The RM-Z450 is Su Su good
By TMX Archives on 9th Apr 08
AT the end of November T+MX News chief motocross tester Johnno White was among a select group of riders invited to test the all-new Suzuki RM-Z450 at the famous Valkenswaard GP circuit in Holland. Although he came away hugely impressed with the ground-breakng new fuel-injected machine, Johnno was only able to run two short 20 minute test runs on the bike and gather just a brief impression of the bike. Very keen to really put the bike through it's paces properly and fully discover what an EFI shod machine was capable of T+MX was right on the case to organise a full test of the RM-Z450 on UK soil whilst at the Stoneleigh Dirt Bike Show.
Delays in the arrival on UK soil of the much anticipated machine kept us waiting for a bit longer than we hoped, but as soon as Suzuki GB was in possession of test bike Suzuki's long-standing motocross team manager Rob Hooper and Suzuki GB's Luke Plummer were on the road and met-up with Johnno for a second bite of the cherry at the superb Leisure Lakes facility near Southport. Over to Johnno for his thoughts after a full day of putting the bike through it's paces on the almost Dutch like sand track...
IT IS the look of the bike that first takes your eye in showroom or at a track and as far as the overall look of the new RM-Z450 is concerned I think Suzuki deserve ten out of ten.
It's not a radical re-vamp, but the new alloy tank and dark blue rad scoops slip in to the new frame perfectly, and the front-end has a really cool front fender and number board combo that gives it a very distinctive, and very factory look. To that end the bike also comes with wavey discs as standard and thanks to the trick looking 'power-bomb' section on the header pipe which helps keep noise limits down the bike can also afford to run a relatively small silencer and still hit the 94dba limit, which gives the bike a much more balanced and compact look than it would if it had some huge hunk of metal hanging out the back. Even the foot rests look like they have been robbed from Steve Ramon's bike because they are so wide and factory looking.
Out on the track I felt at home on the bike straight away, not only because I had ridden it recently - albeit very briefly - but also because it is a very neutral, comfortable machine and very easy to get on with. As the bike was brand new I gave it ten steady laps just to bed-in then I started to put in some faster laps and almost right away I found the fuel injected 450 amazing. There is abundant power all the way through the rev-range and it is delivered very smoothly all the way through with no sudden hits or jumps in performance. Low-end power in particular is very good indeed and the move up to a five-speed box too has helped with this and the gearing just feels that bit more even and lends to a smoother ride.
The fuel injection system has definatly made a big improvement over the last years model, and certainly elevates the RM-Z motor to a position where it could be viewed as the best all-rounder in the class.
All the claims the tech types have made over the years that EFI would result in smoother power, clean power delivery and instantaneous throttle response have been made reality with the Keihin unit Suzuki has fitted to the machine, and the resut is both eye-opening and very impressive. The whole motor feels revitalised and significantly improved, but where the fuel injection has given this bike a boost is in the actual delivery of the power the bike makes. Throttle response is actually instant. Not almost instant or just an imporvement on a carb version, but instant. Now in the deep Dutch-like sand that abounds at Leisure Lakes this is not as hugely noticable as it would be on a hard-pack or laomy track, but it is still very impressive, particularly in those situations where a quick chop off the throttle and back on again is required. Like I said though get this bike on a more hard-pack track and out of corners, landing from jumps and out of the gate you will really notice how much better and EFI machine responds to your input at the throttle. The big selling-point of EFI to me though is just how clean and strongly it gets the motor to run, no matter what the situation.
There are a lot of long, deep sweeping corners on the Leisure Lakes circuit and thanks to the EFI unit I felt that whichever gear I was in the RM-Z450 pulled like a train without any trouble.
Because the EFI unit constantly adjusts the fuel delivery I was able to carry taller gears like third and fourth in areas where I would have struggled on a carburated bike without any sign of engine strain, coughing or bogging. And this wasn't necessarily on full-throttle either, and it wasn't just on the faster turns the EFI was noticable either. I ran through a deep medium-speed 180 degree left in every gear from second to fourth numerous times and no matter what gear I was in the EFI compensated and pull strongly and smoothly. This is hugely beneficial in that it takes considerably less effort to get the bike around the track as a result. Four-strokes have always required a less precise riding style than two-strokes anyway, but the RM-Z450 takes it one step further and really allows you to get away with things that previously you couldn't if it comes down to it. Obviously to get the optimum performance and power from the bike hitting your lines and getting your gear selection spot-on is the way forward, but if you do mess up and come into a slow corner a gear too high or you are just getting tired and trailing the throttle the RM-Z450 has the ability to get you out of trouble and keep your momentum up better than any other bike on the market. It's a real boon for your average clubman rider in particular.
Given how well the bike coped with the 50 tooth standard rear sproket I would be tempted to run a 48 or 49 myself. The bike would cope equally well out of turns I think, but just give the bike that bit more length in each gear, make it even easier to ride and possibly eliminate the need for an extra shift in some situations too.
One sweet side-benefit of having an EFI system is that starting the bike was an absolute pleasure and almost effortless.
From cold I found it easiest to turn the engine over three times slowly then one final kick and it fired in to life, this enables the fuel pump to activate because it doesn't have a petrol tap like other bikes. As far as starting the bike when it was hot was concerned, it was just as easy. find neutral, engage the hot-start lever and within one of two prods it fired-up. Excellent news for knackered riders everywhere.
Although with the likes of Ricky Carmichael, Steve Ramon and others on the company pay-roll it is clear that the new RM-Z 450 has been developed by some of the best riders in the world and with the aim of building one of the fastest, most impresive motocross bikes ever, and they have achieved that. However, Suzuki has definatly tailored the bike to suit all grades of rider because despite the immense grunt this bike has it would suit a Junior who just wants to do his local AMCA events or a British championship rider who wants to compete with the best. This bike definatly has it all. Before you really notice the benefits of the EFI system though, the first thing that really stood-out to me was how much the chassis design has improved and as a result how much more comfortable and stable the bike feels, and how easy is was to corner. The new frame provides a much more responsive and forgiving ride than the previously quite harsh incarnation and combined with the new body work and seating position has definately made a big improvment on the overall handling of the bike. It holds lines better, turns shrpaer and just generally feels light and more responsive.
The front -end in particular was very impressive and the new front forks worked faultlessly. I found the valving was great and on one section of the track in particualr I could really put it to the test, push the front harder and harder to try get it to wash-out, but lap after lap it tracked perfectly no matter what which shows that the valving and spring rate are pretty much perfect for your average weight rider right out of the crate.
The rear-end was not quite as good as the front; the rebound was a little bit too quick for my liking and possibly a little bit soft on the compression. Obviously though only a few minutes and a few clicks either way would remedy this on the kost part and in general I felt the rear-end tended to follow the front well and made the overall handling of the bike almost perfect. It is a formidable chassis indeed.
Overall the 2008 RM-Z450 is a fantastic bike and although it has been a long-time coming, those who have waited to purchase one will definately not be disappointed. This bike has everything; a sharp chassis, sweet handling, a superb motor and a genuinely ground-breaking new development. In years to come I think it will be seen as a key mchine in motocross development.
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