The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: razz2234 on July 12, 2009, 10:23:08 AM
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I have a 1981 BMW R65...it's a new bike for me and I'm not familiar with it at all. I was told that I blew my diode board and need a replacement. I purchased one from Thunderchild and have not received it yet. Can someone tell me where I might find the diode board on the bike? Is it under the front cover by the Gen/Alt? I have the wiring diagram I got online from Thunderchild but I have to locate it first. Sorry, new to this.
Thanks
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The diode board is under the front engine cover .
Also remove the ground cable from the battery, there are 'hot' connections in there, electrical connections that have 12 vdc to them all of the time, and you can get a 'shower of sparks ', and damage I think the diode board, but that's not a real issue with you.
What kind of charging system problem do you have ?
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Welcome aboard!
Yes, it is under the front engine cover - be SURE to DISCONNECT the battery cables first on this and all future front cover removals to avoid accidentally shorting things out under there while removing the cover - this has caused many diode board failures in the past !
You might have to remove or loosen the exhaust headers to get the cover out of there - do you have an exhaust nut (those big finned things that screw on to the front of the cylinders) wrench? If you do have to remove them - One also has to be careful with those as the threads on the heads tend to gall/bind with the exhaust nut threads. The key thing to remember with those is to use the exhaust nut wrench, but if it starts to turn and then seems to get hard to turn again/tighten up-> STOP! You'll likely have to then use a hacksaw or dremel cutoff wheel to carefully cut mostly through the nut(s) and break them apart to avoid damaging the threads on the heads. The exhaust port threads on the heads can be repaired by skilled machine shop, but it is an expensive thing you don't want to undergo unless you have to. To prevent these threads from galling&binding in the future, I regularly (1x or 2X per year) carefully unscrew the exhaust nuts and put the silver Permatex anti-seize on the threads.
[Edit: You probably won't need to remove the headers if you've got the standard R65 exhaust - for some reason I was thinking of the later RT models exhaust with higher crossover]
Probably more info than you wanted - but just trying to help!
These are fairly simple machines to work on - but they are designed in a rather "odd" and old fashioned way which makes them both a joy and a challenge to work on as compared to modern Japanese machines!
:)
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1) Remove the battery ground strap located on the transmission, right-side- adjacent the speedo drive cable. As Bob and others will share with you, the diode board has some electrically "hot" spots that can come into contact with the front engine cover.
2) Are you positive the diode board is dead?
3) Buy one or both of the R65 shop manuals. They will guide you through some simple bits and inspire your confidence.
IMHO, I would not install the T'Child until confirming you really need it.
Monte