because it so important to fast people! if I or Skeeter explained the correct way to actually measure compression most people would not have the means or want to spend the time to measure, but lets go through it in simple terms shall we kids, does eveyone out there know what Pi is? no skeeter not the one you eat! notice there is no e on the end! thats used to help us find a measurement, we'll take a 68mm bore that has the exhaust sitting 27mm down from the top of the cylinder. I like to do measurements in inches because I like Skeeter are american, so we have a 68mm or 2.677 bore and a piston travel of 27mm or 1.063 we'll say for this project we'll run a 22cc dome, a std. Yamaha process is to run the piston .010 down from the top of deck but we'll ignore that for this exercise. so
3.1417 (Pi) x2.677 Bx1.063 S = 8.940 converted to cc's because our dome is measured that way is to multiply it by 16.387 to give us a SV of 146.50 cc's being we aren't running a head gasket makes it all the easier and saying were using 22cc domes we are believing that is with the piston not .010 down in the hole and a 9* dome angle, so we take our SV of 146.50 divided by our dome volume 22cc and we get 6.62:1 now remember a few measurements were left out or misplaced strictly for this exercise! but we could just get on the bike and wait until the fat lady is watching and just kick it, next week we'll go over that dreaded squish clearance and why to little or to much is a bad thing...night kids