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1924 Big X

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  • #16
    Thanks JoJo, for the comment and flipping the pictures!

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    • #17
      Fabulous Gene!
      Robbie
      Robbie Knight Amca #2736

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      • #18
        I love these stories. Thank you for sharing.

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        • #19
          Progress on the 24 big X: . Life has thrown a lot of road blocks my way which has slowed my progress to a crawl but still inching forward....

          New connecting rods and engine pins FINALLY arrived a few months ago so I was able to get the crank built and balanced. Rods and pins.jpg

          In the end, I had to remove almost 300 grams total from the crank pin side to achieve static balance of the crank assembly with 1 piston attached. I use a passing wheel stand I inherited from Bill Bradley in Arizona. Not quite as accurate as a set of parallels but close enough for this pony! Rather than drill enough holes to turn the wheels into swiss cheese I opted to mill out material from the inside edge of the flywheel rim. I have a few sets of X wheels, half are solid rim all around and half are milled away on the inside edge of the rim. This begs the question of what the hell did Schwinn do for balancing????? An earlier post I made was to my efforts to reverse calculate the balance factor of a stock X bottom end. I concluded that using the solid wheels and all stock piston, rings and rods, the X crank had a balance factor of about 24% which is nuts! All I can figure is that since the wheels are so large in diameter (won't fit in a HD or Indian truing stand) and all X's were geared very high for the day, they planned on the engine turning quite slow. Interesting to note, it appears the wheels from X that had a relieved section at the pin area were earlier 3 speed models and the later models (late teens and up) were solid. The relieved wheels are close to balanced with 1 piston, however the solid wheels are balanced with NO piston attached! So, after static balancing I disassembled the crank and reverse calculated the balance using the S&S method. I came up with a 61.4% balance factor, which I can live with.
          Flywheels.jpgMore cylinder repairs have been under way too. I picked up a very nice rear on ebay and decided to attempt to resurrect another front that I considered too far gone. The major problem was that my sanblasters decided to just strip the cylinders I brought in rather than take the time to blast them. Problem is they left them in the strip tank too long and the fine threads in the cast iron were partially eaten away, UGH!!!! Made junk out of 4 cylinders! Jim Wall helped with soome fin repairs and truing up the base flange, perpendicular to the bore.

          Truing base flange.jpg
          Next I made some hand dies of sorts and started chasing the threads on the intake and exhaust manifold nipples. I was able to catch the threads and cut a new deeper thread. They are not perfect but good enough to hold a new undersize nut. Also made a tap to clean up the 24 tpi thread in the intake cage hole and redefine that thread as well. Then I made an oversize nut to hold the cage in place. The bore is decent so as soon as set #3 returns from NikaSil bore coating, this set will go out for the same. In the end, I'll have 3 sets of Series 20 X cylinders all repaired and fitted with new valves, guides, springs, and pistons. Overall conditions vary, but will all be usable.

          Cylinder set with new nuts.jpg
          I've discovered a great piston option for any 61" X. A UL piston, +.020" will fit a standard X bore that has been honed out +.007". This will give the same compression ratio of 4.5/1. The wrist pin is considerably larger but the X bushing can easily be reworked to fit. I've decided to go with EL pistons, same bore size as UL but will raise compression to 5.45/1. The beauty here is these pistons are available in many sizes and are easy to source, so no custom pistons!


          Finishing up a few details on the cases before buttoning up the bottom end. I did a dry assembly of the entire engine with no rings or valve springs. The crank turns over easily with no bind or drag anywhere, so it looks like my efforts at squaring things up and setting clearances has paid off!
          Ready to assemble once the engine is buttoned up and cases painted!
          Attached Files

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          • #20
            I really appreciate the information on your piston research, and compression information, Gene. Fitting new pistons to 100 year old blind bore cylinders is a mysterious challenge. That is one of the benefits of the Cannionball, and seeing how motor builders get around the problems replacing dead parts, and making an old engine usable. . . . Just a suggestion; you need to fill those rust pits in your flywheels. Try Bondo
            Eric Smith
            AMCA #886

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            • #21
              Thanks for noticing Eric! I prefer JB weld for filling pits on critical parts. Not that I would do it on the flywheels, but I have used it on the sealing flange of the cast iron intake ports, some of which were severely pitted!! Also used a lot of it to fill nasty pits in the aluminum case and timing cover.

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              • #22
                I was just messing with you about the Bondo, Gene. I think JB Weld, and Devcon are fantastic 2 part fillers and under the right conditions are incredibly durable.
                Eric Smith
                AMCA #886

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