(s) is and then stand back and watch how much help this supurb forum is willing to step up with advice.
Mention where ypu live and maybe someone close by could help.

Ride On
Dave
Click to expand...
I live about 25 miles northwest of Minneapolis, MN. I would like to post some photos. What's the easiest/best way?
 
It turns out the bike has an updated electronic system; that’s good! The Boyer box connections are as follows: The red wire splits, one goes to frame ground, and the other goes to the plus (+) terminal of the left side spark coil. The black wire goes to the plus (+) terminal of the right side spark coil. The white wire goes to terminal three (3) on the indicator light panel at the handlebar. The white on black and yellow on black wires both go to the old points/condenser area. Does this all seem correct?

Did the original factory setup have a positive ground, but the new electronic system has a negative (-) ground?


Need help with '75 Commando Mark III Electric Start


Need help with '75 Commando Mark III Electric Start


Need help with '75 Commando Mark III Electric Start
 
The Buckeye Rider said:
Welcome Arlen.
Be a little more specific on what exactly your problem(s) is and then stand back and watch how much help this supurb forum is willing to step up with advice.
Mention where ypu live and maybe someone close by could help.

Ride On
Dave
Click to expand...

See my recent post 12:04 CDT
 
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