R65 Electrical Sin

[tlangman4]

Forgive me Father Beemer for I have sinned…

I should have know better, but I did it anyway. Finally started working on the ‘80 R65 that I purchased a while back. The bike sat in a garage for over 20 years after the owner passed away.

After stripping sheet metal off, I hooked up the new battery I had purchased to check the electrical system. Sure enough, the panel lit up as it should. Briefly pressing the starter button with plugs out confirmed power to the starter.

Then I failed.

Something caught my eye with the rear coil, and I started fidgeting with it. Convinced there was an issue with a connection, I loosened the mounting bracket of the coil until the coil fell out. Of course it touched a number of other electrical connections as it fell..

It was at this moment I realized I had accidentally left the battery connected and the main key switch in the “on” position..

Yep, everything dead.

There was no noise, no smoke, no indication of electrical failure. But dash light, etc., all dead.

Over the years of messing with my ‘70s Honda’s, it’s usually a matter of swapping out the main fuse near the battery when such nonsense occurs. No such luck on an airhead.

I have a large schematic of the electrical system, along with a big fat Clymer’s manual as resources. Yet nothing to guide me on correcting this fatal error.

Before I begin poking wires in search of Direct Current and making a bigger mess, I would appreciate suggestions on how to begin navigation of a repair in a proper progressive manor.

Thanks to all with suggestions on a process, as I beg for absolution. I truly should have known better to mess with anything electric with the batter still connected.

 

[20774]

Clearly you should find and check the fuses. Eventually, you'll probably have to an extensive visual inspection of wires and bundles followed by tracing power through the main circuits. Years ago when I also did something foolish, I ended up finding that the kill switch had been burned out. It was so long ago, I don't know how I got to that point. To "fix it", I wired in some kind of switch to bypass the handlebar switch. It's going to be difficult for me to remember/find that switch if/when I need it. I also have to tell the shop about it..."don't touch the kill switch!"

Start on the easy stuff and work up from there.

 

[tlangman4]

Clearly you should find and check the fuses. Eventually, you'll probably have to an extensive visual inspection of wires and bundles followed by tracing power through the main circuits. Years ago when I also did something foolish, I ended up finding that the kill switch had been burned out. It was so long ago, I don't know how I got to that point. To "fix it", I wired in some kind of switch to bypass the handlebar switch. It's going to be difficult for me to remember/find that switch if/when I need it. I also have to tell the shop about it..."don't touch the kill switch!"

Start on the easy stuff and work up from there.

Thanks! I should have mentioned.. yes, I did check the fuses under right side cover, first thing. Both good. I realized right after the coil fell from my hand that I left the switch on and battery still connected. Never touched the kill switch. Wish it was that easy..

 

[20774]

Thanks! I should have mentioned.. yes, I did check the fuses under right side cover, first thing. Both good. I realized right after the coil fell from my hand that I left the switch on and battery still connected. Never touched the kill switch. Wish it was that easy..

I never touched my kill switch either, but stuff happens. There is a path that the current flows and the kill switch became the sacrifice in my case. Just saying you have to following the circuit to find out what's failed.

 

[r0ckrat]

It should be fairly easy to check "weak points" for operation - using a multi-meter for continuity checks where there should be, and that switches function like switches (again for continuity or lack thereof when switched to the "off" equivalent)?

 

[skibum69]

What's that electrical thing just under the front cover that's always live and if you leave the battery connected when you pulll the cover you short it out? Maybe that was toasted?

 

[stevenrankin]

The diode board is under the front cover. It has a heavy positive wire running to it that can touch the engine cover when you are removing it. That is why you disconnect the negative or ground before removing the front cover.

Oh man, I get you are in a pickle.
I would start with the starter relay under the gas tank first. Check the connections to that for damage. If you have a spare, swap it out.
I have found the relay to be a weak link in the BMW system. They are not very robust.
After that if you don't find the problem there, go over the rest of the system. I have found the BMW wiring to be pretty robust overall, and have always been surprised there was never a master fuse installed. That means the system for the most part can take a minor short without damage. The exceptions being the diode board which can weld itself to things, or the starter relay. You would know for sure if the diode board failed. The relay not so much.


Where are you at? if close to Rochester NY, I can give you a hand. If I can't help I know an airhead shop. Good hunting, St.

 

[mohler]

You said, "Briefly pressing the starter button with the plugs out" Were the plug wires on the plugs and plugs grounded to the motor somehow while doing this? It's been awhile since owing a airhead, but I seem to remember that if the plugs are not grounded while using the starter it can do some damage to the electrical system.

 

[olironrider]

Newfoundland and Labrador, Canada

 

[stevenrankin]

On the BMW bikes with factory electronic ignition, trying to run the bike without the spark plugs grounded has been known to pop the ignition module. I am not sure but I think the 80 R65 may still have had points. St.

 

[tlangman4]

The diode board is under the front cover. It has a heavy positive wire running to it that can touch the engine cover when you are removing it. That is why you disconnect the negative or ground before removing the front cover.

Oh man, I get you are in a pickle.
I would start with the starter relay under the gas tank first. Check the connections to that for damage. If you have a spare, swap it out.
I have found the relay to be a weak link in the BMW system. They are not very robust.
After that if you don't find the problem there, go over the rest of the system. I have found the BMW wiring to be pretty robust overall, and have always been surprised there was never a master fuse installed. That means the system for the most part can take a minor short without damage. The exceptions being the diode board which can weld itself to things, or the starter relay. You would know for sure if the diode board failed. The relay not so much.


Where are you at? if close to Rochester NY, I can give you a hand. If I can't help I know an airhead shop. Good hunting, St.

Great info, Steven! Thanks! After reading your comments and studying the wiring diagram, I have located the starter relay. Seems a very logical place to start.
I’ll let you know how that progresses.
I am located in Cheeseland (WI). Wish it was a lot closer to Rochester..!
Thanks for the offer!!

 

[tlangman4]

I never touched my kill switch either, but stuff happens. There is a path that the current flows and the kill switch became the sacrifice in my case. Just saying you have to following the circuit to find out what's failed.

Great point..! I will get a look at the switch as well. Thanks.!

 

[stevenrankin]

Without obvious signs of damage like smoke and light, tracing things down Smith be hard. The black wires for ignition system would be the first place I would check after the relay. St.