It’s been a long time between drinks in production motorcycle innovation. Realistically, the last significant innovation was the four-stroke. Before that, upside-down forks.
Before that, disc brakes, then watercooling, then single-shocks. Not much else going on since my hairy uncle came out of a tree. Hence a serious case of kid-at-Christmas EFI antici… pation here at MTN Towers.
There’s no doubt that fuel injection is the future (even for two-strokes, should KTM continue in its current direction), though to date, the carb has had it beaten on weight, simplicity, battery-less operation and reliability under extreme conditions.
Suzuki thinks it’s cracked it for MX, and has the courage to be the first on the block. It has a near unblemished record in its roadbike technology, so the experience is there.
We’ve had to wait though – like the first RMZ450, Suzuki was not releasing anything until it was utterly sure it had it right. Finally, Suzuki managed to airfreight two of them for me just before Christmas. Err, I mean press evaluation.
The place was Digger McEwen MX Park at Taupo, the day was fine and the assorted gentlemen of the press had Suzuki team riders Daryl Hurley and Paul Whibley along for the day, plus Hurley’s ‘07 title-winning RMZ for comparison.
RMZ EFI – the insides
In 2008, the carb is cart horse technology. Apart from the battery-less, injected Honda trial bikes and GasGas 450s (with battery), EFI is late in coming to MX, though it has been stalking offroad for a while disguised in Suzuki’s LT-R450 quad.
EFI offers perfect ‘jetting’, ultimate tuneability and better economy – all good for MX in theory (see sidebar). But does it work in practice?
Most of the tech is straight from Suzuki’s well-proven road bike EFI box of tricks, made simpler and more robust for offroad. There is no battery.
The system is powered by a high discharge, 18-pin magneto, which powers up the fuel pump and electrical system to drive the injector and brain. It also supplies feedback on crank position and speed, to optimise ignition and injection timing.
Sensors in the airbox monitor air density and temperature, and feed information to the ECU. Airflow itself is dictated by monkeys’ throttle hand, but is detected by the Throttle Position Sensor (TPS) that works with the air density information in the ECU to always deliver just the right amount of fuel. Altitude, hot, cold or muggy days, big handfuls or delicate throttle applications are effectively re-jetted, on a millisecond basis.
The fuel pump keeps the injector nozzle primed at 294kPa and returns any overpressure fuel to a bladder surrounding the pump. The bladder is there so if you tip it over there’s always fuel to suck until you pick the bike up.
The factory has seen fit to add a 10-second shutdown override to prevent major engine damage if it’s lying on its side revving its head off. Count out 10 seconds on your watch. It’s a while isn’t it? If you haven’t got back to your bike in that time, stalling is the least of your problems.
The throttle body is 43mm, which is large for a 450, but accounts for the restriction of the throttle butterfly. The throttle cable is connected to a progressive linkage, giving less movement at low throttle for more delicacy, and a quick open toward full throttle.
This is a good thing – EFI offers way cleaner jetting at low throttle openings than a carb ever can, and response can be a bit too bright. An example is the Aprilia RXV450 (yes, I know it’s a V-Twin).
On the ‘06 there was no throttle progression and it made life on slippery surfaces hell. The ‘07 had a progressive throttle and was a different bike.
You can take care of idle speed with the choke knob, which turns in or out – to adjust idle – as well as going up or down – when it’s cold.
2008 RMZ – the outsides
Everything has changed. Suzuki is very serious. The plastics are all new, with the back guard getting a touch less Buck Rogers looking, and the front a small dose of KTM styling. The blue seat and funky new two-tone side panels inject a fresh look to fairly conservative class, and the alloy tank is ice-cool.
I could go on about it all day. Topped off with wave discs and a new frame, the overall look, for a 450, is sparse and light.
The frame looks much like it could have come off a KX250-F and makes the 2007 look truck-like by comparison. It wears new Bridgestone M403/4s (tested on page 72).
Changes you can’t see are made to the shock and fork internals, swingarm wall thickness and gearbox, which at last is a five-speed. Slimline wideboy footpegs, throttle-side hot-start and o-ring chain complete the detailing.
It likes a kicking
In the morning you’ll need to boot it several times to get the electrics primed and ready to go. This seems an easy price to pay to avoid the extra kilos of a battery. Suzuki says the capacitor will run down to half charge in 30 minutes or fully discharge in about one and a half hours.
In my money, that means it will start like a normal bike in between races, but you’ll get some exercise after a long lunch. The decomp works well, as does the hotstart.
So, what was the power like?
Like a normal bike, just unbelievably smooth. The snap and bark of the delivery almost felt two-stroke-ish at times and there was never any hesitation or coughing.
The ability to compare directly against a carburetted bike – Daryl Hurley’s national title winning K7 “#1” – underlines how superior injection is. Hurley noted “it’s unbelievably crisp, and the consistency of the power is amazing.
It doesn’t bog off the big ski jump after the step up – even #1 has a minor hesitation on big flat landings like that.”
The delivery itself is solid in the low- to mid-range, and it revs out OK, but doesn’t produce much more power as you head to the top of the range.
This will be in part the effect of the 92dB silencer. Pros may want to swap that out, but I like it. There’s quite enough power to worry a muppet like myself, and it’s easy on the neighbours and easy on my ears. With soft, deep pumice and slippery spots, Taupo is never the best place to analyse power and I’m looking forward to heading to a grippier circuit to see what it truly does.
EFI is not totally immune to flame out. Admittedly, my cough and die test was in full goon mode – sitting near still in first gear, then twisting to full open. This is more about collapsing manifold pressure than anything to do with EFI though, and never occurred while riding like a normal human.
Riding it
After riding the ’08, ‘truck-like’ is the best way to describe the ’07. That’s not meant to be condemning, just the best way to illustrate the difference. The ’07, in my opinion, was still the best handling 450, it just required a quite deliberate guiding hand. The ‘08 doesn’t, and the words ‘gay abandon’ are possibly more appropriate.
The RMZ has lost a smidgen of front wheel plantedness and precision, in exchange for the general fling and chuckability. It’s a worthy trade-off and the 2008 RMZ450 is now a premier class bike that can be stuffed up the inside, gunned round the outside, or squared off at a moments notice.
The five-speed gearbox helps here, giving you the flexible choice of two gears for every situation where there used to be one.
Five speeds is how it should be for the majority of riders, though Hurley’s not a total fan yet. “The first thing I’ll spend time figuring out is the gears – after all the time on the four-speed, it’s taking me a while to know where to be.”
The RMZ felt stable in the sawdust section and hit ruts right on cue, but the track wasn’t that cut up either, so I’ll hold back from claiming class-winning handling just yet.
The clincher was the Digger McEwen centrepoint tabletop.
I’m not a jumper. In the course of racing I’ll try doubles and big tables, but mainly in a workmanlike, bum puckering way to just get the job over with. Centrepoint is big, but relatively easy. On #1 I just simply couldn’t get it right.
I was either in between gears, had my speed wrong and always flew like a piano. It was frustrating as much as frightening. On the ‘08 EFI however, I was starting to try out dangerous things.
It felt light, I was always at the right speed and it encouraged ME to experiment with beginner-school whippage. Prior, I would sooner have bet on Helen Clark eating a live rat on TV than that happening, but as God is my witness, it did. Hurley commented: “It was the first thing I noticed – it’s so easy in the air, the slim ergos let me do anything I wanted.”
Suspension broke in over the course of the day and felt better and better, though was never a patch on Hurley’s massaged #1. Even when smooth-ish as it was, Taupo’s a great suspension test and the RMZ always felt quite composed, but we’ll get back to you when we’ve had a longer ride.
Into the future
At first glance, Suzuki has produced a completely new v1.0 bike that works perfectly first time. This very rarely happens. Normally, there are glitches that don’t go away until v2.0 comes out.
There may yet prove to be, but we hope not. The 2008 RMZ450 EFI offers leading technology, amazing handling, good suspension and looks trick. While we think the top end power delivery could be better for pros, it will work well for the rest of the world.
It’s the first bike this year I badly want; the problem is, I’m going to have to wait. At this stage, April is the projected date, as Suzuki struggles to deliver them world-wide. In the meantime, we’re all going to have to scrap like dogs for the only two in the country.
Thanks to Simon Mead and the Suzuki Race Team for the bike and feedback.
