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Dads Sport Scout

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  • #61
    You are doing a fantastic job of documenting your progress. I can read text, but I'm a picture oriented guy. Thanks for what you are doing, and sharing.
    Eric Smith
    AMCA #886


    • #62
      Nothing too thrilling here, getting ready to button up the bottom end but want to check that the mounting plates fit all nicey nice. That includes the hex rods that carry the floorboard mounts. Here is the front hex rod as it came off the bike with the brake pedal and assorted spacers.

      Some cleaning and further inspection showed the hex was a bit banged up and bent. Rather then f around with it I looked for and found a replacement in my stuff, the 1940 and up Scouts had the brake pedal pivot right on them, different then the earlier Scouts that had a cast pedal mount that fit on the hex section. Anyway, here's the one I decided to use.


      Saves me some time. It slid right in thru the engine mounts so we good to go.


      The back engine mounts are new and special for the Big Base cases, but they didn't have the spacer installed on the left hand side for when the front frame section is mounted. As luck would have it I found one of those spacers so I got to install it and give the engine mounts a coat of paint. I have found that Rustoleum high heat silver is a nice matte silver color close to cadmium, so that's what I'll use.

      To be continued.


      • #63
        I'm enjoying all of the special big base details that you don't find on a stock sport scout. However, I'm puzzled - big base motors were designed to run with a magneto, yet yours has a distributer. How was your electrical system powered without a generator? Was it run total loss?
        A. Bernhardt
        AMCA# 9726


        • #64
          Hey Mr Bernhardt,

          I don’t know the reason for no magneto, my father bought it late 60’s so who knows what they did to it the preceding 20 plus years. It is total loss. At some later date I’d like to convert it to magneto, but for now it’s going back together like my father rode it. He said it was a fast bike, but you couldn’t go too far cause of the total loss.


          I run total loss on one of my Scouts and it works fine. I ran it for 2 days at the Race of Gentlemen without recharging the battery.


          • #65

            I haven't posted in a while, was busy last week getting ready for, going to and recovering from the Oley meet. And then I couldn't post pictures for some reason but that seems to work now. Anyway, I had to make a few modifications to the engine mounting plates. The bike had standard Sport Scout mounting plates, but the bottom rear mounting hole on the cases is in a different position because of the oil sump, the previous builder just bent the plates in that location for clearance and left that bolt out (?!). The new plates fit correctly, but are missing a few things.


            The right hand plate has a 1/4-28 threaded hole near the top that the top chain guard screw mates with, this had to be added as seen in the before and after pictures above.


            Something I didn't anticipate is shown on the left hand picture above. The first two holes on the bottom of the standard plate are for mounting the bottom of the rear frame section, the rightmost hole is a bolt thru the engine case, and the fourth hole is for mounting the header pipe support as shown. But the new plate only has three holes, but fortunately the case bolt hole seems to line up with the header pipe support hole (see last two pictures) so I should be good, I'll just have to use a longer bolt. Whew, that was close.


            • #66
              The left side mounting plate should have a spacer pressed in so when the front frame section is attached the thru bolt doesn't crush the plates in. This was missing from the new plate, but I luckily happened to have a spare spacer. Took it to my friend Pete to weld it and we are good to go.


              One final test fitting then a coat of paint. Making progress.


              • #67
                Not much to this post, cleaning up the pistons so I figured I’d get some before and after pictures.


                That’s it for today, weekend coming up hope to get a lot more done.


                • #68
                  You have got me hooked can't wait to see when it's done!


                  • #69
                    Well, the first piston went smoothly, so the second one in theory should too, right?


                    Gee, there is a lot more corrosion on this one, and the top compression ring and the oil ring are not moving in their grooves, hmmm, ok, clean with some lacquer thinner, some PB Blaster, some heat, rinse and repeat many times, let it soak in thinners overnight, some more heat and what do you know they are moving a bit, some more heat and juice and it looks good and then


                    Fffffffffudge......(actually another on syllable word that starts with fu).....
                    oh well, guess I need new rings. I have some Scout rings, maybe I’ll luck out. No, I won’t.


                    • #70
                      OK. So now I need some rings. The pistons in the engine are .040 over, says right on them....


                      Yep, .040 plain as day. But not all is as it seems. Good thing I decided to check.


                      I happen to have some .010 .020 and .030 Scout pistons so I decided to measure the stroker pistons. The standard bore for Sport Scout is 2 7/8 or 2.875". According to the overhaul manual I have the standard piston clearance is .003", so the standard piston should be 2.872". I measure the .010 over piston and should get 2.882", I get 2.880, close enough.


                      I measure the .020 over piston, should be 2.892, I get 2.891.


                      I measure the .030 over piston (no pictures), should be 2.902, I got 2.900. Now the moment of truth, I measure the stroker piston and get...


                      2.890"...??!!?? these are .020 over, not the .040 that are literally stamped on pays to check I'll tell ya.


                      • #71
                        A little further checking going on now, want to see the fit in the cylinder.


                        Yep, my .020 over piston feels pretty good in there. The manual says.


                        For the 640B (Military model Sports Scout) there should be .003 clearance measured as shown above. Checking it out


                        Both my .020 over piston and the stroker piston have about .006 clearance.....hmmm.....the manual says .006 clearance for the 741 (30.50" 500cc military model)...Did the builder loosen up the clearance cause it was a stroker, I have no idea. But I'm going to go with it. This was a running bike, I'm not going to get the cylinders bored and go up a size, it'll be fine the way it is. I'm not riding to California on it after all. Just glad I checked and didn't waste time and money on .040 over rings. A set of .020 over rings and I'm good to go...right? Not so fast....another problem about to rear its ugly head...


                        • #72
                          Maybe they are .040 over on a different bike? Good catch though
                          AMCA #41287
                          1998 Dyna Convertible - 100% Original
                          1982 FXR - starting restoration
                          1979 FXS 1200 (1340) nearly done
                          96" Evo Softail self built chopper
                          2012 103" Road King "per diem"
                          plus 13 other bikes over the years...