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Thread: Brutal Starting Issue- 1983 R80 GS

  1. #16
    Thanks for letting me know that. I just took it back to the store and they replaced it. Hopefully the new battery will solve the problem. If not, on to the next hypothesis.

    Quote Originally Posted by PAS View Post
    My PC-680's show at least 12.84 when fully charged. Odyssey will replace it IF you have proven to charge it correctly and it fails. (Just my opinion)
    http://www.odysseybattery.com/documents/US-ODY-OM.pdf

  2. #17
    Day Dreaming ... happy wanderer's Avatar
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    Issues with Odyssey batteries are pretty much always due to lack of understanding how and why they are different. Everything you need to know is on their website but no one seems to read all that information. It's quite a bit to read actually but this is quite the battery and not a typical AGM. It is a heavy duty MilSpec AGM battery with great capacity and a very long life if treated properly. And BMW bikes do not charge the Odyssey to the voltage they specify unless you modify your charging system.
    Some notes:
    - A battery tender is just that; a tender. NOT a charger. So if your battery is discharged a tender is not going to charge it properly and especially not an Odyssey battery. Their charge algorithm calls for a constant voltage charge with current limited to 7AMPS. As the battery voltage rises the current decreases until it reaches 14.7VDC which is a full charge. A battery tender cannot do this.
    - In order to know if your battery was good or not, load testing it after a full charge with an approved Odyssey battery charger is the only realistic way to test it. You can get a load tester at harbour freight cheap.
    - The Odyssey battery requires a high rate of charge (My Odyssey charger puts out 7AMPS) and an end voltage of 14.7VDC. Most standard auto chargers do not go this high and stop charging at 14.2 which leaves the Odyssey at less than a full charge. When not fully charged lead acid batteries which is what an AGM battery is will sulfate and this leads to failure.
    - If you want your Odyssey battery to charge properly and fully in an oilhead you need to modify the alternator output diodes or do as I do and recharge it fully when you get home from rides with an Odyssey approved charger. I have over 8 years service in my 1100 doing just this and leaving the alternator stock. If you want to charge it fully onboard an airhead get a digital adjustable voltage regulator and dial it up to 14.7 VDC to keep your Odyssey fully charged. You can get one of these at Euromoto Electric and from Rick Jones at Motorrad Electric and they are not expensive and easy to install and dial in.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  3. #18
    Everything Michael just wrote is absolutely correct. That said, it fails to account why a battery would have as large a voltage drop overnight or in 24 hours as was tested by the OP.

    I have an Odyssey I keep on the bench for electrical testing and somesuch. I don't worry about it being peaked out over 14 volts and it still only drops a few 100ths volt in any 24 hour period. It took 14 hours to pull down to 4v with a headlight bulb attached.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  4. #19
    Looks like it was a faulty battery. I swapped it out last night for a new one and things are now working fine. But... Now the bike won't turn over even though it sounds like it has a strong charge. Based on what I've read, assuming it must be a gas/air/plugs issue with either the carbs or the spark plugs.

    Quote Originally Posted by PGlaves View Post
    Everything Michael just wrote is absolutely correct. That said, it fails to account why a battery would have as large a voltage drop overnight or in 24 hours as was tested by the OP.

    I have an Odyssey I keep on the bench for electrical testing and somesuch. I don't worry about it being peaked out over 14 volts and it still only drops a few 100ths volt in any 24 hour period. It took 14 hours to pull down to 4v with a headlight bulb attached.

  5. #20
    Liaison 20774's Avatar
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    Quote Originally Posted by armartel View Post
    Now the bike won't turn over
    What does that mean? You hit the start button and the starter doesn't even turn?? Or do you mean the engine won't catch and start when you hit the button?
    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!

  6. #21
    The starter turns, but it won't catch and start when I hit the button. Checking the spark plugs this evening for a spark. Anything else topical I should be evaluating? Obviously, checking to make sure fuel is on.

    Quote Originally Posted by 20774 View Post
    What does that mean? You hit the start button and the starter doesn't even turn?? Or do you mean the engine won't catch and start when you hit the button?

  7. #22
    Registered User Anyname's Avatar
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    It's always worth checking the valve clearances. If any are too tight it can make a motor hard to start.
    BMW R bike rider, horizontally opposed to everything...

  8. #23

    Update

    Quick update here: I spent the last three hours testing different points on the bike. I found that there was no spark on either plug when removed, so that led me on a hunt which brought me to a 100% bonehead move. I had removed the front cover on the bike to take a look and when I replaced it, I pinched the wire on the Ignition Sensor wiring harness and cut the current. Stupid, stupid, stupid. I rejoined the wires and, of course, bike starts fine. The rejoining of the wires is a hack job because it was close to the end of the harness. Anyone know if those harnesses are replaceable (https://www.shopbmwmotorcycles.com/p..._parts_color)?

    Quote Originally Posted by Anyname View Post
    It's always worth checking the valve clearances. If any are too tight it can make a motor hard to start.

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