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Race prepping a Yamato ?

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  • Race prepping a Yamato ?

    Say you ordered a Yamato 321 or a 302 and had it delivered to your doorstep. What all would have to be done to it to be ready for the race course ?

  • #2

    Re: Race prepping a Yamato ?

    Say you ordered a Yamato 321 or a 302 and had it delivered to your doorstep. What all would have to be done to it to be ready for the race course ?
    Have the head machined to the minimum spec. I think about .010 is removed. Do not machine the combustion chamber, there needs to be an edge between the flat and the combustion chamber. And have the foot profiled and prop shaft changed to a 9/16. Check the timing and needle valve settings. Then go testing. And of course have fun.
    sigpic

    Dean F. Hobart

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    • #3

      Re: Race prepping a Yamato ?

      If the motor is a 321 to be used in 300SSH,then all you need to do is:
      ​ Add a filter in the fuel line.
      ​ Break in the motor.
      Go racing. If its a 302,then there are a lot of things that are legal to do to the motor,no new 302's are to be sealed.A new 302 will be very hard to find.

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      • #4

        Re: Race prepping a Yamato ?

        I hear people making reference to mag locks and drilling holes for drainage. Someone please explain and should thsee things be done ?

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        • #5

          Re: Race prepping a Yamato ?

          I think what is being referred to is to lock mag from rotation to prevent any movement from the ignition timing it was set at. As for mag drainage if a flip and the engine gets dunked drilled holes in the bottom of the mag allows water to get out otherwise more disassembly required. Should be done for racing these engines.
          "Keep Move'n" life is catching up!
          No man's life, liberty or property are safe while the legislature is in session.

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          • #6

            Re: Race prepping a Yamato ?

            Mike,if you want a new 321,call TJ,he will prepare it ready to break in.If it is to be used in the 300SSH class,no other modifications are necessary.The motor will be run deep enough that cooling should not be a issue.If interested in a 302,then the sky is the limit,lots of used motors out there that have been modified [shaved lower unit,prop shafts changed,14mm heads installed,lower units drilled,blueprinting,etc.]. Which ever motor you want,TJ can get it ready to break-in,no guess work on your part.He may even have some used 302's or may know where to buy one privately.Jerry Davids is also a certified sealer for the 321 motors,and can also prep a motor ready for break-in.

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            • Flatiron
              Flatiron commented
              Editing a comment
              Thanks Joe, still weighing the Pros and cons of which way to go. The Runabout is my Passion and priority so I'm thinking a new/used 321 on it and run CSR and 25SSR and put my 302 on the Hydro and run it in CSH. My MJR is just to nice of a ride to let it set on the trailer. On the other hand 300SSH sure makes things alot simpler

          • #7

            Re: Race prepping a Yamato ?

            Mill head, mill/shape gear box, clean carb, flush gas tank, change prop shaft (if you want a 9/16 shaft) and set timing. Learn about props and boats!

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            • #8

              Re: Race prepping a Yamato ?

              I think I would put your 302 in CSR/25SSR and run a new 321 in 300SSH. Running a 321 in 300SSH will be a lot less expensive because you will not be spending any money on props and engine modifications.Also you have a better chance being competitive in 300SSH compaired to CSH.

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