1938 Handitwin 4261 carb question

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  • January 30, 2021 at 5:41 pm #229102
    DAN UMBARGER
    Participant

      US Member

      Got the magneto repaired…have spark and am trying to get the motor running. Have removed and cleaned the carb and it will start and run for about 10 seconds then die. Will only start the the timer at about 5 o’clock and the needle at 1 to 1 1/4 out. Is there a website or link someone can point me to that explains how these carbs work? If I can see how it’s supposed to work I may be able to figure out what’s wrong….I think it’s running too rich. Have a lot of oil running down the exhaust tube. I am running the oil real rich at the moment…a heavy 16:1 with tcw3. After I shut the fuel off it started running much better until it ran out of fuel. When I had the carb apart the only thing I saw was the valve bumper is deteriorated away…it’s made out of cork I think. Thanks….Dan

      • This topic was modified 3 years, 11 months ago by DAN UMBARGER.
      • This topic was modified 3 years, 11 months ago by DAN UMBARGER.
      January 31, 2021 at 9:17 am #229156
      Tubs
      Participant

        .

        A "Boat House Repair" is one that done without having tools or the skills to do it properly.

        January 31, 2021 at 9:27 am #229157
        Tubs
        Participant

          .

          A "Boat House Repair" is one that done without having tools or the skills to do it properly.

          • This reply was modified 3 years, 11 months ago by Tubs.
          • This reply was modified 3 years, 11 months ago by Tubs.
          • This reply was modified 3 years, 11 months ago by Tubs.
          • This reply was modified 3 years, 11 months ago by Tubs.
          January 31, 2021 at 11:30 am #229165
          DAN UMBARGER
          Participant

            US Member

            Thanks Tubs, That’s exactly what I was looking for. I figured that the bumper was supposed to be bigger than it is. Should it be sealed after installation?

            January 31, 2021 at 3:25 pm #229193
            Tubs
            Participant

              .

              A "Boat House Repair" is one that done without having tools or the skills to do it properly.

              • This reply was modified 3 years, 11 months ago by Tubs.
              • This reply was modified 3 years, 11 months ago by Tubs.
              • This reply was modified 3 years, 11 months ago by Tubs.
              • This reply was modified 3 years, 11 months ago by Tubs.
              1 user thanked author for this post.
              DAN UMBARGER
              February 2, 2021 at 8:27 pm #229339
              DAN UMBARGER
              Participant

                US Member

                A little update on my 1938 Handitwin. First off…thanks Tubs, your were right about the valve bumper…went to Ace Hardware and purchased some cork stoppers, fit one to the valve top cover and filed to the correct spacing. Motor still started and stopped so I removed the rear exhaust housing to check for carbon…found none. The pistons looked fine and the rings were loose. Put it back in the test tank without the exhaust tube and it did the same thing. Soldered in a new condenser I got from a buddy…same thing. Finally ran the adjustment needle all the way in and backed off 1/4 turn and it started right up and ran great. So A note to anyone else trying to figure out where to start the needle…..1/4 TURN OUT!!!! Doesn’t like to idle well yet but I have a temporary fuel system hooked up to run it while I’m in the middle of removing the rust from the fuel tank….while it starts with one pull I have to lean and richen it at different rpm’s. Cool little motor. Will get it running better before I consider cosmetically restoring it.

                December 29, 2024 at 6:28 pm #292960
                T….in Wisconsin
                Participant

                  US Member

                  Hello Dan,

                  My 36 Handitwin has the same symptom with fuel running down the exhaust tube. Mine is also good for about 15-20 seconds before stopping and runs better after closing the petcock a running the fuel out. I had very similar  scenario on A-45. Remedy on the A-45 was to set the needle valve to 3/4 turns out from soft stop.

                  In both instances the objective is to throttle back the fuel supply.

                  Point of interest:

                  On the Handitwins the “1/4 set point ” would need to be set with the lean/rich adjustment lever positioned to the far left. If the 1/4 set point is set with the lever to the far right the needle valve would reach the soft dead stop about mid position on lever travel to the left.

                  I guess a better way to put this is to back the needle valve off 1/4 turn from soft dead stop and then oriented the lever to the far left travel position, slide over stem and lighten.

                  Am I on the same page?

                  T….in Wisconsin

                   

                   

                   

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