[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.

[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…

[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.

Gif

[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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