i have now had 3 motorized bicycle kits the last on lasted maybe 2 days and i fried the engine now i have a whack of spare parts so i was considering buying an engine only and adding some upgardes to handle me riding it and also trying differen manufacturer...but im sooo scared too spend the money again i recently got one of those electric scooters .....but that thing is compltely gutless.... the engine was a 66/80 cc 2 stroke (flying engines) what maybe a 4 stroke benefit ? thx