Thanks everyone,

It does seem I wiould be better off leaving the engine as it is, and try only to adapt a free flow muffler and a bigger 12.7 mm carb and see if with this tweaks I can get close to 8K RPM´s with a 16x8 prop.

Anyway I´ll try to get my hands on an older engine to tweak it and learn how to port and modify a 2 stroke engine.

Thank you very much.