Possible R/R failure and test results

Discussion in '5th Generation 1998-2001' started by Deez, Mar 14, 2021.

  1. Deez

    Deez New Member

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    Hello, I know it's an old topic, but here is the story and what I've found:

    Background: bike is 99 with 13.5k miles. A few days ago it failed to start after practicing a while in the parking lot, water temp was around 220F at that point, pushed it to start and rode home. After arriving, it can start without issue again. I have an OEM replacement that I bought online, which is sold by an individual that claimed it's an old stock that he bought just in case the one on his bike went bad, but he never used it. According the the printed number on the R/R, it's the old model with highest fail rate as the one on my bike. I immediately replaced it with the "new one" without further testing (which is a mistake).

    Yesterday, I rode the bike out, and after around 15 miles, I stopped at traffic light and the rev started to fluctuate, I immediately pulled into a gas station, turned off, and couldn't start again, bike was at normal temp (below 200F). After went through all the trouble and jump started the bike, I was able to ride it back home, but it won't start once arrived.

    Today, I replaced the battery with a new, fully charged one and went through the testing procedure as shown in the service manual and here are the results:
    1. Battery charging at ~13.8V when idling, but dropped to ~13.1V at 5000rpm (under charging).
    2. The battery line and ground line at the R/R connector held same voltage as the battery (the harness behind the R/R seems fine).
    3. Charging coil has consistent resistance ~0.1 cold ~0.5 hot. No continuity between coil and ground (stator seems fine).
    4. Unplugged the R/R, I measured the AC output directly from stator, it was ~20V idle and ~50V at 5000rpm.
    5. The diodes tested fine with the R/R removed from the bike.

    Both R/R performed about the same in the above tests. So the conclusion appears to me is that both regulators are faulty and R/R should be the culprit in my case. What worries me is the chance of both R/R fail at the same point seems pretty low, I wonder:
    1. If there are any other possible causes to my symptom
    2. Which aftermarket R/R would you recommend, I'm currently looking at the Ricks, which costs around $145

    Thanks in advance
     
  2. Deez

    Deez New Member

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    Ps: all connectors are clean and no sign of overheating and burn
     
  3. pi-on

    pi-on New Member

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  4. mello dude

    mello dude Member

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    The Roadstercycle R/R's are the only ones I will recommend.
    As for which one, consider that the SH847 series is larger than stock and will need some creativity to figure out a mount set up in stock location.
    The FH020 is fine (I am running one) a can mount in the stock location by drilling 2 holes.

    Btw - yes both OEM R/R's will leave you stranded.....
     
  5. Deez

    Deez New Member

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    Thanks for your suggestion, I will go with the FH020AA. From the website, it seems not exactly plug and play, did you let the seller know what kind of bike you're putting on and he prepared the connectors for you or did you reuse the stock RRs' connector by cutting and splicing?
     
  6. mello dude

    mello dude Member

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    Using the OEM connectors will get you in trouble.
    Either do a solder with heat shrink covering or a double overlapping crimp butt connector also with marine grade heat shrink tubing. (I have done both)

    Roadstercycle does offer connectors in his kits and is also a ok way to go, I'm OCD and just like to go to overkill on things...

    The bike doesn't matter for any 3 phase charging system....
     
  7. Deez

    Deez New Member

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    Just talked with Jack over email, apparently he works on Sunday night too:)
    Ordered the kit and should be in my mail next week, he told me not to use the stock wiring, looks like the kit has wires that directly connects to the battery terminal.
     
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  8. mello dude

    mello dude Member

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    Right, the harness goes straight to the battery and stator.
    I will post up pics when I can get to my PC.
     
  9. Deez

    Deez New Member

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    Thank you, it really helps!
     
  10. mello dude

    mello dude Member

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    Hi
    Here is the basic wire diagram for the R\R
    [​IMG]

    This is the OEM mount area on the 5th gen..... you will be drilling 2, 1/4 inch holes to mount the new R/R
    [​IMG]

    Here is the R/R install job... -- On the left side of the photo, that is the OEM connector that wont be used, just tape it up good. - On the R/R the bottom 2 wires are going direct to the battery. And the 3 yellow wire go to the stator.
    [​IMG]

    Depending on your mechanicing skill level...... Soldering and marine heat shrink tubing is probably the best way to go to connect to the stator. Alternate 2 is a double overlap butt connection with heat shrink (but you need a pro level type crimp tool) and also the Roadstercycle kit has connectors too.

    Other resources... there are hundreds of charging system threads on here if you search......
    And I may as well throw up #1 -- check post #9
    https://vfrworld.com/threads/how-to-fix-common-regulator-stator-failures.39277/page-7#post-484470


    Cheerz :bruce2:
     
    Last edited: Mar 15, 2021
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  11. Laker

    Laker New Member

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    Mello, you did it again. Very good and thorough instructions. This is what keeps our VFR's running so well. Otherwise its Barbecue Time on the highway. Well done.
     
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  12. Sp00ks

    Sp00ks New Member

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    Just did this to my 98 at Mello's suggestion. Super easy.
     
  13. Deez

    Deez New Member

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    Installed new RR today, the results looked good
     

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  14. mello dude

    mello dude Member

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    14.3 v is perfect.....
    :bruce2:
     
  15. Deez

    Deez New Member

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    Installed a cheap voltmeter today, just in case. The positive side was wired to the fuse box, I noticed the display is about 0.3v lower than the direct reading from the battery terminals. It could be the voltmeter or voltage drop from positive terminal to fuse box.
     

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  16. fink

    fink Member

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    Drop due to resistance in wires and cheap voltmeter. I wouldn't worry about it.
     
  17. mello dude

    mello dude Member

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    Wire direct to the battery with switch and a fuse on the POS side and be done with it.
     
  18. Thorinn Oakunsheyld

    Thorinn Oakunsheyld New Member

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    Hi there; First post. Living in the Okanagan Valley, across the border from Washington's Okanogan Valley. Believe it or not -- rattlesnakes, black widows, scorpions and cacti in Canada. First lengthy ride attempt this week . '85 500 interceptor, trying out new battery and new front tire. About 10 miles from home tach stopped working. 2 miles later bike started to lose power and died. Battery was flat. Charged at home and started right up. Applied "the drill" from the forum and within 5 minutes found alternator connector block loose at r/r harness (yup, 3 yellow wires). Three weeks ago had disconnected connections to access mono shock fittings, and one hadn't locked in. Love those 5 minute/no cost fixes. Will also be installing voltmeter to avoid this happening again. Really enjoy the posts on here.
     
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