1985 r80rt chargeing prob in Mexico

Discussion in 'Airheads' started by Tagman, Nov 4, 2011.

  1. Tagman

    Tagman JCunningham San Carlos, Mexico

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    I have a 1985 R80RT that just wont charge in Mexico and I can't figure this out. First time was 5 yrs ago rideing thru Mex in 115 deg temps, the elect system would only put out 12. 5 V. Return to Colorado at 7500 ft and all was fine, 13.6 V. The next year same thing, 2 days of rideing and no start without a charge, return to Colorado alls well. Next year same thing, charge every 2 days. Now I have moved down here and it's time to fix this, today the gen light came on at 60mph for the first time, stayed on for 15 min at speed, I revved the motor and light went off but still only 12.6 across the battery terminals at 3500 rpm. What should I check first? Any suggestions?
    #1
  2. Beater

    Beater The Bavarian Butcher

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    Just to start, I'd have a look at the brushes ... then the stator / rotor. Just a guess though ...
    #2
  3. Airhead Wrangler

    Airhead Wrangler Long timer

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    Try swapping in a good voltage regulator if you have one. Check resistance on your rotor, check continuity (or lack thereof) accross diodes. Just curious, what part of mexico??
    #3
  4. Tagman

    Tagman JCunningham San Carlos, Mexico

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    we are in San Carlos, Sonora Mex, I will pull the cover and test tomorrow when the bike cools down. Thanks
    #4
  5. supershaft

    supershaft because I can

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    What to start with? That is easy. ALWAYS start with the battery. What is the voltage drop when you hit the starter?
    #5
  6. Tagman

    Tagman JCunningham San Carlos, Mexico

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    I do have an Oddessy gel battery thats 3+ years old, it takes a good charge from my trickle charger in about 4 hrs but I would think I would still get a 13+V reading at the battery cables at about 3k rpm even if the battery was bad. ?
    #6
  7. lamotovita

    lamotovita Ageing Adventurer

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    If the bike has the original fuses replace them. They can oxidize slightly and develop enough resistance to cause the problem your having.
    #7
  8. Tagman

    Tagman JCunningham San Carlos, Mexico

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    I bought this bike with 20k, it now has 40k, I'm sure the fuses are the origionals, I'll give it a shot.
    \
    #8
  9. supershaft

    supershaft because I can

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    Not if the battery is bad. Static batt voltage means almost nothing. Many a bad batt will show 13 plus just sitting there. What's the voltage drop to when you hit the starter button?
    #9
  10. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Most people think batteries are a simple thing, but they're not. Watch out for stuff that SEEMS simple! :evil

    We had one thread here that must have gone for fifty pages, and in the end it turned out to be the battery. For years after, the running joke whenever any kind of problem arose (electrical or not) was to answer "it's the battery!"

    But you never really know till you check out the battery! It can appear to be fine, but really isn't. And you'll knock yourself out looking for the problem, and drain your bank account filling the shelves with expensive spares, only in the end to discover it was the battery.

    You can remove it and have a battery shop check it, or you can do a load test yourself with it in the bike. All you have to do is see what the battery voltage drops to when the engine is cranking. If it's nine or ten volts, it's ok. Anything less and it's questionable.

    Electrical stuff changes with temperature. It's normal for the voltage regulator to regulate differently in cold than heat. It's cheap, and easy to swap. After the battery that's where I'd look next.

    I don't suspect the rotor. Brushes maybe...
    #10
  11. Tagman

    Tagman JCunningham San Carlos, Mexico

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    Problem solved, 4 yrs ago my son bought a 89 gspd, elect system not charging. We bought an omega board to replace his, installed it and could not get it working. So to get him back to college on time we took the stock system on my bike and installed on his. After he left I installed the omega board on mine and it worked fine. Well I removed the omega board and 3 of the 4 mounting points that create the ground were totally melted away and the 4th made no ground contact until touched with a screwdriver. I wired a new ground directly to the block from the board and all works perfect now. Thanks for all the help, John
    #11
  12. Tagman

    Tagman JCunningham San Carlos, Mexico

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    Took it out for a real nice ride with the wife today, It was not even dropping below 12.5V idling at Guymas Mexico stoplights (very long lights, very hot). At speed the meter was acting normal for the first time, the bike is very happy.
    #12
  13. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Ah! Something we didn't even know about! Well done getting it sorted.
    #13
  14. coastranger

    coastranger Been here awhile

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    that is why all the people that sell aftermarket diode boards try to sell other bolts or extra ground wires
    the rubber mount ones were problems on occassion and often get replaced with solids

    so I am glad you found the problem, but I bet OMEGA even says something about mounting

    but I still dont get the issue between mexico and colorado
    #14
  15. Tagman

    Tagman JCunningham San Carlos, Mexico

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    I realize fully that I caused the problem that I found. When I bought this board my son and I rode 2 hrs to Colorado Spgs to buy a new stock diode board for his bike.The dealer did not have one in stock but had this Omega board in a drawer with no package or instructions, $25 My sons bike had rubber mounts so I'm sure thats why this didn't work on his, mine had had solid mounts installed although when fully tightened the allen bolts were apparently 1/8 or so to long and never tightened to the board so my ground was just bouncing around with the board ( three of the 4 mounting holes were fried, and I mean fried. 4th never made contact at all).I am kinda amazed I repaired the board and it works so well now. In hindsight it makes sense now. The 3 major diferences from Mexico to the US was extreme heat/humidity, very bumpy roads in Mexico, and sea level compared to 7500ft alt in Colorado. I'm not sure which was the problem or a combination of all of them but I never had an issue with it in Colorado.
    #15
  16. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    On my Airhead diode boards (stock or aftermarket) I've found that it is a good idea to run a ground wire from the diode board to the alternator case (at a minimum). That ensures good regulation.
    #16