[Mario_Marques]

Wow! nice project dude.
I used to have a pit bike with an engine like that, i had a bore/stroker kit to 140cc, bigger engine head, bigger valves, hi-compression piston, mikuni 26carb, oil cooler, valve breather, and in my final stage i was adding a turbocharger, but i never ended that stage , you can achieve nice performance with that engine tuning the engine and then adding a longer gearbox relation you may build a fast and economical machine.
If you need some advice to tune that engine feel free to contact me.