An 8.3 litre fuel cell feeds the premium unleaded through to a 37mm flat-slide Keihin. The fuel/air mixture is then squashed against a heady 12.9:1 compression ratio before being burnt by a spark plug which resides between the forked exhaust rocker. Spent gases are then expelled via a stainless steel exhaust system which terminates in an upsweeping oval shaped muffler. The ADR muffler baffle is removeable for competition use.

Looking at the 249cc motor side-on, you can’t help but be amazed at the tiny proportions of the cylinder block and head. This is made possible by Honda’s Unicam design, first pioneered in this guise on the CRF450R. Simply, the single cam design has two cam lobes that directly actuating the titanium 31mm intake valves, while another lobe actuates a forked roller rocker arm which in turn opens the 26mm steel exhaust valves. The skirt on the forged piston is unfathomably short and slides through a diminutive 52.2mm stroke. The 78mm bore is NiCaSil plated.

Honda claim a 26.5kg dry weight for the engine complete with the heavier flywheel, extra gear for starter, starter motor and starter clutch. The kick start CRF250R engine is claimed to weigh just under 24kg, so very little mass is added by the addition of the starter motor and associated components on the CRF250X engine. But of course once you start adding lights and all the other associated street gear the overall dry weight of the CRF250X amounts to 110kg. This is 17kg more than what Honda claim for the motocross specification CRF250R.  It certainly hides that fact well.  The X model also scores a 20% larger cooling capacity to cope with long days in the saddle.

The engine pulls smoothly from everywhere in the rev range and best results are quite often obtained by short-shifting a little to take advantage of the mid-range. The last few thousand rpm are only really useful for over-rev when between gears. Even though we traversed through a variety of altitude changes the CRF250X just kept on keeping on, and never uttered so much as a cough through the airbox. It does seem to have the strongest bottom and mid-range power of the current crop of high-performance 250cc four-strokes. The top end has been noticeably knocked off with the less aggressive cam timing and a more restrictive airbox. But plenty of power is on tap for most situations. For those that really want top end at all expense, a CRF250R camshaft will set you back around $330, add to that a good pipe and some work to the airbox, and a fair bit more bite is added to the bark.

Honda provide a three-month parts and labour warranty on the CRF250X when the machine is not used for competition, but do remember that any of the aforementioned modifications will void your warranty cover.

A useful design feature of the powerplant is that the gearbox and engine oil reside in separate circuits, this helps to keep the engine oil free from clutch contamination etc. Most competition specification machines only offer small oil capacities, the CRF250X is a little more generous than most, however a strict oil change regimen is still mandatory to ensure good service life. The gearbox oil capacity is 750ml while a separate 850ml of engine oil gives lifeblood to the motor.  These numbers sound rather small, but believe it or not the CRF250X actually has a larger oil capacity than that enjoyed by any comparable machine.

The CRF250X is licensed for the road, however this doesn’t mean the machine is suitable for riding to work and back. This is a competition based machine and even in ADR form requires a very strict servicing schedule. If racing the machine you should change the piston and rings every 15 hours. If just trail riding, you are probably quite safe to plan your piston change every 1,000km. But if riding hard then stick to the competition schedule.  The price of a piston and rings is under $150 so it is fairly cheap insurance.

Of course one of the most important pieces of preventative maintenance that you can perform yourself is to ensure that your machine always breathes through a fresh pair of lungs. By that I of course mean the easy task of cleaning and oiling your air filter. This job is made even easier on the CRF250X as the airbox door is hinged. This means that if you carry a spare oiled filter on the trail in really dusty conditions, like all well prepared trail riders should, you don’t have to put the airbox lid down in the dirt when changing your filter. Good thinking Batman!

The eight-plate clutch seems sturdy enough to put up with plenty of abuse. The pull at the lever is just about right; it certainly is not too soft but at the same time never becomes tiresome. Thankfully most Japanese manufacturers have woken up to the fact that they can’t produce a decent set of dirt handlebars and now source them from specialist manufacturers such as Honda has done with Renthal. The bend felt just right for me and with the CR125R holders set in their middle position I found the reach also quite comfortable. The bars can be moved fore and aft through a 6mm range to further tailor the machine to individual rider preference. The bars are rubber mounted and I never experienced a problem with vibrations reaching my Fly gloved sausage-like fingers. Similarly the stainless steel pegs caused me no drama, and my Sidi size 10s had no problem with maintaining a good grip on them.

To be honest I never even gave the five-speed gearbox a second thought. To me this means that it must do its job very well as I can’t remember missing a shift, and I certainly never wanted for a ratio that wasn’t available. The gearbox on the CRF250X is a wide ratio unit while the CRF250R has a much closer set of ratios.