power I need POWER

Hi Im building a supermoto out of a lifan 150cc dual sport . I want as much power as possible without a turbo or supercharger or no2. I'm lookiing for a big bore kit and a high compression piston. Can i change my 150cc to 250cc with a big bore kit? or only to 200? After that I'm going to have the head ported and polished too and I bought a FmF factory 4.1 titanium slip on paired with a high flow header for a 250r. I'm trying to squeeze every bit of power I can out of it. Do those longer intakes work to make torque ? I cut down a showa cr80r tunable shock that you can adjust for pre load. I gotta get some pics for you guys.