Blowouts are not only caused by patched tires. I forgot which year, team, rider, stage, ... of tour de france this happened, but I remember reading about a blowout on a TT stage once.

Reading about fixing flats on a motorcycle, I found this http://www.instructables.com/id/Moto...Flat-Tire-Fix/
It's much easier on tubless tires, but most MX bikes have spoked tires, so fixing a flat has to be done the hard way.. take the wheel off, and then it's all really similar to a bicycle.