In the engine room Honda engineers focused on making the machine tractable from idle through to the rev-limiter with the core focus on enhancing the already strong midrange. Don’t think for a minute all the top end has been sacrificed.

The machine still comes on cam fairly hard in the upper reaches of the digital tacho which very nearly caught me out a few times. The cylinder head and cam timing is also revised while more flywheel weight has been added to aid tractability. You certainly wouldn’t pick that last change. I would prefer even more weight added to the flywheel as a lot of clutch slip is required to keep the machine from stalling in tricky situations.

The changes to the cam timing sees the ‘X’ model’s intake valve open 5° later than the ‘R’ and closes 5° earlier. Similarly the exhaust valve opens 5° later but closes at the same time as that found on the ‘R’. The valves themselves are slightly smaller with the titanium intake valves 1mm smaller on the ‘X’ (35mm v 36mm) while the steel exhaust valves are also 1mm smaller at the face and are made from a new heat-resistant steel alloy. Honda does not have a recommended replacement schedule for the valves but states that clearance should be checked every 1000km.

The ultra short two-ring forged piston found on the ‘R’ model is carried over to the ‘X’ but benefits from an oil jet spray directed to the underside of the piston. Other changes include tougher big-end and main bearings with added thrust washers on the crank to further enhance reliability.

The intake plumbing has been revised to increase the intake velocity to further enhance low speed throttle response and boost midrange grunt.  This feeds the very trick Keihin 40mm flat-slide carburettor which is carried across from the ‘R’ model while on the exhaust side of the equation a longer pipe with a smaller internal diameter (38.1mm v 41mm) serves to boost the midrange even further. Amazingly Honda state that the CRF450X will run fine on standard unleaded and that their no real need for the use of premium fuel.

The motor is remarkably smooth and is free of the annoying vibrations found on most European equipment and also produces less vibes than comparable Japanese machinery.

One feature the ‘R’ model doesn’t have is the new electric starter developed for the ‘X’. A kick start back up is provided and is sometimes needed to be called upon however I never needed to use the hot-start lever in order to fire the beast into life and instead relied on the automatic decompression system to lighten the starting load. The fitment of the electric start has meant widening the cases but this has been kept to a hardly noticeable 17mm increase thanks to a thinner clutch pressure plate helping to offset some of the increase.

Another side effect of the move to electric start has been the removal of the oil sight window which would have been obscured by the larger generator required to power the ADR lights and stronger 48 watt charging system so instead the machine is fitted with a dipstick. The generator does seem to provide quite reasonable power as the sturdy 35-watt halogen headlight does not fade and glow brighter as the revs fall as is so evident on many European built machines. The tail light is a low draw LED inside what looks like a regular style housing which makes it look as though it is a conventional bulb inside but it is in fact and LCD.

Some clever thinking has gone into the cooling system with the system running at a reduced pressure to aid durability in the long term while the actual cooling capacity has been increased by 10%. A catch tank is now located out of the way behind the front skid plate. One rider did manage to hole the clutch cover with a rock and a larger purpose built plate would be a wise fitment for serious bush bashers. The radiators seem reasonably well protected by the shrouds but again it would be wise to fit some aftermarket radiator guards as cheap insurance.

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