So, can you do it yourself using a dremel. The thing to do is just use the search on porting and you'll find. Just don't file to much, cause you can't go back.
So, did the expansion chamber help your 66? How many miles have you got on engine? Use a NGK B5 plug at about .028 gap with better wire. Also, you might want to use close to max air pressure in tires. (Go semi-slicks) helps!~ I really read everything concerning boost bottle? I've got on slant 48cc Skyhawk also,and I can't decide? It tops a bit over 35. So, still putting on slant 66cc Skyhawk motor out of box. Check out my 48 on pictures Geebt48cc.
Glen PS-Go AMSOIL synthetic after few tanks
Glen