I just bought an 03 for my son. It started right up at the former owners house and ran great. We went trail riding in NH on Sat and it ran fine for the first 15 to 20 minutes then died. I tried to restart it but it felt like it had no compression. We towed it for the next couple of miles and it restarted right up. He rode it for another 10 minutes and it died again. Anyone have any ideas?