I am thinking of buying a KTM 50cc engine clone from 2005, to my bicycle. Do you know how sutainable they are? They seems to be as strong as modern trimmed moped engines, around 9hp. I would like to have an engine that is strong and sutainable. Do you know how mutch fuel they are drinking? If i am right, they do not have any gears, so what do you think? Do i need to ride at high RPM if i want to ride in about 35-40 mp/h if i ride with a 32 tooth sprocket or maybe even smaller? Is there any better engine i could use instead? Some Morini engine maybe?