i got my 80/66cc kit took it out the box i am an engineer took all the burrs off ports did not enlarge or polish changed all the chinese plastic bolts for stainless steel cap heads flatted all mating faces and took 0.6 mm off cylinder head to increase compression slightly put in a decent spark plug mounted into and i think this is the difference a hybrid 700c wheel bike with road tyres and had my mate on his motorbike speed clock me 33mph all stamdard changed rear sprocket 32 tooth and altered needle height for leaner mix not much torque but its flat where i am and now get 38.12 mph and that was taken with a police hand held radar i know him wasnt done so why all the fecking around lol on anything this low powered your greatest by far route is to decrease your rolling resistance before you even cosider spending hours and hours to gain 0.0025 hp get goot hubs large wheels thinner tyres