2010 Honda CRF250R boasts EFI, new engine and chassis
By, Trevor Hedge
Honda’s CRF250R is Australia’s top selling motocross bike and with a new engine complete with fuel injection, that trend is almost certain to continue.
Honda has really done a sterling job with the CRF in the last few years. Only five years ago the sight of a red bike on Australian motocross tracks was a rarity. Yamaha and KTM had done such a brilliant job in the transition to four-stroke machinery that just about every bike seen on the tracks was either Yamaha blue or KTM’s signature orange. That situation has clearly been turned around now and Honda is more than well represented in every state championship motocross round or enduro event. To be fair, Kawasaki has also recently made huge inroads in the sector and Suzuki is also starting to have a stronger presence.
To be honest, I considered the dominance of the blue and orange bikes a few years ago to be almost impenetrable, and I really doubted whether Honda could actually re-establish their #1 status in the motocross market. The fact that they have managed to do exactly that is obviously down to a good product, good marketing and the stunning good looks that the very fashion conscious motocross market demand.
The standout feature of the original CRF250R was the incredibly compact powerplant. The complete engine-gearbox drive-train weighed in well under 30kg and featured an incredibly short piston that almost beggared belief.
For 2010 Honda claim the engine is even more compact and have used an even shorter forged piston. The thinner piston also slides through a longer stroke. The 2009 CRF250R had a 78mm bore and 52.2mm stroke while the 2010 machine measures in at 76.8mm by 53.8mm. The crankshaft sits 10mm lower.
The compression ratio is also marginally higher, from 13.1:1 to 13.2:1.
The titanium intake valves have shrunk marginally from 31mm to 30.5mm and the steel exhaust valves are down from 26mm to 25mm. One would imagine this is a move to help increase the speed of both the intake charge and exhaust charge and as a result further boost low and mid-range grunt. The CRF250R is already well renowned for its great bottom end pull so the new machine equipped with a longer stroke would seem to suggest the new bike will be even stronger in the mid-range. No doubt EFI will make the machine’s delivery feel a little softer than the sort of instant snap derived from a flat-slide carburettor but it should also lead to faster lap times and make the machine easier to ride.
The ‘all new’ engine obviously follows the same Unicam valvetrain design as its predecessor and is now fed by a 50mm EFI throttle body with a single 12 hole injector. As before a single camshaft directly actuates the intake valves while a centre lobe pushes on a forked roller rocker arm to open the exhaust valves.
At 50mm the size of the throttle body will surprise many. Suzuki’s new RM-Z250 makes do with only a 43mm throttle body and the carburettor of the previous CRF250R was only 40mm. This seems somewhat at odds with Honda’s aim to concentrate their killer punch in the mid-range delivery rather than the top end but I guess the proof will be in the pudding, as they say.
The intake ports are now straighter and Honda also makes mention of ‘a new ultra high-strength material’ derived from MotoGP in the metallurgical properties of the valves.
Honda are claiming an output of 43.3hp @ 11,000rpm with maximum torque arriving at 8,000rpm and peaking at 29.3Nm.
Thoughtfully, the connectors for tuning of the EFI system are located behind the radiator shroud for easy access. Also behind those new radiator shrouds are larger radiators to improve cooling performance.
The AC generator has been enlarged to cater for the demands of a 50psi fuel pump and to power the associated EFI sensors. Two crank angle sensors are claimed to help both hot and cold starting which of course is always helpful when starting is by kick only. The auto-decompression system has been revised and the kick start ratio changed.
There is also no battery which effectively means that through the kicking process capacitors are charged enough to activate the fuel pump, injectors and ignition systems.
An improved ware pump seal and special coatings on the clutch basket are other evolutionary changes employed on the new engine.
The gearbox ratios are also changed to suit the characteristics of the new powerplant. The input and output shafts are also now further apart which has allowed the use of a larger and therefore tougher gear.
On the chassis front there have also been plenty of changes. The twin-spar aluminium frame is narrower, 26mm versus 27mm, the spar height has been reduced from 70mm to 66mm and is equipped with a forged steering head and stronger downtubes.
The front wheel is now positioned 15mm further rearward and closer to the crankshaft in the aim of improving steering response and handling, and the triple clamp offset has shrunk from 22mm to 20mm. The more aggressive steering would normally result in a machine that is far too twitchy and unstable but that should all be taken care of by the progressive steering damper. Aiding traction is a 29mm longer swingarm and the aggressive steering characteristics are somewhat offset by a slightly longer wheelbase.
Showa supply the inverted cartridge forks that at 48mm are 1mm larger than before but offer the same 16 rebound and compression adjustments and 310mm of travel. The forks have 24mm cylinders and Honda have used new fork oil to further improve performance and the springs are shorter than before. A ‘Kashima’ coating is also applied to the fork internals.
Showa also provide the single shock which affords the same 17 stages of rebound and compression adjustments as before but at 320mm has 15mm more travel along with new damping settings and spring rates to match. A large 50mm piston helps to reduce fade.
The removable rear sub-frame has been altered in shape to improve access to the air filter and larger air-box and eliminates all brackets. The new frame has allowed for larger intake ducting to the airbox which also facilitates much easier air filter servicing.
The fuel tank has shrunk from 7.2 litres to a meagre 5.7 litres. Honda are claiming that the improved fuel economy delivered by EFI has enabled them to get away with such a small fuel cell.
Ready to ride complete with a full tank of juice, the 2010 Honda CRF250R tips the scales at 100.7kg. This is around 1.5kg less than before, but with 1.5 litres less juice onboard the new bike realistically weighs roughly the same. This is pretty good going considering the extra hardware required by the fuel injection and HPSD systems.
The trademark dual muffler layout of the CRF250R is gone for 2010, replaced by a single muffler located as centrally to the bike as Honda could manage in an effort to further enhance their trademark ‘mass centralisation’ principles. The single muffler also realised an 850 gram weight saving.
As we went to press Honda Australia could not accurately advise the expected arrival date of the new CRF250R but have indicated that the model will be on sale before Christmas. And who wouldn’t want a shiny new CRF250R for Christmas!
— Click Here for images of the 2010 Honda CRF250R
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—Â Specifications – 2010 Honda CRF250R
— Click Here for images of the 2010 Honda CRF250R |