1976 R75/6 Troubleshooting

[Duane Ausherman]

I have mostly been staying out of this one. Jimijam, your approach is going to frustrate you and cost a lot. You need to proceed in a logical manner with understanding and knowledge of how to use the tools.

You said, "Ok so when I hit the ignition, nothing happens. How do I troubleshoot the starter ?"

You are a long way off from thinking about the starter. That is just about the least likely part to fail. Follow Ken's advice and work carefully. Did you jump across the starter switch to prove that the switch isn't the problem? All of this can be tested and proven.

Did you go to my article on this very issue? Why not? It is http://w6rec.com/duane/bmw/starter/

[Ken in Oklahoma]

This thread brings to mind Robert Pirsig's book, Zen and the Art of Motorcycle Maintenance; and especially his notion of the Classic and Romantic approaches to motorcycle maintenance. I'm not making any direct comparisons, but implicit comparisons to the stuff of this thread come to mind.

Trivial note: Back in the day, I was a young engineer working for Texas Instruments. A friend brought me a copy of Pirsig's book. He knew I liked motorcycles and he thought I might enjoy it. Reading the book changed my life. I don't mean to say it so dramatically, but after reading the book I never thought about motorcycles or the value of personal inquiry the same way again.


Ken

[chasbmw]

The 2 red wires which meet at the starter relay are the source for approx 50% of all airhead electrical problems.

Examine the wires and check for carrosion, worthwhile to replace a couple of inches of wire + connectors.

[ME 109]

Did you go to my article on this very issue? Why not?

For the same reason he didn't go to my article on this very issue. He didn't know it existed.
Wait a minute, I don't have an article on this issue.
No wonder he didn't go to it.

ME 109, fighting off kangaroos while hurriedly writing an article.

[Jimijam]

Ok so the instrument cluster is fully lit when key is turned, the main headlight is out(and not due to the bulb), nothing happens when you hit the ignition button. I'm just learning as I go . thanks for your patience. I got a multimeter, tested 12v at the starter solenoid. I hotwired the starter and it worked, could hear the pistons moving nicely. I could not come up with voltage at the relay. I apologize in advance for my ignorance.

[melville]

Ok so the instrument cluster is fully lit when key is turned, the main headlight is out(and not due to the bulb), nothing happens when you hit the ignition button. I'm just learning as I go . thanks for your patience. I got a multimeter, tested 12v at the starter solenoid. I hotwired the starter and it worked, could hear the pistons moving nicely. I could not come up with voltage at the relay. I apologize in advance for my ignorance.

OK, here we go! I had entirely too much fun making my own /6 run, and now you can benefit from my misadventures:

viewtopic.php?f=1&t=148&hilit=woo&start=125

That should put you right close to the "starter relay" section of my odyssey. The wiring diagram, while not right for either of our bikes, should give you the basic overview of how BMW wires the starter system.

First, a couple things:

Key should be on, lighting up the idiot lights.
Kill switch should be in the middle position. Up or down is off.
Trans in neutral, blue light on at the instruments. Pull the clutch lever as well if you like.

Try that.

[Ken in Oklahoma]

Ok so the instrument cluster is fully lit when key is turned, the main headlight is out(and not due to the bulb), nothing happens when you hit the ignition button. I'm just learning as I go . thanks for your patience. I got a multimeter, tested 12v at the starter solenoid. I hotwired the starter and it worked, could hear the pistons moving nicely. I could not come up with voltage at the relay. I apologize in advance for my ignorance.

Good for you Jimijam. I'm not sure what you mean when you say, "I could not come up with voltage at the relay." If you're referring to the the 12V that appears at one of the relay pins as the result of pressing the starter button, it should be there. I don't have any wiring diagrams handy so I can't be specific as to what pin would be involved. In any event, if such is the case, the problem becomes why isn't the 12V appearing when it should? That would involve looking at the wiring diagram and figuring out how the 12V is supposed to get to the pin, and then testing to find out where it gets lost.

There is another concern with the starter relay and the socket it plugs in to. The area where they are located (on the L/H side of the frame top tube) is just under the under-the-tank master cylinder. Many if not most /6 and /7 bikes have experienced a leaky master cylinder at some time in their life, and brake fluid has found its way to the relay socket. You will see two fairly thick red wires going to the relay socket. That "pair" is the "hot" wire that goes into the headlight shell to power virtually all of the electrics in the motorcycle. Those two red wires are connected together via a hard wired connection inside the relay that plugs into the socket. Often, because of crud in the socket, the pins didn't make good contact with the mating female pins and the bikes electrics are dead. No lights will light in the instrument cluster with the ignition key on. This happened to me on my '77 R100/7 and is a known problem that can occur.

If that should be your problem the solution is to remove the starter relay from the socket and thoroughly clean the relay pins and the socket pins. The latter is easier said than done since the relay socket pins are hard to get at. Electrical contact cleaner (available at auto parts stores) is used with a tooth brush and elbow grease.

As an aside, the reason that I've heard for the Mickey-Mouse arrangement of the relay connecting the two red wires in the harness is because BMW wanted to simplify (and cheapen) the wiring harness by making it in two pieces. Makes sense from a production standpoint, but I doubt if BMW ever considered much what might happen, say, 10 to 20 years down the road. (In fairness I don't imagine any manufacturer being terribly concerned about what happens 10 years down the road.)

Another thing that could be done, which I didn't do, but probably will do if the problem recurrs is to simply skin back some insulation from the red wires at the socket and (properly) solder a connecting wire between them. Of course the close quarters make that "solution a bit fiddly too.

Ken

[Jimijam]

I have mostly been staying out of this one. Jimijam, your approach is going to frustrate you and cost a lot. You need to proceed in a logical manner with understanding and knowledge of how to use the tools.

You said, "Ok so when I hit the ignition, nothing happens. How do I troubleshoot the starter ?"

You are a long way off from thinking about the starter. That is just about the least likely part to fail. Follow Ken's advice and work carefully. Did you jump across the starter switch to prove that the switch isn't the problem? All of this can be tested and proven.

Did you go to my article on this very issue? Why not? It is http://w6rec.com/duane/bmw/starter/

I am but a young padiwan learner where as this forum the Jedi council ! My Dad Fred has been doing most of the work here, but is computer illiterate so I'm just trying to middleman some knowledge while gaining a little understanding.

[Ken in Oklahoma]

I am but a young padiwan learner where as this forum the Jedi council ! My Dad Fred has been doing most of the work here, but is computer illiterate so I'm just trying to middleman some knowledge while gaining a little understanding.

Urban Dictionary: padawan
http://www.urbandictionary.com/define.php?term=padawan
1 A Jedi pupil or student, or broadly used as anyone that is learning 2 A nickname used, often demeaningly, on someone trying to be as good as you ...


Jimijam, do let us know if you ever learn the Jedi technique of planting thoughts in somebody's brain; thoughts they think are their own. I could have really used that trick in my teen and early adult testosterone addled years.

It may not be too late even now. More difficult maybe, but not too late.

Ken

[melville]

I am but a young padiwan learner where as this forum the Jedi council ! My Dad Fred has been doing most of the work here, but is computer illiterate so I'm just trying to middleman some knowledge while gaining a little understanding.

Urban Dictionary: padawan
http://www.urbandictionary.com/define.php?term=padawan
1 A Jedi pupil or student, or broadly used as anyone that is learning 2 A nickname used, often demeaningly, on someone trying to be as good as you ...


Jimijam, do let us know if you ever learn the Jedi technique of planting thoughts in somebody's brain; thoughts they think are their own. I could have really used that trick in my teen and early adult testosterone addled years.

It may not be too late even now. More difficult maybe, but not too late.

Ken

My Muriel has that skill, but she's not sharing it. So many things go her way, and I'm convinced in the end that it was my own idea.