i bought a my bike from a guy that said he just had it tuned up. rode it for a day and a half then it broke down. a hole was knocked into the piston. aparrently some teeth broke on the belt which caused this. ive stripped it down ordered a used head an valves, pistons, cylinder jug. i got it all back together an it wont start. it backfires out the airbox an thats it. can i get some advice. i got a job interview to beat monday morning.