DAVE ASKED ME TO EDIT OUT THE AUTOMOTIVE INFO SO HERE IT IS EDITED
I DONT THINK THE PISTON KNOWS IF ITS 2CYC OR 4CYC WHEN IT COMES TO HEAT EXPANSION.THIS IS A PROVEN 4CYC RACING PISTON DESIGN
SKIRT LENGTH IS 65% OF THE DIA. SO A 1.0 DIA. PISTON SHOULD ONLY BE .650 LONG
NO SKIRT BELOW THE WRISTPIN
PISTONHEAD DIA IS .005 UNDER BORE DIA
SKIRT DIA IS .0018 UNDER BORE DIA
RING END GAP .004 2ND RING & .005 TOP RING
IF YOU CAN PICTURE THAT PISTON IN YOUR MIND ITS ONLY 1/3 THE MASS WE HAVE IN THESE 25CC ENGINES. CAN ONE OF YOU 2CYC EXPERTS EXPLAIN THIS TO ME? SOMEONE TLAKED ABOUT LAPPING THE PISTON. DO YOU LAP IT IN THE BORE WITH AN ABBRASSIVE COMPOUND AND JUST MAKE IT SMALLER LIKE PUTTING IT IN A LATHE AND TURNING ITS DIA DOWN? WE CANT DO ANYTHING ABOUT THE HEATED INCOMING AIR REDUCING THE VOLUMETRIC EFFICIENCY BUT MAYBE THE SHAPE NEEDS WORK.