Go kart crashes happen, its part of the sport. It is very important to know what to do when it does happen. Remember your safety and the safety of the other racers should be your number one priority, not your kart. You can fix your kart, you can buy new body work, but you can’t just fix a major injury.
1) In the event of a flat of popped chain it is best to slow your speed by breaking lightly, get out of the racing line and have one hand up (if you have control) to indicate to the other racers that you are having issues and to either slow or pass. Remember if you are having any sort of issue with your kart it is safest to give up the racing line and let your competitors pass. Now carefully pull off the track entirely and pull your kart well away from the edge of the track (if you can). Even once your kart is pulled off the track you should stand even further away from the race. A safety vehicle will come and hep you.
2) In the event of a spin-out kart crash, if your kart is still in working order, get out of the racing line, and work on getting back into the race, once you are back up to speed continue racing.
3) In the event of a fire get out of the kart and get as far away as you can. The gas tanks are only plastic and will ignite (I have seen it happen). Whatever you do, do not try to put out any fire yourself.
4) Never fight another racer, regardless of who caused the go kart crashes. Officials will handle disqualifications after the race or black flag the offending driver. Fighting will only get you ejected from the race. No kart crash is worth that!