Home Forum Ask A Member Mercury KD4

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  • #236666
    green-thumbs
    Participant

      US Member - 2 Years

      With reed block/center main bearing assembled to crank shaft and jacks in place time to press assembly inot crank case.
      Check that intake passage and thread hole in reed block will align with
      respective openings in crank case…if not reed block is on upside down
      Fit the assembly into crank case and use 1/16″ drill bit to clock the
      reed block if the drill is 90 drees to face of crank case, thread in reed block and hole in crank case will line up,
      Remove drill bit!
      Press carefully until indicatorn hole in reed block just begins to show
      Then check how thread and hole,
      At this point very slight pressing to arrive at SPOT ON!
      If you get it right the bolt can be screwed into the reed block thread
      without contacting side of hole in crank case.
      A bit of lube on all points of friction and care in aligning with drill bit
      will get it right the first time every time.
      When all is checked and satisfactory remove jacks.

      Sharp eyes will notice this is a KE4 not a KD4…same techniques
      apply for both.
      90 degrees can be eye ball close enough or a simple gauge can be made to clock the reed block.
      I use a 12 ton HF press and some odds and ends made or adapted to
      press crank shafts out or in, for a one off job a couple stron boards and
      a pair of nut washer and threaded rods would work,

      Until I understood the reason for the small hole in reed block I did a lot
      of trial and error installing crank shafts. Sometimes I could get it right
      the first time and at other times 2 or more attempts were needed,
      The hole is present on 1940 K4 and all twin reed block/center main bearing… (1940 twins use external reeds while 1941 and later have
      reeds untegrated into center main bearing.

      • This reply was modified 3 years, 1 month ago by green-thumbs.
      #236676
      Boonie
      Participant

        Canada Member

        Does anyone have torque specs or ring gap info for the KD4 power head? Preferably ring gap and connecting rods.

        #236718
        green-thumbs
        Participant

          US Member - 2 Years

          Rod cap screws 90 INCH pounds
          rule of thumb is 0.004″ per inch of bore diameter
          Opinions will vary,
          Flywheel 40 FOOT pounds
          Reed Valve 30 INCH pounds
          12 INCH pounds equal 1 FOOT pound
          Spark Plug…finger tight plus 1/6 turn to compress NEW gasket.
          Or 15 FOOT pounds
          No specs given for other fasteners which all use lock washers of one type or another.
          Louis

          #236801
          green-thumbs
          Participant

            US Member - 2 Years

            Early K Model twins differ in many details. Tools and technique to tear down and rebuild are much the same 1940 Mercury K4 through 1950sWizard WG4.

            Sharp eyes will notice arm of upper water jacket has been repaired A big Thank You to good guys in chapter, Also of note is use of hex socket head screws to secure water jackets, cyliners to crank case…use what you have to get job done.

            Last photo…primed parts await a warm calm day to paint,

            #237421
            Boonie
            Participant

              Canada Member

              Green thumbs. So on a 2” bore ring gap should be 0.008”?

              #237442
              green-thumbs
              Participant

                US Member - 2 Years

                Go to Otto Gas Engine Works site for an expert’s opinion on piston rings
                and compression.
                Louis

                #237690
                Boonie
                Participant

                  Canada Member

                  What is the preferred tool or procedure you guys use to install pistons and rings. I am having a tough time keeping them ligned up on the little post in the ring grooves

                  #237702
                  dave-bernard
                  Participant

                    US Member

                    piece of soda bottle cut to protect the rings then a hose clamp to compress them. use a lot of lube.

                    #237732
                    green-thumbs
                    Participant

                      US Member - 2 Years

                      It is better to install lower piston first, then the upper piston,
                      Same order for cylinders.
                      There are a few order of assembly details in rebuilding an early
                      K Model that you find out by discovering the way you are trying tod do it is not the way it is done. The frustration involved is not the fault of the
                      machine. Once you wrap your mind around the Kiekhaefer way it begins to make sense. Once you are up the learning curve you may even want to work on another one.

                      Bailey’s, item 10429 piston ring clamp kit, purchased in 2011 for $7.95
                      plus $7.95 S&H The second largest clamp works for 2 inch pistons
                      I have never used the others or found out what the odd parts are for.
                      The bands could be a little wider, but, work ok.

                      Louis

                      #238183
                      Boonie
                      Participant

                        Canada Member

                        What’s the preferred method for installing gaskets on a Kd4 power head. Dry or with some type of sealer?

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