X HITS THE SPOT
By TMX Archives on 14th Jan 10
DECEMBER is not a good month to launch a dirt bike into the UK market, but despite the dire weather Suzuki's new enduro, the RMX450Z, proved itself a surprisingly well-rounded package as JON BENTMAN found out
THERE was no question the new Suzuki was impressing. Turning it across the field, despite the slick conditions, it would confidently power slide in third gear, digging deep into its voluminous power and digging deep into the soil to find enough traction to almost start lifting the front.
It was hauling, and with gearing that would take it to a indicated 75mph (seen on the tarmac, not in the field) there was enough motor to please any speed freak. But this isn't what impresses with Suzuki's new enduro; it's how it behaves elsewhere, in the tricky going in the woods, over the roots and rocks. It may be born from a motocrosser, but the RMX450Z is a pukka enduro weapon.
Being a Japanese-made enduro bike its strength isn't in any one particular aspect, rather the sum of its parts. It combines a great chassis, supple suspension and an authoritative yet forgiving power plant to create a ride that even the humble clubman can enjoy. For a while now the British enduro scene has been looking at 450cc four-stroke enduros as an Expert-only tool, and even the Experts are reluctant to use them (preferring 250cc two-strokes, or over-bored 250Fs as their E2 weapons of choice) but there's this possibility that the RMX450Z might just change our way of thinking.
As said, the motor is sublime. Where the motocrosser RM-Z motor from which it is derived is necessary punchy and would be a real handful in the woods, the re-tuning of that motor into RMX guise is inspired. With a significantly lowered compression ratio, 'softer' cam profiles and vastly altered ignition timing you can barely recognise the lineage. The throttle picks up from nothing and in one long, dare we say linear, pull, it simply goes and goes. And it's all serious hoof, rather than just revs for the sake of revs. It feels smooth too, not at all 'raw'.
Matched to this is a well thought-out wide-ratio gearbox that extends both lower and higher than the motocrosser's gearbox which means you can trickle trials-style through the tricky stuff - teasing at the traction - or quite easily punch through the national speed limit. The real trick though is doing that without leaving gaps somewhere in between. And we have to say the RMX not only has every base covered, but it seems to have the breadth of power that allows a choice of at least two gears for every situation.
So, combining the engine characteristics with the transmission, the feeling is the power is luxuriously long, torquey and smooth - where the likes of KTM's 450EXC will feel punchy and fast revving. It's not an entirely new take on 450F power but the fact Suzuki has resisted going for the highest horsepower score and instead clearly focused on making a useable and accessible power plant, that's going to work in such a varied range of conditions, deserves high praise.
Of course, the RMX also comes with fuel injection. And very good it is, too. The fuelling was exemplary, and whereas in years gone buy fuel injection could have been typified by sudden on-off actuation and a reluctance to take a steady throttle, on the RMX it was virtually impossible to fault, never bogging, and always there to answer every call and with every sense of fine modulation.
The chassis is based on the 2009 RM-Z450 and, like the motor, has made the transition from track to trail with refreshing ease. It's motocross base means it's seductively slim and suitably minimalist. It's a comfortable ride, though, and once we'd rolled the bars forward in their clamps it offered plenty of room for a six-foot rider.
Suzuki has done what feels like an excellent job on the suspension. Despite looking to all intents identical to the motocrosser's Showas, the spring rates are a good deal softer and Suzuki has adjusted the valving and even the oil levels to attain an appropriate level of plushness to work in the woods.
For this test, in pretty slick conditions, the set-up felt very confidence inspiring. The RMX could be easily guided to cut diagonals over ruts, could be turned off a bank like a 250 and similarly would track neatly over roots. The bonus is Suzuki has two further alternative options on fork springs and four alternatives on shock spring. Combined with various recommendations on the fork oil level, there's a healthy range of settings, which should suit everyone from the Welsh to the Eastern Centre.
All up, the RMX450Z is a very impressive piece of kit. It combines a lot of hard won enduro traditionalism - easy-going but strong power, supple suspension and unfussy construction - with new age benefits like electric start, programmable ECU and fuel injection to make for a bike that is bang up to the minute.
Before this test we feared we were going to find a barely modified motocrosser that would be too wild for anything but the fastest of cross-country tracks. Or alternatively the formula would be so watered down as to be lamb born of a wolf.
As it goes, on first feedback Suzuki has instead scored a direct hit. It shouldn't be forgotten that Suzuki developed the ever so successful PE range back in the 1970s and '80s and followed that up with the capable RMX250 in the '90s.
Well, Suzuki may have been absent in the noughties - the DR-Z being a trailie not a competition bike - but by hell they're back for the, er, tens.
WE LIKE:-
- Quiet exhaust as stock (82dB) that still stays reasonably silenced when unplugged for more power (we tested the bike unplugged).
- Good strong starter motor that showed no signs of weakness. Kickstart worked well too.lThe instruments were both easy to read and useful in the details they offer - including a trip meter that reads in tenths and a stopwatch.
- Airbox design is spot on. One Dzus fastener and one spring clip is all it takes to release the filter.
- Clean design - although we rode in some slick going the RMX didn't get too hung up with mud.
WE DON'T LIKE:-
- Biggest concern is the 6.2-litre tank. It'll probably be okay for enduro, but cross-country racers might find they'll need one more refueling stop than they'd like. Trail riders definitely won't be happy with the capacity.
- The side-stand works very well and is sturdy enough, but it's big, clunky, doesn't tuck away and (alone) loves to collect mud.
- If we were trail riders we wouldn't appreciate it not being properly homologated. But with most races being closed-course and with dealers able to road-register bikes based on daylight MOT specs, on balance a lack of road compliance isn't so bad.
TECHNICAL SPECIFICATIONS
2010 Suzuki RMX450Z
ENGINE
Type: Liquid-cooled, single-cylinder, DOHC four-stroke
Bore x Stroke: 96.0 x 62.1 mm
Displacement: 449 cc
Compression Ratio: 11.6 : 1
Fuel system: Fuel injection
Starter system: Electric
Lubrication system: Semi-dry sump
Clutch: Wet multi-plate type
Transmission: 5-speed constant mesh
CHASSIS
Type: Aluminium twin-spar type with
aluminium swinging arm
SUSPENSION
Front: Showa 47mm telescopic forks, pneumatic/ coil spring, oil damped
Travel: 310mm
Rear: Link type, coil spring, oil damped with Showa piggy-back-reservoir shock
Travel: 310m
BRAKES
Front: 250mm disc, Nissin twin-piston caliper
Rear: 240mm disc, Nissin caliper
TYRES
Front: 80/100-21 51M
Rear: 110/100-18 64M
DIMENSIONS
Overall length: 2,185 mm
Overall width: 840 mm
Overall height: 1,265 mm
Wheelbase: 1,485 mm
Ground clearance: 320 mm
Seat height: 950 mm
Kerb mass: 123.5 kg
Fuel tank: 6.2 litres
FOR FULL TEST REPORT SEE T+MX NEWS, FRIDAY, JANUARY 8, 2010
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