My son was out on his bike today and as soon as he tryed to kickstart it he knew there was a problem. took 8 kicks to get it going but as soon as he put it in gear it just stalled. It happened again twice so he had to do pritty much full revs to keep it going.He was half way down the field when the bike just backfired and just halted to a stop, (Sounded like a gun being fired), He tryed starting it but no luck. Checked the bike everythings fine, full tank, oils fine. I don't know anything about trials bikes so I have no idea what to do with it. Any tips on how to maintain a trials bike would be appreciated.