and how fast is sensible to learn on. Intention is also important, because the top speed of a street legal dirt bike doesn't mean much if you're planning on getting into motocross races.
Honda's lineup of 450cc four-stroke dirt bikes all wear some version of the CRF450 badge. The series includes the CRF450R, CRF450RWE, and CRF450RX supercross bikes, the off-road focused CRF450X ...