The engine is identical to the new mill housed in the CRF450R, with a finger rocker arm for increased valve lift, new piston, larger intake valves, and narrower included valve angle, but has revised engine mapping tuned for off-road riding. Whereas electric starting is a $650 option on the MXer, it comes standard on the RX, albeit with a heavy Grom-derived AGM (absorbent glass mat) battery. Fuel capacity has been increased from 1.6 to 2.2 gallons, but gone is the R’s trick titanium fuel tank replaced by a molded plastic unit. A forged aluminum sidestand is also fitted as standard.