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Old 10-12-2012, 07:39 PM   #15
bmwrench
Beastly Adventurer
 
Joined: Nov 2006
Oddometer: 1,898
The R75-R90 heads have a flat band around the outside of the chamber and a matching one in the piston. The piston comes closer to this band than the hemispherical part of the chamber. This close clearance causes turbulence in the chamber, mixing the fuel and air better than if there were none. I don't know when or who first called it a squish band-I suspect the British-but it has been called that as long as I can remember.
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