Suzuki RM-Z250/RM-Z450 (2011)
If there was one dirt bike manufacturer which could feel justified for leaving its stable of motocross weaponry unchanged for 2011 it would be Suzuki. After all in 2009 the RM-Z250 destroyed the Aussie Pro Lites class (both motocross and supercross) in the hands of Matt Moss, and since then Ryan Dungey has grabbed the US scene by the throat, blowing all others into the weeds (both indoors and outdoors) on his RM-Z450.
Add to that victory in the 2010 Australasian Dirt Bike magazine’s 450cc MX shootout and the old adage “if it ain’t broke, don’t fix it” begins to hover on your lips. However the yellow brigade knows well that to stand still is go backwards in such a highly competitive market.
Rather than reinventing the wheel, for 2011 both bikes build off the strengths of their predecessors with a range of refinements from engine to suspension aimed at ensuring the RM-Zs continue to fight for purchasing dollars and podiums the world over.
It was a cold winter’s day when Rockstar Motul Suzuki team boss Jay Foreman rolled out the latest offerings for us to throw a leg over at Wollongong’s Mt Kembla motocross facility. Did they meet our expectations? Read on to find out.
2011 SUZUKI RM-Z250
While last year’s two-fiddy ‘Zook ticked most of the handling and suspension boxes, it was its first foray into fuel injection and the quarter litre engine was as soggy as a microwaved pie. No wonder then that the bulk of the changes to the 2011 model have been aimed at pumping a few more ponies out of the 249cc DOHC donk.
Bottom end and midrange power has been boosted thanks to new cam timing (for both intake and exhaust valves) coupled with a new ECU map.
After valve-bouncing his bulk around the obstacle-rich Kembla track, retired-Pro Paul ‘Broomy’ Broomfield was impressed. “I liked the bottom end – you could run tall gears through turns,” he enthused. “You needed to use a bit of clutch on the way out but that’s par for the course for a 250F.”
That said, for heavier riders like Broomy and myself an extra couple of teeth on the rear sprocket would help pull the bike out of tighter turns where the sweet spot often sits somewhere between second and third.
Suzuki claims the cam-timing changes also improve the little RM-Z’s over-rev ability. While she may be happier revving her tits off, according to Foreman’s preliminary dyno runs she makes the same power up top as last year.
Nice to know (but impossible to tell the difference from the saddle) was wider third and fourth cogs in the gearbox for increased durability, re-routed radiator hoses for better cooling efficiency and better clutch lubrication.
Hands down the new RM-Z250 is one of the sharpest handling bikes we’ve ever ridden. It falls effortlessly into ruts and turns, is super light and flickable in the air and yet highly stable at speed and under brakes.
Last year’s 250 was a little over sprung which Suzuki has addressed with lighter spring rates and revised valving. While a big plus for lighter riders, good bottoming resistance meant even heavier blokes like us could still confidently launch the biggest jumps on the Kembla circuit without fear of a nasty slap-down. It’s a plush and pleasingly balanced package that will be right on the money for most riders straight out of the box.
2011 SUZUKI RM-Z450
It’s got to be a bloody tough job trying to make a class-winning machine even better yet that’s exactly what Suzuki has done with their flagship 450cc motocrosser.
Power has been subtly increased right across the rev range, now peaking at an impressive 39.5kW (53hp) – one horse more than last year. Where it gets the extra boost is from a higher 12.5:1 compression ratio (0.3 up from ’09) combined with revised cam timing and ECU mapping, while still managing to stay under the 94dB competition noise limit.
Through the twisting turns and extreme elevation changes of the Kembla layout, all that horsepower was nothing short of awesome. Third gear is almost a case of “set and forget” as it would happily lug the bike out of all but the tightest ruts and only revved out towards fourth gear territory in a couple of places on the track . That fabled wrist-to-rear-wheel connection is still one of the bike’s best assets.
One rider on the day commented that the big ‘Zook felt a bit lean up top. This was to be expected in the bitterly cold winter conditions but an easy fix with the richer ECU plug option which comes in the spares kit. A leaner plug is also on standby for those in higher or warmer climates.
Throwing the RM-Z into turns and ruts is almost as easy as on its smaller 250F stablemate. Attack a corner with confidence and it will blast through with the nostril-flaring fury of a race horse. It’s a bike that rewards a purposeful pilot while still being manageable in less experienced hands.
At first the suspension balance was a little off on the 450, with the front harder than the rear. A quarter-turn on the shock preload and a couple of clicks softer on the fork would be all it took to even things out and smooth the ride through the harsh choppy bumps.
“It has a long and stable feel to it” offered Broomy. “Around here you’re getting some speed up and you’re not going “Shit what’s it going to do?” That’s saying something as there’s some slick spots out there where you can lose the front or the back and I had a lot of confidence in it.”
The small details haven’t been ignored for 2011 either with re-routed wiring to mimic the 250’s tidier harness and lighter titanium footpegs replacing the steel units of yesteryear.
“It’s far and away a better bike straight out of the crate than my project bike in 2008,” beamed Broomy. “Once again what they’ve done with the 2011 is massage what was already a bloody great bike.”
2011 SUZUKI RM-Z250
– Different cam timing, crankshaft and ECU map
– More bottom and mid than last year’s bike
– More durable third and fourth gears
– Improved clutch lubrication
– Softer spring rates and revised suspension valving
– New silencer for the 94dB noise limit
– New kickstart bend
– 2011 Suzuki RM-Z450
– Different cam timing, crankshaft, ECU map and higher compression ratio (12.5:1)
– RM-Z250-style wiring harness
– Rich and lean plug option to customise mapping
– Titanium footpegs
Type: Liquid-cooled, four-valve, DOHC single-cylinder
Bore x stroke: 77 x 53.6/96 x 62.1mm
Fuel system: EFI
Type: Five-speed, constant mesh
Final drive: Chain
CHASSIS AND RUNNING GEAR
Frame type: Twin spar aluminium
Front suspension: Showa 47mm, fully-adjustable, inverted fork
Rear suspension: Showa fully-adjustable link-type monoshock
Front brake: 250mm wave disc with Nissin two-piston caliper
Rear brake: 240mm wave disc with Nissin single-piston caliper
DIMENSIONS AND CAPACITIES
Kerb weight: 104.5/112.0kg
Seat height: 955mm
Fuel capacity: 6.5/6.2lt
Bikes supplied by: Suzuki Australia
*Manufacturer’s list price excluding dealer costs