Relentless. Tireless. Tenacious. There are plenty of things you can say about the Honda TRX400X, but to fully understand it, you have to experience it. That’s because underneath the race-style bodywork lies everything the warrior ATV rider needs, starting with the SOHC, 397cc, air-cooled, dry-sump RFVC (Radial Four-Valve Combustion Chamber) engine.