Yes, basecaly it is possible to make engine pretty fast and it will last really short time.
Just take brand new p/l set, washed very well in some sort of thiner to make sure there is no any oil left at all, stick piston to sleeve till it stop and can't move further by pressure of finger, that mesure distance from the top of sleeve to top of piston. On different models it is different numbers, but they are always within 3-4 mm. Then take piston and lap it to size 1.9-1.8 mm, make sure after every laping clean piston with thiner so no any lapping compaund left. Make always sure that before final assembly piston and sleeve must to be washed perfectly. then put motor together and run couple of tanks and motor is ready for it best performance possible, but it will not last really long, but defenetly will work much better then motor run in out of the box. This size works on any 12 size with head button dipness 1mm.
If motor was start ones this technics will not work any more, so P/L set must to be brand new.
Edward