We planned to enhance the performance of 100cc bike...any suggestions?

Ideas? First idea is no idea what motor you're talking about since you didn't state manufacturer, or model of bike/engine or year. How about it's a 1980 Yamaha 2 stroke dirt bike- you would then usually go to a slightly higher exhaust port by grinding lip 1/2 mm on high side, enlarge carb 2 mm, drilll back of piston at intake side and get reed valve enlarged. Direct fuel injection is also possible if you have money. If the engine is something different -STATE IT. AFTER edit info- Now that we know it's a 4 stroke. First is clean up and exhaust interference at head/exhaust pipe connection- a minor step down of pipe to head port is common- just expand or file pipe so no abrupt change/blockage in pipe connection. Muffler replace with simple cone and spark arrestor screen- you're trying to reduce back pressure by eliminating baffle and using simple expansion chamber and outlet. Old Brooklands silencer still used some. On inlet- carb junction gets abit of match, carb jets need enriched- a slide valve Mikuni may have adjustable needles- raise needle to enrich. aircleaner- low restriction foam instead of tight paper. Cam timing and valve springs- if Yamaha made a racer you might get a reasonable priced cam with quicker lift- don't try higher lift unless clearance to top of piston is there. Fancy fuels or blower - impractical for cost- but if you get some model airplane fuel and use at 50/1 to start you can get a bit more power - be careful , the nitrated fuel causes a bit more heat.