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Yamato 80 break in procedure

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  • Yamato 80 break in procedure

    Recently finished rebuilding a Yamato 80, and was wondering how it should be broke in properly. I'm not sure if the prop has to come off or not, and if it does, I don't know how to get the prop pin out, it just seems hammered in, one side flared out, one side not. Not sure if that's how it's supposed to be, or if someone has taken a hammer to it to no avail. Prop is not stock, it's a two blade stainless with pin hole a little past center towards rear

  • #2
    Originally posted by Steven27jack View Post
    Recently finished rebuilding a Yamato 80, and was wondering how it should be broke in properly. I'm not sure if the prop has to come off or not, and if it does, I don't know how to get the prop pin out, it just seems hammered in, one side flared out, one side not. Not sure if that's how it's supposed to be, or if someone has taken a hammer to it to no avail. Prop is not stock, it's a two blade stainless with pin hole a little past center towards rear
    Take a picture of the the pin from both sides so we can see it…..basically from the opposite side from the ‘flared out’ side, using pin punch and hammer… the pin punch should be slightly smaller in diameter than the pin….gently start tapping the pin to drive it out…. you might want to ‘buck’ the opposite side, especially if the pin is hard to get out…. so as not to damage or bend the prop shaft. If this procedure does not work, you might need to have it ‘drilled’ out which might need a machinist to do it so as not to cause damage to the prop or prop shaft. The diameter of the pin is most likely 3/16”. Where did you get the motor? That person might be able to help you if you know who that is.

    For the break in procedure….. go to yamatoracing.com….. there is an owners manual there.

    Or just call Ric Montoya…. His contact info is there.

    Keep in mind that the motor does not have a water pump…. So if you are going to break it in a tank you will have to have a way to get cooling water water to the motor…. the cooling is done by force feed.

    Whoever you bought the rebuild parts from should be able to help you with both of these procedures.

    Good luck with your project. Let us know how it’s going.
    Last edited by DeanFHobart; 09-08-2021, 08:13 AM.
    sigpic

    Dean F. Hobart

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    • #3
      Tell us what you did on the rebuild? Did you bore out the cylinders, new pistons and rings or just rings, ring end gaps, piston to cylinder wall clearance, replaced rod and/or crank bearings, etc?
      "Keep Move'n" life is catching up!
      No man's life, liberty or property are safe while the legislature is in session.

      Comment


      • #4
        I tore it down to the crank to clean and check clearances, put new crosshatch in cylinders with a deglazer, new rings gapped at .3mm, all new gaskets and seals from Tom (don't remember his last name), torqued everything properly, made sure cylinder to crankcase to exhaust flange were flush before torquing, adjusted points to .35mm and Max advance is set to .2" before tdc. Have to clean carburetor, install fuel tank, remove propeller, flush lower unit with wd-40 and refill with gear lube, and get new spark plugs.
        What direction should the sheer pin be tapped out? Also, I picked up a small c clamp from harbor freight and some cheap drill bits, what's y'all's thoughts on putting a socket or some washers over the side of the pin that should come out, then using the c clamp to press the pin out until flush on prop, then using a drill bit a bit smaller than the pin, cut the smooth end of it off and use it to press the rest of the pin out? What y'all think
        Attached Files

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        • Steven27jack
          Steven27jack commented
          Editing a comment
          I have the manual download, it says it's supposed to have a mikuni carb on it, it has a bing carb. Engine is a '76 I believe, don't know if it came with a bing carb that year or if it's a different carb. I was wrong about one of the jet numbers, one is 55, the other 60. Doesn't match description of jets in manual, same with float, it says set to 1", it's shorter than that I believe.

          I understand what your saying about the exhaust now, pulling the powerhead back off to check it

        • Steven27jack
          Steven27jack commented
          Editing a comment
          I just pulled the powerhead back off, and the internal megaphone is missing. I'm guessing because it was running the header exhaust, the previous owner before me was trying to build it back to stock, but gave up early. He did get the exhaust manifold, which wasn't on the engine when he got it from I don't remember who, it had the header setup, but no pipe. Should I set it up with a tuned pipe? If so, where should I find one? Also had a thought of buying a newer modern 31mm or 32mm mikuni carb that I am more familiar with, and be able to tune easier. I could also run regular pump gas without damage to engine correct?

        • Steven27jack
          Steven27jack commented
          Editing a comment
          I used the clamp method, and with all my might got the pin to move 3/16" one way, saw a gap on the side I pushed out between the pin and prop, so I'm guessing that side is the smaller tapered end, it was flared so I filed the sides of the pin to make it round again. Sprayed pb blaster, again, have been, put the clamp back on it and forced it the other direction, but still just as hard to move...it's not coming easy, next going to lay the lower unit on its side and figure out how to support prop and shaft, and try driving it out with a punch a little smaller than the pin.

      • #5
        I have plans for a fralick hydro I got a few months ago, after I found and picked up this engine off of Facebook marketplace, had been looking at outboard racing hydros fora few years and really dig it, been part of dragboat racing all my life, but, my budget doesn't agree with that pricetag at this moment lol. I also race fast electric radio control hydros, 1/10 scale, and I'm pretty good at it too. I just love hydros in general

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        • #6
          Piston to wall clearance was well within spec, .07366mm top cylinder to piston, .04826mm bottom cylinder to piston

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          • Steven27jack
            Steven27jack commented
            Editing a comment
            I had a machinist buddy of mine measure the cylinders with a telescoping guage and micrometer, and measured pistons with micrometer at x1,x2,x3, y1,y2,y3, got difference between the two then divided by two, which should be piston wall to cylinder wall clearance

          • ZUL8TR
            ZUL8TR commented
            Editing a comment
            So all you did was glaze bust the cylinders with X hatch and the same pistons went into the same cylinder and the clearance is what it was + a smidgeon more due to glaze bust. Did you use a ball hone for the glaze bust?

          • Steven27jack
            Steven27jack commented
            Editing a comment
            No I used a 3 stone glaze buster from orileys

        • #7
          The prop looks to be made for Jim McKean, Not sure what class it was used for. I know his son Sean raced novice way back.

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          • ZUL8TR
            ZUL8TR commented
            Editing a comment
            The other side of the prop has Hopkins is that different than McKean or was it reworked and stamped?

        • #8
          I also have this exhaust header, and the tuned pipe support bracket, but no tuned pipe. The carburetor in the manual says its a mikuni, but the carb on the engine is a bing. Any thoughts if this was setup with a tuned pipe it's last time running?
          Attached Files

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          • #9
            Hopkins made the prop for Jim McKean. He always put the name on the prop who ordered.

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            • #10
              These are two pictures of "complete" I have right now. The cylinder head has "modified .120" stamped on it, I'll be getting a picture of that later, as well as the tag on the lower unit. The intake is drilled for a pulse pump application, the gentleman that I got this engine from said it had no fuel tank, so I'm guessing it was setup with a remote fuel tank and pulse pump. I bought this engine from Facebook marketplace for $800, from an older gentleman that restores antique outboards, but he gave in I believe when he couldn't get the prop off, and sold it, I bought it. Wish I knew who he bought it from...
              Attached Files
              Last edited by Steven27jack; 09-11-2021, 05:15 PM.

              Comment


              • ZUL8TR
                ZUL8TR commented
                Editing a comment
                If you want to pulse pump it with remote tank there is a hook up available at BTM, This will give you more water time with more fuel on board. The gravity tank is about 15 min at full bore, but plan on 10 to get back to the launch.

                https://btmco.com/product/3250-yamat...its-80102-302/

                Have you removed the prop?

                A cold compression test will probably tell what the .120 mod might mean. My cold Y80 with throttle open full pulls 150 psi in 4 rope overs with my gage. I do them cold so temp is a fairly constant value compared to doing it hot. It is only a reference for engine condition so keeping things fairly constant for relative results is important

              • Steven27jack
                Steven27jack commented
                Editing a comment
                Still haven't removed prop, alot of this stuff I have to get help with, or find a way on my own, hence the clamp to try to remove the pin, because I use a wheelchair to get around, and my hands don't work so well, I.e. I can't easily hold onto a hammer and punch at the same time. This entire go-through has been a process for me, but I refuse to give up. When I got engine, rings were stuck, and it only had 60psi and 40psi on cylinders, 40 being top. Ring gaps were .6mm on used rings, still a bit of life was left aye?

                As far as exhaust, I don't believe I can run it without a tuned pipe or internal megaphone correct? Wouldn't doing so result in burning/seizing pistons due to too short of exhaust?

              • Steven27jack
                Steven27jack commented
                Editing a comment
                Success, got the propeller off with help from a friend

            • #11
              Sounds like the original engine was modified for the RB class in PRO outboard division. When the new Quincy engine came out it ruined the class and it was dropped. The engine now could have been used for a C mod engine. Too bad you can't find out who owned it. The McKean's are from Texas.

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              • Steven27jack
                Steven27jack commented
                Editing a comment
                I guess it's time to start Facebook stalking Mr. Jim McKean? Lol, see if I can find him and if it belonged to him

            • #12
              It might run without the stock Megaphone? But power would be down. Try to get the stock Megaphone complete and the 3 tapered seat Philips head bolts. The shims can be easily made from aluminum cans. There are 2 parts: per the parts manual the exhaust megaphone holder #6 and the exhaust megaphone #7. Forget the mod stinger pipe setup and get used to the stock Y80 on the hydro.

              Measure the diameter of that 2 blade, would be nice to know the pitch, great if a pitch gage is available . There are simple methods to get average pitch with basic tools if interested. That just may be a mod prop and a bit too much pitch and diameter for the stock Y80?
              "Keep Move'n" life is catching up!
              No man's life, liberty or property are safe while the legislature is in session.

              Comment


              • Steven27jack
                Steven27jack commented
                Editing a comment
                The diameter is 6 1/2". Have to get protractor to measure pitch

              • ZUL8TR
                ZUL8TR commented
                Editing a comment
                For the stock Y80 that diameter is about right and maybe just a bit too small but pitch will better zero it in as well as other things on the prop like blade shape, cup, rake, blade thinness, etc.

            • #13
              Jim McKean passed away several years ago. His son Sean is on FB.

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              • #14
                Any idea as to what 88 degree stamped on cylinder block would mean, or modified .120 on cylinder head? Would that mean exhaust timing is at 88 degrees, and the head had been shaved .120 to increase compression ratio? The head gasket that came with the engine is thicker than the new head gaskets, any rhyme or reason to that? I'm thinking the thicker head gasket may lower the compression ratio of the shaved head closer to the stock compression ratio, should I go for that or try to keep compression ratio as high as allowed?
                Attached Files

                Comment


                • ZUL8TR
                  ZUL8TR commented
                  Editing a comment
                  Stock port timing on the Y80 is 62 intake and 83 exhaust Degrees BDC measured from bottom dead center from open to close. The exhaust is open a total of 83 x 2 = 166 crank degrees from open to close. The 88 Timing stamp I think references increased exhaust port open to close of 5 x 2 = 10 degrees more crank rotation or total 176 degrees, done by raising the exhaust ports. Done for a mod engine as well as the 0.120 stamp on the head.

                  The stock head gaskets come in 2 thicknesses 0.5 and 1.0 mm and they are aluminum.

                  How thick is the gasket that came with the engine? Is it aluminum?

                  You can do a compression check to see what the engine is making just for reference with that gasket it came with. Will change with break in but at least you know where you are starting at. Lots of oil in the cylinder will boost the test compression. Check after break in. I do cold compression tests to keep temp variable about the same - compression is just a relative measure so always do it the same way and with the same gage. Stock Y80 with 18mm head will pull at 150psi compression. Your mod Y80 will be different.
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