Ok, so I just started to run my motor when it stalled today. I tried to restart it and it wouldn't start. I checked everything. I spun the flywheel to see if the motor is blown and it has some resistance. when i try to start it, it will sound like it wants to start and then there will be a backfire sound. I tried tuning the needles, checked the glow plug and it all looks good. Could it be blown?