ok so today a bunch of buddies and i were getting ready to play some kickball on the bikes and i was just riding back and forth waiting i was riding to the other end of the field and the bike just died on me so i figured no big deal ill just kick it and it will start up again. well not the case couldn't hardly turn the motor over and then it locked up could kick it at all. i know that after ever so many hours the motors need rebuilt but its supposed to be after 40 hard hours and the motor was just rebuilt before i bought it and i had maybe 10-20 hours on it. also i had just changed the oil last night. both sides and this was the first ride on the new oil. so my question is what is the average cost of an engine rebuild? and do you think that it will need a total engine rebuild?