I had 3 wheelers. honda ATC200X, ATC350X, then ATC250R. the 350X would hurt ya and 250R was flat out beyond dangerous, CR250R power plant on 3 wheels.
later on, bought a TRX400EX 4 wheeler and lost a day of my life after faceplanting getting about 10' of air from a jump with no helmet on.
my bro had a 2 stroke 125 dirt bike when i was a kid. watched him crack the throttle to jump a little hill thinking the gate at the top was open . . . it wasn't. ran straight through the gate and put him down pretty hard. he laid there for a bit before we got him to come around. again, no helmet.