Hi!! New in the community, I have just finished my motorized bicycle !!!! The time to construct this was 4 days, and the result is EXELLENT!!!! There is a 35cc 2-stroke motor (from a kraut grass trimmer) with 78mm auto-clutch (modified) bringing out 1.2 bhp. you may not be satisfied how fast it goes from the videos, but bear in mind that my fat body has a 110 kg weight.... I am sure that if i was 20 to 30kg less it would go a lot faster!!!! It's speed (with me on board,) is adout 45 km/h downhill (max) and uphill, 20 km/h (max). I am so satisfied from this project, because the motor is used for about 2 years, and the whole project costed me about 100 euro (about 80 u.s. dollars) Here are some pictures, and videos from youtube. Feel free to make comments good, and bad.