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Thread: I'm behind the front cover what to replace?

  1. #1

    I'm behind the front cover what to replace?

    78 80/7 16000 miles

    Points clean or replace?

    Can I trust the 40 year old circuit board above the alternator

    The wiring harness is stiff but intact. Common source of trouble?

    Thank you!

  2. #2
    Registered User toooldtocare's Avatar
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    Points wear, but they give warning when they are nearing the end of their life. Many people, including me have had good luck with aftermarket solid state ignition systems. My favorite is the Dyna Mk III. That said, a properly setup with points will run just fine. The diode board can fail from time to time, even when they were new. But, if yours is running and charging ok, Id leave it alone. There are aftermarket charging systems available that will give you more power and reliability, but Ive never used any. Wires get stiff, it is an old bike. Once you replace one thing, something seems to go bad next. I would fix the things broken and ride the bike to find out what the next thing that needs replacing.

    Wayne

  3. #3
    MOA #24991 Pauls1150's Avatar
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    I don't know if the 78s were involved, but on some of the diode boards, the solder fractured due to being the wrong mix (tin & lead).
    On others, the solder actually melted due to the current draw passing through the solder, instead of the junction of the bent diode lead to the circuit board.
    Last edited by Pauls1150; 07-31-2018 at 03:11 PM. Reason: cuz my spelchekr duznt wurk

  4. #4
    Liaison 20774's Avatar
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    Quote Originally Posted by Pauls1150 View Post
    I don't now if the 78s were involved, but on some of the diode boards, the solder fractured due to being the wrong mix (tin & lead).
    On others, the solder actually melted due to the current draw passing through the solder, instead of the junction of the bent diode lead to the circuit board.
    Snowbum seems to have covered this on this page:

    http://bmwmotorcycletech.info/trbleshootalt.htm

    It was the early 1980s and it was the Wehrle boards...short lengths of wire on the diodes that couldn't be bent over and soldered.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #5
    #4869 DennisDarrow's Avatar
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    If it aint broke......DONT FIX IT

    I know, an old saying but good advice. Why even touch it if it is working???......That's just me but on this older stuff, some, MOST, is just fine and is gonna work for a LONG time; but then when you go to messing with it, it becomes faulty.

    If the diode board is functioning, there are replacements that are better, yes, but for now, leave it be...….Whats the name of the fella that has been with us a long time???......Richard and Euro Electric or something like that....He advertises in the "BMWMOA news"...…

    Take a look at the face of the points.....are they pitted, marred, nasty looking???? Is there ail in the point "chamber"??? The condenser is one that needs replacement for sure if you are gonna do a whole ignition overhaul. WHAT'S THE NAME AND SUPPLIER OF THAT LITTLE TOOL HE CAN USE FOR SETTING POINTS THAT GETS THE ADVANCE UNIT OUT OF THE WAY???

    Just as an aside. I have gone hundred of thousands of miles on the stock points unit with only touching them up at the 10K maintenance intervals and replacement when they become worn out or burnt out due to condenser failure. These show up slowly but surely when performing maintenance over a couple of tune ups...…..GREASE THE CAM LOBE WHEN IN THERE

    Take a second, third, and fourth look at how to keep the ignition wire in place so that you dont crimp it when replacing the front cover...…….

  6. #6
    IMO, I would clean everything up, make sure all connections are cleaned and tight.

    Then just RUN it!

    But, there are several items in there that will likely go bad: the diode board and the points system.

    What I would do is keep your eyes open and prepare by looking for replacement stuff before your stock items go bad. I had the Dyna III and many people told me that when they replaced the points systems with the Dyna, the bike actually started easier and ran better. I think the company MotoElectric (I think) has excellent stuff, more reliable and less expensive than original stuff.

    I would just buy stuff by looking ahead and getting what you may need in the future. Follow threads on this forum, and you will see subjects come up that will give you heads up for future issues you may have.
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

  7. #7
    Registered User
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    Remember to disconnect the negative battery terminal before removing the front cover. Just in case you didn't already know that. Bump the cover against the diode board with the battery connected and you will need a new board.
    Steve

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