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2015 Suzuki RM-Z450 First Ride

Wednesday, August 13, 2014


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2015 Suzuki RM-Z450 First Ride Video
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Suzuki chooses to refine instead of totally revamp its RM-Z450 motocrosser. Watch the 2015 Suzuki RM-Z450 First Ride Video to see if they made the right move.
In motocross, confidence is everything. So instead of a risky full redesign, Suzuki chose to hone its trusty RM-Z450 motocrosser ($8749). Since it debuted eight years ago, the fuel-injected RM-Z has received a steady stream of updates in an effort to extract the most performance from its battle-tested platform. For 2015 the RM-Z450 gets a new frame and works-style Triple Air Chamber (TAC) fork (see sidebar) from Showa.

Even though its fuel-injected, getting the yellow bike’s water-cooled Single fired to life hasn’t been the easiest, requiring a deliberate and well-timed kick to get it lit on the first try. So engineers went back to the drafting board in Japan to improve the starting procedure. An inch-longer kickstarter lever was fitted and matched to revised gears, exhaust camshaft and decompression mechanism. This enabled the deletion of the manual and thumb actuated hot-start lever.

“The ’14 model was a bit hard to start,” remembers MotoUSA RM-Z test rider, and three-time X-Games gold medalist, Vicki Golden. “The ’15 model, I’ve watched people start it with their hand which is pretty insane for a 450.”




(Top) Not only is the kickstarter more than an inch longer, some of the engine’s internals have been re-worked to make it easier to start, hot or cold. (Center) The SFF-AIR front suspension separates air spring duties (right leg) with an inner, outer air chamber (pictured), and balance chamber. A conventional damping cartridge inside the left leg. (Bottom) Look carefully and you’ll see that the frame’s downtubes have less material for added chassis flex.
The RM-Z still offers the ability to tune the engine’s powerband with simple and easy-to-use plastic couplers. In the standard setting throttle response is precise, doling out a thick and immediate spread of power at all revs. While Vicki prefers the standard setting, if seeking extra engine ‘oomph in loamy terrain or deep sand choose the ‘white’ coupler, or vice-versa, for more mild response on hard-pack terrain install the ‘grey’ coupler.

“I did notice that the bike was quieter,” says Vicki. “The bike sounded quieter [so] you’d think it would be slower, but it was actually fine power-wise. It felt all the same as last year’s bike.” 

Vicki did file one complaint though, saying that she’d go larger on the rear sprocket if it was her bike. However the rest of the powertrain, including the five-speed gearbox and cable-triggered clutch, all performed as advertised. We were especially keen on the transmission’s secure engagement between cogs, which helps eliminate mis-shifts. As Golden mentions, the muffler was re-worked in order to make it quieter for riding in noise-sensitive areas.

Any racer will tell you that a good start is one of the keys to winning a race. Accordingly, Suzuki has fitted its newly developed electronic Holeshot Assist Control. The rider can choose between one of two modes (as well as ‘off’) via a small clear button next to the engine kill switch: ‘A’ mode (slowly flashing indicator light) is designed for use on slippery surfaces and/or concrete starts. It retards engine timing for 1.2 seconds after launching or until the motorcycle is shifted into third gear, whatever happens first. ‘B’ mode (indicator light rapidly blinking) is for more explosive power on high grip terrain. It returns to standard ignition timing 4.5 seconds after launching or upon shifting into fourth gear.

“B-mode here was almost too aggressive,” thinks the Moto X gold medalist. “With a holeshot device though that thing would be a game changer. It would be hard to say if I would use it. X-Games normally is more slippery. But it would be a good feature to have—to be able to try both and see which one would work better. Either mode would be better than not having it.”

While we like the RM-Z’s motor package, the evolution of its chassis is what really
RM-Z450 Suspension Settings
Fork
Inner Chamber: 175 psi
Outer Chamber: 0 psi
Balance Chamber: 175 psi
Compression: 8 (Turns out)
Rebound: 13
Shock
Sag: 105mm
Low-Speed Compression: 12
High-Speed Compression: 2
Rebound: 12
stands out. Where the ’13 and ’14 had a rigid feel with a single-sided coil spring fork that was tricky to set-up, Suzuki’s latest chassis is far more compliant. To do this, the frame down tubes (cradle area just forward of the engine) have less material (Suzuki claims a 4% weight reduction) and the inner ribbing on each spar (area behind engine where the swingarm links) were modified for more flex. New rear axle blocks offer another slight rigidity tweak. Complementing this is an all-new air fork from Showa that is virtually identical in design to the works kit used on the Yoshimura and RCH racebikes (aside from ultra-slippery coatings and oil).



(Left) Perhaps the greatest attribute of the ’15 RM-Z is the added confidence it gives its rider as three-time X-Games gold medalist, Vicki Golden demonstrates.(Center) With the release of the Single Function Fork Triple Air Chamber (SFF-TAC), Shows joins its arch rival Kayaba in the air suspension game. But contrary KYB’s single chamber set-up, the Showa unit incorporates a triple air cavity design. (Right) The Suzuki’s engine blends the best of both worlds: Not only is it smooth and tractable, it’s got plenty of snap throughout the rev range.


“I’m more of a rider that prefers a plusher set-up,” says the 150-pound Golden, who represents the lighter side of rider spectrum on a 450. “This bike is night and day different compared to the ’14 model. The ’14 model was on the rigid side. With their new frame and the suspension—the whole set-up is just so much better. The bike is stupid good at cornering. I feel like you could probably ghost ride that thing into a rut and you’d be fine. It corners on its own.”

“It’s so much better than the single-sided [coil spring] forks,” she adds. “It just works way better and makes the bike corner a whole lot better. Even the smaller bumps—it felt like you couldn’t even feel the bumps that were there. The bigger bumps were a little bit more rigid on initial impact but once you got past the rest of the stroke it was a lot better.”



(Top) Although it only lost two pounds on the scales, with the addition of the SFF-AIR front suspension and updated frame, the RM-Z450 feels lighter and more nimble than before. (Center) Even though it doesn’t offer the same level of control adjustment we appreciate the RM-Z’s purposeful and well throughout ergonomics. (Bottom) Greater adjustability and almost infinite fine tuning are benefits of Showa’s TAC fork. However it could also be easier to get ‘lost’ in set-up.

The RM-Z’s extreme agility has always come with a price: stability. However our lady tester claims the chassis enhancements have also improved overall stability: “I noticed last year’s model was a little bit scary in the high-speed stuff. But this year’s model, high-speed, low-speed, tight, technical, it all works so much better.”

Although it lacks a degree of handlebar and footpeg adjustability as offered on other brands, it never bothered us. And aside from selecting a different bar bend we’re happy with the yellow bike’s cockpit as it’s an effective platform to work from.

Braking power from the wave-style disc brakes is adequate, but a little extra feel and friction force could is an area where Suzuki could stand to make some improvements. Although they are getting a little dated, we still love the versatile and surefooted grip from Bridgestone’s trusty M403/M404 intermediate terrain tire combo.

From the outside it may appear the same, but make no mistake: Suzuki’s latest iteration of the RM-Z450 is a considerably improved track weapon. Though it cut just two pounds from the previous model (247-pound claimed curb weight) with the chassis’ improved rigidity and the front suspension’s enhanced action, the yellow bike is more cat-like, allowing the rider to put in fast laps with greater confidence.

Suzuki RM-Z450 Highs & Lows
Highs
  • Wide and very precise range of fork adjustment
  • Incredible handling
  • Smooth, highly useable powerband
Lows
  • Purchase price doesn’t include fork air pump
  • TAC fork can require more set-up time
  • Brakes could offer improved feel and power


















2015 Suzuki RM-Z450 First Ride


Backgrounds are the first thing we fit on our bikes. This time we sourced a setup from Split Designs   39.99 . We are impressed by the precise fit and ease of application. 2015 Suzuki RM-Z450   8749. Housed inside a larger 49mm diameter leg  right  are a trio of separate chambers. The primary inner chamber acts as a main spring and is inflated based on rider weight and or skill. The balance chamber  located at the bottom of the leg  acts as a negative force  counteracting the pneumatic spring. Think of it as preload on a standard metal spring with the two forces opposing one another. Adding pressure to the balance chamber sucks the suspension down and allows the rider to tune initial action as the fork moves within its stroke.






2015 Suzuki RM-Z450 Photos
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Inside Showa's TAC Fork
 


With the release of the Single Function Fork Triple Air Chamber (SFF-TAC), Shows joins its arch rival Kayaba in the air suspension game. But contrary KYB’s single chamber set-up, the Showa unit incorporates a triple air cavity design.

Housed inside a larger 49mm diameter leg (right) are a trio of separate chambers. The primary inner chamber acts as a main spring and is inflated based on rider weight and/or skill. The balance chamber (located at the bottom of the leg) acts as a negative force, counteracting the pneumatic spring. Think of it as preload on a standard metal spring with the two forces opposing one another. Adding pressure to the balance chamber sucks the suspension down and allows the rider to tune initial action as the fork moves within its stroke.

The third outer chamber operates at low pressure and is used to fine-tune bottoming resistance against big impacts. Each chamber has a Schrader valve and is filled with a mountain bike-style air pump (not included, but available as a $74.95 accessory). Using compressed air is not recommended due to the threat of moisture contaminating the system.

The left leg houses the damping cartridge and offers compression (atop the cap) and rebound (underneath leg) adjustability.

Advantages of the TAC fork are not only diminished weight, but reduced sprung weight, much wider yet more precise range of adjustability, and redundancy in the event of mechanical failure. Possible disadvantages include having more items to check/adjust before your moto and the ability to get ‘lost’ in terms of suspension set-up, air pressure, etc.
 
What the Pros Say:
 


James Stewart, No. 7, Yoshimura Suzuki:


This is the first stock bike I’ve ridden since 2012. It’s actually pretty good. It’s nice to see all the changes Suzuki has made toward the racebike. When I hopped off my bike [Yoshimura factory RM-Z], besides the handlebar, it’s not too much different. That’s what we [his team] were already talking about. I still think the Suzuki is a really solid motorcycle overall. It’s great in a lot of different areas. It turns well and is a motorcycle that works for all skill levels, ranging from myself to the regular average Joe. We’ve been running the triple [TAC] for about a year and a half now. I like it. It gives the tuner and rider more set-up options in a much shorter amount of time. Before you had to go to someone to get it done, so it’s a lot easier. And when you’re spending nine, or 10 grand on a motorcycle, you don’t want to spend another grand on getting your suspension dialed.

Weston Peick, No. 40, RCH Racing Soaring Eagle:

Our factory bike uses the Triple Air Chamber fork. It’s pretty much the exact same fork as the 2015 production fork, besides the internal coatings. It feels different [compared to a conventional coil spring unit]. It gives the front end a better feel for the track, its lighter, and it helps the motorcycle feel more nimble. You can turn the bike a lot easier and put it where you want to go. It’s an all-around better, more progressive-feeling fork. Everything just falls into place better with it.
 
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2015 Suzuki RM-Z450 Tech Specs
 


Engine:
449cc, four-stroke, liquid-cooled, Single cylinder, DOHC
Bore x Stroke: 96.0mm x 62.1mm
Compression Ratio: 12.5:1
Fuel Delivery: Fuel-injection
Clutch: Wet multi-plate, cable actuation
Transmission: Five-speed, 13/50 gearing 
Front Suspension: Showa Seperate Function (SFF-TAC); Nine-position compression and 12-position rebound damping adjustment; 12.2 in. travel
Rear Suspension: Showa gas-charged, 12-position compression, step-less high-speed and 12-position rebound damping adjustment
Front Brake: 240mm disc, double-piston caliper
Rear Brake: 240mm disc, single-piston caliper
Handlebar: Renthal Fatbar
Tires: Bridgestone 80/100-21 M403, 110/90-19 M404
Weight: 247 lbs.
Wheelbase: 58.9 in.
Length: 86.2 in.
Width: 32.7 in.
Ground Clearance: 12.8 in.
Seat Height: 37.6 in.
Fuel Capacity: 1.6 gal.
MSRP: $8,749
 
 
 

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