Converting folding 4hp to 6hp

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  • March 14, 2015 at 7:13 pm #921
    johnyrude200
    Participant

      Hi All,

      Recently acquired a 4hp folding. I was wondering if anyone has tried putting a lower unit folding on a 6hp motor (the leg, not the gearcase)? This one has the weedless drive.

      Two questions – can I interchange a standard 4hp folding gearcase with the weedless drive?

      2nd – To do the full conversion, could I switch a 6hp gearcase out with the foldable driveshaft from the 4hp?

      Just figured I’d float this question out there to see if anyone else has tried this one. Would be pretty nifty to have a shifting, foldable 6hp motor as a backup. I know in the late 60’s, the difference between the 3-5hp motors was negligible, and the powerhead was the same for the 4-6hp less the carb.

      March 14, 2015 at 7:28 pm #11962
      mr-asa
      Participant

        Interesting idea.
        What mechanism does the folding unit use to connect the driveshaft? If everything bolted up, i b would think that would be the main weakness.

        March 14, 2015 at 7:36 pm #11964
        johnyrude200
        Participant

          It is a split drive shaft with interlocking articulations; there are two bolts that tighten down (one front, one back) similarly to a wood clamp. I mean, the only thing I’d be scavaging would be the lower unit. Fortunately, I have 3 other regular 4hp motors, so comparing parts might be possible to check for compatibility.

          I’m not even going to bother doing a cross reference of motor compatibility. I know I won’t find any. My main concern is would a folding driveshaft hold up to the torque of a 6hp motor powerhead….and would that driveshaft be compatible with a 6hp gearcase pinion(shifting) & 6hp crank?

          March 14, 2015 at 8:57 pm #11969
          Mumbles
          Participant

            The four and six horse motors are two different animals. The only thing they share is the fuel they drink.

            Mind you, the mid sixties five horse Johnson LD series were a detuned six horse motor sitting on a three/four horse style lower unit.

            March 14, 2015 at 9:05 pm #11971
            oltimer
            Participant
              quote Mumbles:

              The four and six horse motors are two different animals. The only thing they share is the fuel they drink.

              Mind you, the mid sixties five horse Johnson LD series were a detuned six horse motor sitting on a three/four horse style lower unit.

              Plus the shaft size on the 6hp is larger. That would be one large mod to do.

              March 14, 2015 at 9:17 pm #11973
              Mumbles
              Participant

                You got it Jer. Four splines on the six while the others are probably multi splined to.

                March 14, 2015 at 9:34 pm #11974
                frankr
                Participant

                  US Member

                  4 and six have totally different powerhead castings and exhaust housings. So the six isn’t going to fit onto the 4hp exhaust housing. Now if you were to get super creative and make an adapter plate………..?

                  March 14, 2015 at 9:52 pm #11975
                  johnyrude200
                  Participant

                    Those 5hp motors arent too common. I just sold one a week ago, its too bad I dont have another as it would be interesting to see if there was a way to bridge the gap between a folder using a 5hp exhaust/pan, then modifying the pan to accept the tiller and throttle of a 6hp.

                    March 16, 2015 at 11:38 am #12089
                    fleetwin
                    Participant

                      US Member - 2 Years

                      Yeah, don’t think it is possible to make the conversion you are considering.

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