2008 Suzuki RM-Z450 Ride Impression Click the following link for a video with Suzuki's Kobi Iseri, and our tester-for-the-day, Michael Leib as they talk about the 2008 Suzuki RM-Z450.

Are you curious about the Electronic Fuel Injection on the new RM-Z450? You’re not the only one. We’d heard stories of Ricky Carmichael’s mechanic, Mike Gosselaar, digging into the bike earlier this year with T-handles flying, the moment it became available at a photo shoot. Of course, that was while it was still in pre-production stages, and following Ricky’s retirement, Mike has moved on to spin wrenches for Mike Alessi in the ’08 season, and the production version of the bike has finally arrived.

2008 Suzuki RM-Z450

New EFI? Check. Five-speed transmission? Check. Frame mods? Check. New plastic and styling? Check.

What did Mike find back then on his exploratory mission? The same thing that you’d find now. A small Keihin fuel injector body that replaces the normal carb arrangement, which makes for a very simplified look in the middle of the bike. It’s a system that self-adjusts for atmospheric changes like altitude and temperature. Maybe best of all, it’s reputed to make starting the bike easier, and provide excellent low-to-midrange throttle response, all while eliminating any hint of bogging problem.

That all sounds like some sort of dream state, right? Well, so far it appears that it not only works on theory, but in practical application as well. Suzuki has already had tons of experience with Electronic Fuel Injection, whether on the road side with their GSX-R sportbikes, or off-road, with the LT-R 450 Quadracer. But this is the first time production motocross bike that can claim the use of EFI.

According to Suzuki, the throttle body was specifically designed for the rigors of motocross, taking into account the wide extremes in riding conditions and bike posture. It also features a 12-hole fuel injector, and a progressive link for increased controllability right from when the throttle is first cracked open. Making bikes in the 450 class easier to ride and more controllable is the word of the day, and that’s an area where the EFI delivers.

Keihin throttle body

Here's the Keihin throttle body, which has been stripped down to show off the progressive link on the left side. That helps smooth the power as you roll it on.

The 16-bit ECU "brain" also tracks info like throttle position, intake pressure and air temperature as well as coolant temperature, and there’s even a tip-over sensor. Are the days of hop-ups coming in the form of a chip or a laptop-installed upgrade vs. the traditional pipe and silencer far off?

The EFI wasn’t the only change to the engine package this year. There were also changes to the top end of the engine, with mods to the port shape, valve angle and valve diameter, as well as combustion chamber shape, and bore and stroke. The use of EFI also allowed for a longer and straighter intake port. With an in-tank fuel pump as part of the EFI system, the fuel tank has been switched over from plastic to aluminum, and thanks to better fuel consumption than in the past, the size of the tank has actually been reduced.

A five-speed transmission also replaces the four-speed used in the past, making the bike more adaptable for a wider range of uses.

The engine and tranny weren’t the only areas to receive attention. The frame had some redistribution of material, reducing the size of the tank rails, as well as the body brackets (the vertical pieces behind the engine) to reduce stiffness, while increasing the size and thickness of the lower tubes (below the engine) to increase stiffness.


Michael Leib, on the 2008 Suzuki RM-Z450

Michael stretching his (and the RM-Z's) legs. Besides the power and benefits of the EFI, he was also impressed with the overall handling.

There are also a host of changes to the front and rear suspension units, the addition of wave-style rotors front and rear, slim and trim footpegs, a redesigned swingarm, textured top on the seat, and redesigned plastic throughout.

Of course, everyone wants to know how the bike rides, and it didn’t disappoint. The tester we brought out for the day was 120-pound Michael Leib, and while we were afraid that he might be the flag on the RM-Z450’s flagpole, he adapted quickly to the bike, made the necessary adjustments to his riding style (smooth low-RPM riding, vs. a wide-open beserko 250F approach), and every time he came in off the track, he had a big cheesy grin on his face. That was due both to the additional available power on tap, as well as the strong, smooth power right from idle, and the lack of coughs or bogs (though you still do get the occasional high-performance four-stroke pop and bang).

You can check the accompanying video (you’ll find the link at the top of the page), to get more comments from Michael, and to see the bike in action.

For now, Suzuki is the only player when it comes to EFI, and it looks like looks like mission accomplished in regards to bringing EFI to motocross. While Mike Alessi did debut the bike in the tight confines of the MGM Grand Garden Arena at the U.S. Open, we’ll be interested to watch the progress of the Rockstar Makita Suzuki squad in ’08 as they head to the bigger stadiums...and for high-altitude events like the outdoor National in Colorado to see if the EFI really shines. Will Suzuki be the only brand with an EFI bike in '09? And will we see it on 250Fs as well? That remains to be seen.

PhotoIf you want to talk about anything you've read, seen or watched in here, you can do it in the Vital MX Forums.

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