Engine wiring. 1980 R65

[jg928s4]

I am reassembling my engine and need help getting the Diode Board and Alternator wiring correct.   Those that are following my escapades, I drove my bike to the shop for tune up, they found broken cam shaft were gear attaches so no timing.  I pick up bike with box of parts and pay $400....    now to reassemble I do not know how wiring goes on alternator and diode board.... have Clymer Manual, but not to helpful.

[georgesgiralt]

Hello !
Re-wiring the alternator is quite easy.
See the attached picture ....
It is said to be for the latest BMW but it is also good for your's.
P.S. I am NOT the designer of this wonderful picture. I saw it somewhere on the WEB.

[montmil]

The diagram is from the Rick Jones book, Classic Boxer Charging. This excellent "tool" belongs in every Airhead owner's toolbox. Got mine!

http://www.motoelekt.com/goodstuff.htm

[jg928s4]

Thanks, I saw that but being an 80 I was not sure.  And 3 wires going from alternator to diode board "any to any does not matter" ?  I know the spade connector I have can go 2 ways, so I guess it doesn't matter which way....?

[georgesgiralt]

Yes, it does not matter. Current going out into this wires is AC 3 phases and it goes into the rectifier where it will become DC. So it really does not matter.

[jg928s4]

I have a 4th black wire that comes down out of the harness from frame with the blue D+ wire and brown D- and black DF wire.  Any suggestions?

[Bob_Roller]

The three wires from the stator of the alternator, to the diode board, doesn't matter how they are connected to the diode board .

Maybe to clarify there are three wires, black in color, the same diameter, they go to U V W on the diode board, there is a slightly smaller diameter wire black in color, from the alternator stator, that goes on terminal  Y on the diode board .

[jg928s4]

I have the Y on Board to Y on Alternator.  But I have a black wire that comes down with the Blu wire that goes to the D+ on the Diode board and the 2 wires (brown D-  and black DF ) that go to alternator??

(corrected reply 5)

[Bob_Roller]

There are two .75 sq mm wires, one black and one brown that go to the alternator brush connections and it does make a difference which terminals you connect them to, the brown wire is a ground, or earthing wire, the black wire is the signal from the voltage regulator to the alternator .

The black wire goes to an insulated bolt on the alternator, the other is a direct path to ground, if you get them swapped, the alternator will not produce any power .

[jg928s4]

I must assume I have 1 extra black wire.   I do not see it in diagram in reply #1, it is short , same length as the blue wire.  The Black and Brown wires that go to D- and DF are proper length and clearly marked.  the short black and blue wires go up together to a plug, the plug goes into the harness.

[jg928s4]

per the 81 diagram it looks it needs to go to the starter motor, but I have a 80.   looking at the starter the wire is missing opposite the red.

[georgesgiralt]

Hello !
Is you black wire fitted with an isolated spade connector ?
If yes, check if the starter motor gets its command (it should have 3 wires on it : One huge cable (16mm², black) from the battery on the upper M8 (13 mm spanner) connection, one thinner (4mm², red) wire on the same connection coming from the diode board and this black wire coming from the same connector as the 0.75 mm² blue wire from the charging bulb (which goes to the D+ connection on the diode board)
If you leave this black wire unconnected, the starter won't spin lacking a command voltage !
If you need, I can scan the original BMW electrical schematics from my user manual. (my bike is a 1982 and should share the same wiring as yours in this area and everything else if yours is an electronic ignition one)

[Barry]

Maybe this diagram helps. I know it says R80 GS but all airhead charging systems are much the same. One difference is the 3 stator connections are shown black here where as you may find that your wires are different colours. It still makes no difference which way around the are connected. Everything else on the diagram should be the correct colour for your wiring.

sw = black

bl = blue

rt = red

br = brown

gn = green

[jg928s4]

Thanks,   Yes, it was the starter wire, and Bike starts and gen light goes off.   Interesting that my 79-80 schematic is different than the 82 schematic in my manual, but 82 is correct when shows starter wire and the blue and black wire going through same connector??

Now to re assemble covers and get it timed.

Thanks,

Jon