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Thread: Air cooled 2-cycle motorcycle racing cylinder

  1. #131
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    A quick update: as of today Jeff is leading 200GP nationwide with 7147 vs 6775 points (2nd place) and 250GP with 7590 vs 4000 points (for 2nd place).

    cheers,
    Michael

  2. #132
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    Wow!
    Veni, vidi, vici !
    This has been an amazing thread.
    Go Jeff !!!!

    Any more links to vids?
    Bones

  3. #133
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    Jeff is getting ready to pour another batch of medallions in a couple weeks for his yearly off-road ride (which may be taking place this weekend) so I don't think he's got any other foundry activity to report. He's trying to hit all but one of the races around the country so traveling, preparing, and catching up after the races is taken up his time. The new medallion is another 3D print.

  4. #134
    Senior Member 4cylndrfury's Avatar
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    Hopefully he is photo documenting his escapades, and has intentions to provide a full report on his casting adventures/racing campaigns!

  5. #135
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    The last two rounds of racing at GingerMan raceway in MI, and the big track Road America in WI were a success! I am proud to announce that I am the Current points leader in AHRMA GP200 and GP250 class! There are 8 races to go in the series (4 individual meets) I will be able to make 3 of them: Miller Motorsports in Utah, little Talladega in Alabama, and Barber in Alabama. They count your 10 best finishes for the National Championship, so my score can only get better as I have already ran 10 races in each class. However there is tough competition and teh championship is still up fro grabs!



    AT GingerMan and Road America I ran the two iron lined cylinders on page 13 of this post.
    The first iron lined cylinder has now seen close to 450 racing miles at 8000-10000 RPM and is still in good shape, I just lightly honed and changed piston rings after 300 miles. I had to pull that engine though after the last race at GingerMan due to a problem with the crank shaft causing a nasty vibration. Gingerman is a short tight (curvy) track and forces a lot of harder downshifts and high RPM. My transmission has two wide a ratio between 3rdand 4th gear and the track seemed to want that transition in many of the corners. I think it was those punishing downshifts that eventually damaged the crankshaft. At GingerMan I finished 4th and 3rd in the two GP200 races and 4th and 2nd in the two GP250 races.


    Here you can see a real dog fight for 4th in GP200, they gridded our class as the third wave behind two other classes: Novice production light weight, and Class C hand / Class C foot shift. That was a total of 25 bikes that started in front of my class GP200! So not only did I have to battle the top 4 GP200 riders for the podium we actually overtook all 25 bikes in the first two waves by the end of the race!!!


    Here is a healthy piston crown after 300 racing miles at 380-405 oF CHT. still cross hatch on the cylinder too!



    So I ran at Road America with my second engine that had a brand new piston and the second “brand new” iron lined cylinder. Road America is a long track a little over 4 miles per lap. This is twice as long as every other track we run. The long straights at Road America put a lot of strain on the little motor, due to just so much time spent at wide open throttle and peak RPM. Between Friday practice and racing two classes on Saturday and Sunday I put close to 300 miles on the new motor! Battling the heat in the engine on the big track was a challenge I had to jet a little richer and retard the timing to keep it in check. Even with the down tuning I had to push it hard enough to keep up with the fastest bikes on the grid that my cylinder head temp was reaching 420 oF and spending a lot of time over 400 oF. That is the danger zone, I just had to hold the throttle and pray it didn’t seize, or back off and loose. I prayed and didn’t let up and finished 3rd and 2nd in the GP200 races, and 2nd and 2nd in GP250. In the second GP250 race (the last race of the weekend) I did finally seize a piston, but by random luck enough bikes had dropped out that I finished 2nd! I have never seen 8 bikes pull out or not make it to the grid! That just doesn’t happen, so that was dumb luck, but I will take it! The seize turned out to be a mild hot seize and when it cooled down it was free again.



    Jeff is getting ready to pour another batch of medallions in a couple weeks for his yearly off-road ride (which may be taking place this weekend) so I don't think he's got any other foundry activity to report. He's trying to hit all but one of the races around the country so traveling, preparing, and catching up after the races is taken up his time. The new medallion is another 3D print.
    -Yep Michael, I will start the pattern making for the trophy medallions tonight, and hope to pour this Sunday, I will take lots of pictures, and post a separate pattern making thread about those on Alloy Avenue.

  6. #136
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    Woo Hoo! Thanks for posting your racing videos, Jeff. Here in Austria, we don't keep the fingers crossed, but "Drucke die Daumen" - Press the thumbs for your success.

    How long does it take you to drive from San Francisco to Alabama? You must have spend a lot of hours on the road this year, the way those races are spread over the whole country.
    Mark

  7. #137
    Senior Member 4cylndrfury's Avatar
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    Man, the success youre having with these cylinders is incredible. It really gives me a deep appreciation for the prep you did, the execution of your design, the quality of your casting and final machining. Youre living my dream...design, cast, and build a competitive vehicle, and then compete with it. A championship trophy would put the icing on the cake. Great work!

    Looking forward to watching the medallion thread as well!

  8. #138
    Amazing! Best of luck from the Alloy Ave fan club!

  9. #139
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    I imagine nobody in the paddock believes you actually cast this stuff.

    Great results and what an achievment! Keep the fan club posted!

  10. #140
    This post prompted me to join this forum so my first post is a big "thumbs up" for an excellent writeup.

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