Not too sure about your fuel filter but I would certainly try for a tighter squish. 1mm is too much. .68 to .7 is better. This is, of course, is assuming that your big and small ends and rods are in good nick.

It never ceases to amaze me how you can go from a 3.5cc motor through 100cc and upwards and the squish remains VERY similar on all motors. Two strokes of course.

Mike