Honda CRF450R

Honda's new four-stroke motocrosser, the CRF450R, has been a long time coming. Some three years after people 'in the know' predicted a response to Yamaha's all-conquering YZ400F from Big Red, the first of the machines has landed in Australia for promotional and media duties, prior to its market release either at the end of this year or early the next.

As such, spares for the CRF are at this stage non-existent - prompting Honda's Marketing Manager Rhys Griffiths to inform me at the media day that should I damage the CRF in any significant way, my life would be duly terminated. Inspiring stuff.

My already shaky confidence didn't improve after looking at the Hartley track that I was going to explore the CRF450R's depths on - it was the roughest, bumpiest, gnarliest circuit I have ever been on (the fifth round of the ADB Thumper Nats had been run and won on it the previous day). I was getting arm-pump just looking at it!

Riding the track on the O'Neal Honda Racing team XR650 Thumper and CR250 prior to riding the CRF only served to prove my eyes weren't deceiving me, this track was ROUGH!

How the hell was I going to give this bike a decent going over - without Honda putting a bounty on my head and/or embarrassing myself in front of one of the most professional race teams in the country?

Well, I'm still here - and this is mainly thanks to the CRF450R. The new bike combines proven suspension and frame components with an engine that is both exciting and manageable - I immediately felt comfortable on it.

While this was by no means a definitive test of the new jigger (I had to share it with other journos) I got enough of an idea to say that it is very impressive - especially considering it is an all-new model.

LENGTHY DEVELOPMENT
While I say all new, development has been a lengthy one, with riders the calibre of American Ryan Hughes campaigning the machine for Honda in prototype form - and doing pretty well too!

This development must have been on the right tram, because this bike feels like it is right up there with the competition from the word go; no mean feat by any standards. I know the O'Neal Honda boys can't wait for next year...

The bike's twin-spar aluminium frame is derived from the CR series, and is a third-generation design. Visually, the main difference between it and the CR250 frame is the front downtube, which is a slightly larger diameter.

The abundant welds on the frame are of Honda's usual high standard, including the ones attaching the spars to the forged steering-head. The bike steers very well - another Honda dirtbike trait - and the claim of a 102kg dry weight (Yamaha claims 105.5kg for its YZ426F, KTM 107kg for its 520SX) felt about right, but we will have to wait to put it on the scales to be sure.

The CR250R-derived 47mm USD Showa forks are certainly firm, this is after all a motocross bike, however the CRF450-specific settings allow big, square-edged bumps (and there were plenty of them) to be soaked up reasonably well without bottoming out during my short ride. And yes, the 20-inch wheel option is available (21-inch standard).

TRACTOR TRACTION
The rear Pro-Link Showa shock also performs well, aiding in the impressive tractability the CRF exhibits, and includes high and low-speed compression damping adjustment.

Gassing up any bike hard over choppy ground is always a good test of rear suspension, and the CRF coped well - maintaining well controlled drive through the rear Pirelli (Dunlops will be the OEM tyres), without swapping all over the place, and again without bottoming.

One corner in particular which I had found tricky on Cameron Taylor's CR250 two-stroke racebike, a slippery flat left-hander, was a piece of cake on the CRF450.

The traction available meant I could keep the power on through the slippery part - feeling exactly what the rear wheel was doing - before smacking the back wheel into a berm, squaring off and firing myself at the next corner. On the two-stroke it had been softly, softly.

While this improved traction is a function of four-stroke power delivery over a stroker, the CRF does it particularly well, with a rear end more controlled than Yamaha's YZ426F.

Speaking of power delivery, the new engine is a beauty. The 449cc liquid-cooled, four valve, Unicam (SOHC) powerplant is tiny, with crankcases that wouldn't look out of place on a 250.

The small size and magnesium rocker and clutch covers are part of the reason why Honda is able to claim an engine weight of 29.7kg. Also contributing is the 'Unicam' valve train - in other words a single camshaft in place of the usual two. What's old is new...

What is new is the twin-sump design, keeping the gearbox and engine oil separate. The benefits Honda claims include keeping a cool supply of oil to the clutch (thereby reducing clutch wear) and keeping clutch and gearbox contaminants separate to the engine.

EASY STARTER
Starting the beast is no problem either, despite the high 11.5:1 compression ratio. What looks like a manual decompression lever is actually a hot-start lever. Decompression duties are looked after automatically, though there is a manual system available as an option, and Honda will run one on the racebike.

"What's the starting procedure?" I asked Pip Harrison, Honda's technical guru. "Just kick it 'til it goes," he replied.

No finding top dead centre, no grimacing appropriately, in fact no 'procedure' at all. The bike started first or second kick every time hot or cold, using the hot-start lever when necessary. Easy.

Once Pip was happy the bike was warm, I was allowed to move onto the track. One thing immediately noticeable was the sheer torque of the thing - Honda claims nearly 5kg-m at 7000rpm, but there is plenty down low as well.

Rolling wide open the super-precise throttle unleashes a claimed 55ps at 9000rpm, and things start to happen pretty quickly - such as trees getting closer, the front wheel hoisting, velocity increasing et al.

Luckily, the Keihin 40mm flat-slide carb's light action allows the rider to meter out the power appropriately. In fact the throttle control was one of the main reasons I felt so comfortable riding the CRF; gnarly track conditions and all.

What this means for clubman-level motocross riders like me is that you can still get around at a reasonable pace using the bike's seamless bottom to mid-range torque.

An eight-bit digital CPU, incorporating the CDI, no doubt helps here, keeping the throttle crisp at all openings. And once it is fully open, hang on tight!

All that horsepower combined with such impressive traction blurs the scenery in short order. This thing hauls, and will keep Pro-level riders happy in this mode.

Whether or not it has the top-end of the YZ426F, or even KTM's 520SX remains to be seen, but it must be well and truly in the ballpark.

GETTING SQUEEZY
I didn't notice any undue vibration from the engine (though the track was rattling my teeth) and the five-speed gearbox shifted cleanly every time via the smooth action clutch.

The ergonomics on the CRF are well thought out, and moving around on the bike is easy as a consequence. I was able to sit well forward to help the bike steer even better, and the bike's narrow girth helped promote a feeling of control. It didn't feel much different from the two-stroke CR in this regard.

Something else the ergonomics allowed me to do was use my weight in a vain attempt to keep the front wheel in contact with terra firma. This was especially important exiting turns on a surge of torque, or when practising race starts.

The race starts I tried in second gear proved that there's plenty of traction and grunt off the line. A little too good in fact, as keeping the front end down is a bit of a mission. As they say though, practice makes perfect.

Hauling down all this forward motion is a single 240mm disc up front, squeezed by a twin-piston caliper. It's backed up by a new HRC works-type rear system which incorporates the master-cylinder with the fluid reservoir. The rear disc is also 240mm, while the caliper is only single-piston.

Thankfully, the stoppers are more than up to the task. Initial bite is strong without being too aggressive, and the power is easily modulated through the adjustable lever.

WORKSHOP MANUAL
According to Pip, the bike is really easy to work on. Access to the air filter is simply a matter of removing the seat (two bolts), while the twin oil drain plugs are positioned with regular maintenance in mind.

By all accounts the bike should be easy to live with, though I will have to wait for a full test before passing judgement in that direction.

Riding the bike back to back with Cameron Taylor's XR650 was an interesting exercise, as it highlighted the differences between a 'traditional' four-stroke dirtbike and the new breed of super-sharp, super-responsive motocross scalpels.

While the XR650 in race form is still a competitive Thumper Nats racer (Cameron had scored a fourth and two thirds the day before in the Pro 650cc class, not to mention Michael Byrne's pair of seconds), the CRF450R is something else again.

Its lighter weight and superior handling stands the bike in good stead for next year's Thumper season, not to mention giving Honda a competitive bike in the rapidly developing open class of the World Motocross Championship.

It has been three years coming, but it was worth the wait. Honda's open class four-stroke motocrosser is here, and has quite possibly raised the bar in the process. I am looking forward to a more thorough sampling.