Picked up a Honda TRX400 quad with a GS500 motor

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  • tywhitty
    • Jan 2026

    #1

    Picked up a Honda TRX400 quad with a GS500 motor

    So i picked up a Honda TRX400 quad that someone had stuffed a Suzuki GS500 motor in. All of the electrical is from the donor GS. First of all, i am trying to figure out the year of the engine. The engine number is M504-113807. Is there a way to figure out the year of the engine from this number? The wiring is a rat nest and i would like to make sure im looking at the right diagram before i attempt to get this thing running. Thanks for any advise .
  • tom203
    Forum Guru
    Past Site Supporter
    • Aug 2010
    • 8925
    • Norway,Maine

    #2
    Since this thing has the suzuki electrics, look for the ignitor box- the part number might give you clues to the year.
    And don't forget to post pics- this place likes disasters
    1981 gs650L

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

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    • tywhitty

      #3
      Ok thanks, i will check out the ignitor and take a few pics when i get home

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      • tywhitty

        #4
        Heres a couple pics
        Attached Files

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        • tywhitty

          #5
          A couple more pics
          Attached Files

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          • tom203
            Forum Guru
            Past Site Supporter
            • Aug 2010
            • 8925
            • Norway,Maine

            #6
            The ignitor is a about the size of a cigarette pack- unlikely to have heatsink ribs like the regulator/rectifier.
            1981 gs650L

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

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            • TxGSrider
              Forum Sage
              Past Site Supporter
              • Aug 2015
              • 1015
              • Flower Mound, TX

              #7
              It seems to fit pretty good. lol
              I've messed with quads for several years now, and its kinda funny to me that you can mod the heck out of a 450cc sport quad to the point where its not really fun to ride (and spend thousands in cams/head/exhaust) and get maybe 60-70hp, or you can find a pretty "mild" street bike motor (2 or 4 cylinder) around the same displacement that starts with nearly that kind of power (and goes way up if you get a late model sport bike motor). In fact Ive seen R6 and R1 motors from totaled street bikes put into $100 quads and are so ridiculously fast that its scary... and still have less than $1500 in the projects.
              Good luck with that and have fun on it.. it looks like a great toy.
              1982 GS1100E "Jolene"

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              • tywhitty

                #8
                Heres my ignitor... not sure how to decipher the numbers yet
                Attached Files

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                • tom203
                  Forum Guru
                  Past Site Supporter
                  • Aug 2010
                  • 8925
                  • Norway,Maine

                  #9
                  Originally posted by tywhitty
                  Heres my ignitor... not sure how to decipher the numbers yet
                  Me neither, most suzuki ignitors are like 32900-xxxxx on the gs500 model. Check your signal generator setup to make sure it appears stock ( remove little cover lower right side)
                  1981 gs650L

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

                  Comment

                  • tywhitty

                    #10
                    Using the color diagram for a 81 gs550 for reference, i patched up some of the rat nest this morning and managed to get this thing to fire up. Seems to run pretty good- has a little hesitation when revving from idle, but i think i can cure that with a little carb clean and dialing in. I havent got to ride it yet, it doesnt have a chain... but im planning on grabbing one tonite.

                    Comment

                    • hillsy
                      Forum Sage
                      • May 2008
                      • 1469
                      • Brisbane, Queensland, Australia

                      #11
                      Keep us updated - this thing looks like it could be a ton of fun
                      Current:
                      Z1300A5 Locomotive (swapped my Intruder for it), GS450 Cafe Project (might never finish it....), XT500 Commuter (I know - it's a Yamaha :eek:)

                      Past:
                      VL1500 Intruder (swapped for Z1300), ZX9R Streetfighter (lets face it - too fast....), 1984 GSX750EF, 1984 GSX1100EF (AKA GS1150)
                      And a bunch of other crap Yamahas....

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