XL185 Resto and Problem

Discussion in 'Thumpers' started by motor_head, Dec 6, 2012.

  1. motor_head

    motor_head n00b

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    I just finished a frame up resto on an '81 XL185. Bought it for $150 running, shifting, and with a clean tank. I did all the work except the frame powdercoating, which a friend of mine did. The engine showed very little wear when I mic'd everything out, so engine part replacement was minimal. Just freshened her up with a hone, rings, lapped valves and all new seals and gaskets. the bike runs like a dream, but I'm having one little problem......She won't charge the battery...... I have checked the alternator and it's ok, so I'm blaming the rectifier. I have done the tests on the 4-wire rectifier and it doesn't pass. So I bought one on Feebay, and it does the same thing. Today I went to a motorcycle salvage yard, found one and tested it with my meter, and it also does the same thing.
    Now I'm beginning to believe the tests in the Clymer manual are bogus. With the positive lead on the red/white wire, I'm supposed to read continuity to all the other three. The green (ground) wire doesn't show continuity on any of the three rectifiers I tested though Clymer says it should. Could all three be bad or is the manual wrong on the readings I should get? The manual also says I should read continuity between the pink and yellow wires and none of the three rectifiers will do that either. I have checked the polarity of the leads both ways to make sure they're oriented right .
    I find it difficult to believe that all three fail the same tests. Anyone else have suggestions/info regarding the rectifier test?

    Here's a few pics of my restoration:

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    #1
  2. kubiak

    kubiak Long timer

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    man that is a great job! i love that year red and black paint colors on the xrs.
    #2
  3. lilsmokey

    lilsmokey Been here awhile

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    Great looking bike! How did you get the chrome sooo damn clean!?
    #3
  4. motor_head

    motor_head n00b

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    Thanks. The rims, spokes and rear shocks cushion assemblies are new. The Shock adjuster collars were re-chromed. As far as the front fork sliders, I used a 3 step process starting with a scotchbrite pad on a die grinder, and ending up with jewelers rouge and a 3/4 HP buffer to put the final touches on them. I re-zinc'd all my own hardware with an Eastwood kit including axle and swingarm bolts, and all the original Honda "8" bolts.
    #4
  5. redprimo

    redprimo Been here awhile

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    Beautiful job, makes the restoration Im doing on my xl500s look look like a hack job.

    I looked in my clymer manual and the test for the regulator/rectifier is done under power. you hoook your meter up to the battery and at 5,000rpm it should read between 8.0-8.9v and as it is reved past that it should not increase. My manual makes no mention of a continuity test. this is for the 6v xl's if you need the numbers for a 12v system let me know.

    did you get a new head tube id plate and swing arm decal from honda?
    #5
  6. motor_head

    motor_head n00b

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    Thanks for the info, I did do a voltage reading at the battery, and under power its down in the 2-3 volt range :(:

    The VIN and data plates were in very nice shape, so the guy who powdercoated the frame used metal ductwork tape to cover them while blasting around them, and then standard type High Temp tape during the powdercoating phase.

    I did get the swingarm decal through Honda.
    #6
  7. redprimo

    redprimo Been here awhile

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    So are all three of your rectifiers testing bad under load? if so that seems odd and I would want to try a known good rectifier just to test the bikes wiring and my meter. Also if so I would refrain from buying any lotto tickets.
    #7
  8. MentalGuru

    MentalGuru Crazy Diamond

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    Sweet!!

    I kept missing the pictures at first.

    :beer
    #8
  9. tundra61

    tundra61 I wish I had a title

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    you got skills man - well done.
    #9
  10. motor_head

    motor_head n00b

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    I haven't tested them all under load, I guess that's tomorrows project....:1drink And definitely no lotto tickets this week!
    #10
  11. motor_head

    motor_head n00b

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    I tested the AC voltage output from the stator on this bike at the rectifier plug. With a light rev off of idle, it read in the 16-17 volt range. Is this adequate to rectify into 7-8 volts DC? The reading on the output side of the rectifier was around 3v DC. If it is producing enough AC voltage, then a good rectifier should solve the problem. If it's not producing enough voltage for the 6v system, I guess a new stator would be in order.
    #11
  12. redprimo

    redprimo Been here awhile

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    Any progress on yur rectifier/regulator issue? also could you post a few pics of your zinc plating set up. I'm kind of regretting not replating some of the hardware on my xl500s rebuild, but my next prject is a 64 honda that I want to do a more correct restoration on and I was wondering exactly how much space a zinc plating set up requires.
    #12
  13. motor_head

    motor_head n00b

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    Red, its incredibly simple. It's around $60 from Eastwood (online). The key is in the prepwork. If you wirebrush and buff BEFORE you plate, the results are much better. Then a light buffing afterwards leaves a nice shiny zinc finish. Its consists of a jar of electrolyte, a zinc bar, and a small D cell battery pack. I'm really happy with the results it produces. It only takes a few minutes of time in the electrolyte to get an adequate coating. It might be easier to send a patch of parts/hardware out for zinc plating, but this is really handy to do it as you need it, one piece at a time.

    As far as the bike, I have another rectifier due to be delivered tomorrow, so I've got my fingers crossed.
    #13
  14. motor_head

    motor_head n00b

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    I finally got back on the charging problem on this bike and discovered that the stator WAS bad after all. I thought it had sufficient output, but when I checked it the second time, it was only putting out 3 to 4 volts. I don't know why I thought I had a higher reading before, maybe the Coors Light. With a replacement stator I'm still only getting 6.5 V DC at the battery at revs, but I know these bikes didn't have much zap anyway. I don't know if this is enough to keep the battery charged, I guess time will tell.
    #14