Wiring diagram, no spark

[rohde_d]

I am looking for a wiring diagram for a 1983 R65. If any one could point me to one online or one I could get faxed to me that would be great.
I am having  a intermitant problem with losing spark. Dosn't seem to matter if it is cold or hot, leaning or straight up. I replaced the coil with no help. Any suggestions would be great.

[nhmaf]

This link should bring you to a pretty good one, though we have on occasion found some
discrepancies with the wiring and colours depending on whether the model was a
european or usa-market model.
http://www.tannis.dk/bmw/bmw%20r65-2%20wiring.htm

I have both a Haynes and a Clymer manual - they don't always agree, but are often
close.  I have found some discrepancies in the Haynes book, but at least it does have
some nice color images of the wiring harness.

hope that this helps you,
Mike

[Bob_Roller]

Are you just losing just the ignition system, or is the entire electrical system failing? A common problem is no di-electric heat transfer grease between the ignition control unit (ICU) and it's heat sink. It's located under the fuel tank. What kind of condition are the ignition leads in? After that it's loose connections just about any where in the wiring harness.

[rohde_d]

Just spark, everything else keeps working. It will usually backfire after a few seconds and then restart. May run for 10 min. or ten days before it does it again.

[rohde_d]

Thanks loads!!!!!  nhmaf    That is great. At least I can see where everything goes now. It seems to be a wiring problem. I can make the spark come and go it seems anyway by moving the wires under the tank around. Just cant seem to isolate which one or make the problem duplicate. I did get it once to make a contineous spark. "How about that one".

[nhmaf]

Check the ground wires, as you probably suspect.  Since you can make this happen with moving the wiring harness around,
you may be losing an electrical contact (possibly ground) with an intermittent open circuit going from under the tank up to the handlebar/
ignition switch, or you might have an intermittent short occurring which is shorting out a 12V line.

We had a problem a bit earlier with another member with a slightly older model R65.  The coil mounting bracket had cracked and
the ground wire, which had been connected to the frame ground through the bracket, became intermittent.   Your bike is
a newer model and has a bit different wiring scheme, but it is a possibility.

Best of luck, and if you can give us any additional info, we'll try to help narrow things down.  You indicated that you replaced
the coil, can you tell us if you put in the BWM std coil, a used coil, a dyna brown coil, or ?   Did you replace a bracket or notice
any unconnected wires afterwards ?
 

[Justin B.]

Probably a broken ground as suggested but also make sure one of the coil primary wires isn't shorting out against the underside of the tank.

[rohde_d]

Well we unplugged all the plugs and did a visuall check. They all looked great. Inspected the harness for pinch  points and cuts and found none. Replaced the coil with a new one (BMW but slightly differant, a superseded part number). The plug wires look ok, don't know the resistance to check for on them. Pulled the ICU and cleaned the back as well as the mounting bracket and applied new dialectric grease. Cranked it over while moving the wires all around and could not get the spark to go away. Reassembled everything and started her up and it sounded great. Went for a test ride and about 4 blocks away it died. After a little cranking and a few back fires it restarted and ran back to the house. Same as before.

When it dies, it is quick, just like you flip the kill switch. All the lights stay on, the generator light comes on and sometimes the tach will jump. I am thinking my next move should be to replace the ICU?

[Justin B.]

Check the small wires going to the coil terminals.  Too bad you don't have a portable O-scope so you could check/monitor the hall-sensor output to see if it goes away as these are known to fail also.  Another connection to check would be under the front engine cover, the harness from the "bean-can" mates with the bike harness, check to make sure it is secure.  The connectors are latched together with a wire "bail" which is kind of a PITA and some (myself included) tend to leave off this wire when in a hurry.

[rohde_d]

First, let me thank everyone for all the help!! After much internet searching and a lot of sweat and head scratching it looks as if we have fixed it. After checking all the plugs and wiring we started replacing parts. Come to find out the electronic ignition parts on most of the R models are the same as well as on some Audi and VW cars (go figure). We put a amplifier from a Audi on and the problem stayed the same. Then as luck would have it a freind had a R100 and we swapped the Hall sensor from it and the problem went away.  YEE HA!!!!!!!!!  The wife is back in the saddle.
As a side note in my searching I found the BMW crowd to be most freindly and helpfull. The guys at MAX BMW in NY and the fellow at Beemer Bone Yard were very nice. I also found a site that was a very interesting read and had some great info you might want to check out.
http://www.cdegroot.com/cgi-bin/mirror/pweb.jps.net/~snowbum/index.html

Thanks again to everyone!

[Justin B.]

If it's not too painful to recall, how much did you have to give for the replacement bean-can?  Never heard of the "Beemer Boneyard" before and after looking them up I would have assumed they wouldn't have had any Airhead parts...  Cool!

[nhmaf]

The Beemer Boneyard is a good place to keep in mind - though they do generally seem to have
an inclination to having more flying brick parts than airhead bits.   My cousin bought a complete,
under 50K mile K100 engine with fuel injection system, airbox, etc. in good shape for less
than a rebuilt airhead transmission.   He's planning to ride it from Maine around the big lakes to
the rally this summer once bolted into his bike.

[Justin B.]

Just looking at their site I don't think I would have ever asked them about an Airhead part.  

[rohde_d]

If it's not too painful to recall, how much did you have to give for the replacement bean-can?
I have not bought one yet, just verified that that was it with the doner part from the R100. I think since we have the Audi that we stole the ampliphier from that I will try putting the Hall sensor from it as explained on the web site I gave the link to. There is a lot of info and it is time consuming to sift through but sounds like the guy tries to verify all of his information. I will let you know how it comes out.
The instructions for the "bean can" rebuild or at the following link.

http://www.deathstar.org/~flash/ig_trig.html

[Justin B.]

Interesting, I have read that the same sensor can be had from a VW or Audi, but new ones are also available.  Check out http://mysite.wanadoo-members.co.uk/robpages1/Pages/vane_switch_tester.htm for more info.  Rob is pretty sharp when it comes to Boxer electrics and I think the sensor is under $20 for a brand new one.