The 1.1-mile track had all the horrors of a GP motocross track including daunting double jumps, tabletops and the odd tricky whoop. After an impressive but demoralising demo by factory rider Kevin Strijbos, I spent my first 20-minute session learning the track on the world's latest 57bhp/100kg four-stroke 'crosser.
My first thoughts were that it was like riding a MotoGP bike with slicks in the rain, but gradually I began to discover some traction. The torquey motor gives huge mid-range grunt, which means I used only third and fourth gear over a whole lap. Having a four-speed box has kept the engine crankcases slim, and combined with the flexibility of the engine power means there is no need to waste time continually shifting through the gears.
The engine has a distinctive bark compared to the competition and, if you can hold the throttle open long enough, it will rev beyond 9000rpm. Using hollow camshafts and titanium for the valves and exhaust header pipe has helped keep the motor's weight down, while fuel is inhaled via a 40mm flat slide Keihin carburettor.
Now it wouldn't be a proper Japanese product if it didn't have some good acronyms going on in the engine department, so the two main culprits this time are as follows.
The Suzuki Advanced Sump System (SASS) divides the sump into two
compartments - one for the
crankshaft, one for the transmission - and mounts the crank as low as
possible without compromising ground clearance. And the Suzuki Active Vent System (SAVS) is a clever breather system that reduces pressure underneath the descending piston, which in turn helps power output and throttle response.
The chassis size and dimensions are inherited from the two-stroke RMs, but the RM-Z450 has a new twin spar aluminium frame plus a wider swinging arm with thicker rear axle to cope with the biggest rear Bridgestone tyre available.
The fully adjustable suspension is by Showa, with 47mm forks and a rear shock with both high and low speed compression adjusters.
Even when I had picked up my pace the suspension still felt quite harsh, particularly at the front. But this could have been down to the lack of grip on the sandy track.
Meanwhile, brakes felt strong and consistent through the 250mm front and 240mm rear disc Nissin system.
I spoke to ex-GP factory rider Paul Malin on the launch who reckoned that for most riders a full factory bike would have very little advantage over the production model.
That said, Yoshimura can supply a whole range of tuning and suspension add-ons to improve performance so, although you might not lap faster, you will look like the dog's danglies.
A serious motocrosser I may never be, but I'll always have at least one off-roader in my shed. I'm not sure I'd ever master this one, so I'd plump for its friendlier sibling the RM-Z250. But if I were racing I'd want an RM-Z450, as I'm sure 2005 will see it collect silverware in abundance.
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