[QUOTE=Roelof;14945916]With the assembly there is a kind of guideline of how far the piston needs to go into the sleeve until the pinch comes in. If it is in a certain window then it is ok. If not then another piston or sleeve will be tried.

But there is also a perfect height what makes the break-in easy with just taking away the piston its surface roughness with not too much left over pinch or a too low pinch.
If you have several normal engines new out of the box you will notice differences in the pinch, if you have engines with a selection proces from Ielasi, MAX or the early JP then all will have a same height where the pinch comes in.

During the assembly this perfect fit is easy to put aside for the goldhead engines.

I can not say this is really done at OS but several engine brands do select P/S matching sets so there is a highly chance the more expensive goldhead does have selected P/S

impossible your either talking that for the piston to go up to a certain height and stop so either the piston diameter is too small or too big or its the sleeve pinch causing the piston roelof there is no way from piston to piston of sleeve to sleeve there can be such a measurable difference just cant happen, then what if u say is true think of all the other things that could be wrong such as where the bearings sit the opening could be bigger and the bearing would fit looser or tighter on different blocks, carb openings would be different motor to motor cause if what u say is true then it don't just apply to piston and sleeves every aspect of the motor would be different that is impossible!! no way....
also there is no way they set aside the better ones for the gold head for what reason the gold head is not sold as a better motor or sold as a modified motor it just don't add up.
bottom line some motors are just cut sharper like I said and certain ones get the luck of having the sharper pieces put toghter...