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    Fh020aa

    I'm curious if the FH020AA R/R is as good as the SH775AA ? What is the difference between these two ? Is one, as good as the other, for our bikes ?

    Thanks.
    Larry D
    1980 GS450S
    1981 GS450S
    2003 Heritage Softtail

    #2
    Originally posted by Larry D View Post
    I'm curious if the FH020AA R/R is as good as the SH775AA ? What is the difference between these two ? Is one, as good as the other, for our bikes ?

    Thanks.
    You want the series SH-775....it's much easier on the stator
    1981 gs650L

    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

    Comment


      #3
      Not doubting you , but,.....easier, in what way ? Obviously, my R/R is out on the 450S. I've been doing a bit of reading and it seems both of these R/Rs have been highly recommended by folks on the interwebs.
      Just wondering what makes one better than the other.
      Larry D
      1980 GS450S
      1981 GS450S
      2003 Heritage Softtail

      Comment


        #4
        Originally posted by Larry D View Post
        Not doubting you , but,.....easier, in what way ? Obviously, my R/R is out on the 450S. I've been doing a bit of reading and it seems both of these R/Rs have been highly recommended by folks on the interwebs.
        Just wondering what makes one better than the other.
        The FH020AA is a mosfet (shunt) type R/R that puts stress on the stator, the SH775 is a series R/R and does not. As I understand it, when there is no demand on the battery, the voltage is shunted directly to the ground on the shunt type R/R. In the Series style, the voltage regulator turns the charging system off. Therefore reducing stator current and thus heat build up.

        EDIT: I am not 100% sure on the accuracy of the underlined, so someone more knowledgeable may come along and correct me, but to my understanding that is the difference
        1982 GS850GL - Shaved seat foam and new seat cover; Daytona handlebars and Tusk risers; Puig "Naked" Windscreen\
        1978 KZ200 - Mostly original, hydraulic front brake swap, superbike bars; purchased at 7k original miles
        Track bike project: 2008 Hyosung frame w/ 97 gs500E engine swap (in progress)

        Comment


          #5
          Gotcha. I was thinking that they were both series type R/Rs.
          Larry D
          1980 GS450S
          1981 GS450S
          2003 Heritage Softtail

          Comment


            #6
            Shindengen's documentation is a bit convoluted and hard to find, but yes, the SH775 regulates by disconnecting the generator, whereas the FH020AA shunts.

            Not sure if the monikers 'series' and 'shunt' are the correct english technical terms.
            #1: 1979 GS 550 EC "Red" – Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
            #2: 1978 GS 550 EC "Blue" – Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
            #3: 2014 Moto Guzzi V7 II Racer – One needs a runner while wrenching
            #4: 1980 Moto Guzzi V65C – Something to chill

            Comment


              #7
              Yes, those are the correct, or at least common, terms.

              Larry, to put it in another light, a shunt-type regulator, whether stock or aftermarket, like the FH020 or the FH012, regulates by diverting the output. Some say it goes straight to ground, others will say it goes back through the stator, but either way, the stator is putting out as much as it can, all the time. What the bike 'sees' is a bit less because it is interrupted quite often, so the average output is proper.

              A series-type regulator, like the SH775 or a Compufire, will also regulate by interrupting the output, but it does it by simply opening the circuit, not diverting the output. That reduces the average current through the stator to something less than full output all the time. That is what reduces the load on the stator, helping to keep it cooler.

              Be careful shopping, though, there are a LOT of regulators that look like an SH775, but are not series-type regulators.

              .
              sigpic
              mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
              hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
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              Comment


                #8
                I am happy to report that after installing a new Caltric stator and a SH 775 R/R, the '81 GS450S is charging at a solid 14.8 volts at 4000rpm and at about 14.1 at idle.
                Larry D
                1980 GS450S
                1981 GS450S
                2003 Heritage Softtail

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