Home Forums 2-Cycle Racing Building jr 3 hole can motor

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    • #77178
      John Tapler

      Any help or info as I am starting to build a junior three hole can motor with big carb  for my son he will run at 285 pounds I was wondering what port height should be high or low. Should I machine the piston skirt to min value or don’t cut to creat faster closing time. Any help would be great. Should I play with timing.

    • #77201
      Morgan Schuler

      The average Yamaha racer isn’t performing their own machine work and an established engine builder might not share that information. Maybe try searching on eknclassic.com in the old forums? You might have to test and experiment for yourself…

    • #77323
      Walt Gifford

      Exhaust can be .030″ lower than legal, cut the skirt for max intake and set the head clearance for .025″ with 15 degree angle and a 1/64″ radius. Advance the ignition to max legal.


      FAA certified jet engine and aircraft technician,
      Nicholson Speedway class champion 2001,
      Yamaha KT100 Service Center,
      41 years karting experience

    • #80608
      Jim Silverheels

      Giff, did you find lowering the cylinder .030 below legal to be more beneficial because the cans rev lower? thanks

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