2011 SUZUKI RM-Z450 MOTOCROSS TEST: AFTER YEARS OF BEING DOWN, THE RM-Z450 IS UP

December 9, 2011
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Q: FIRST AND FOREMOST, IS THE 2011 RM-Z450 BETTER THAN THE 2010 RM-Z450?

A: Yes, but with so few 2010 RM-Z450s offered for sale last year, the important question is whether the 2011 RM-Z450 is better than the 2009 model?which it is by leaps and bounds.

Q: WHAT DID SUZUKI CHANGE ON THE 2011 RM-Z450?

A: The list of changes looks very small for 2011, but that is because Suzuki made some major mods in 2010. Here is the list of 2011 changes.

(1) Muffler. If you look inside the 2011 RM-Z450 muffler, you will see a reducer inserted inside the perf core. The 25mm reducer is the equivalent of downsizing the core diameter by 10mm (without making the end of the muffler look smaller). The length of the canister is the same as in 2010.

(2) Camshafts.
Both the intake and exhaust cams have new profiles.

(3) Compression ratio
. The compression has been bumped up from 12.2:1 to 12.5:1.

(4) Mapping. As you would expect on a fuel-injected bike, the ECU mapping was changed on both the fuel and ignition circuits to work with increased compression, new cam profiles and a revised muffler. There are three maps programmed into the ECU, and Suzuki provides the couplers to access them. The coupler only changes the fuel map, not the ignition (and except for cold winter conditions, we ran the “lean” coupler).

(5) Durability. The crankshaft has stronger bearings in the cases; the 43mm Keihin throttle body has more durable injectors, and the cylinder has an improved crankcase breathing channel.

(6) Brakes. The resin piston that was used in the 2010 front brake caliper has been replaced with an aluminum piston. Additionally, the cauliflower shape of the front rotor has been altered to lessen cracking and warping.

(7) Seat cover.
The gripper seat cover has been beefed up to last longer.


 
Q: WHAT CHANGES WERE MADE TO THE RM-Z450 IN 2010?

A: To understand the 2011 Suzuki RM-Z450, you have to go back one year to see the modifications that were made to the much-delayed and limited-release 2010 RM-Z450. Just 12 months ago, Suzuki put in a new cam chain tensioner, revised throttle body linkage, reverse 12-hole fuel injector nozzle (that directs the mist in the opposite direction), more efficient radiator louvers, new cam timing, a stronger connecting rod, 9mm-taller head tube, wider upper frame bridge, 0.5mm-thicker lower frame tubes, a more rigid swingarm and stiffer fork and shock springs.

2011 Suzuki RM-Z450: Since its inception, the RM-Z450 has been all about handling with minimal emphasis on power. No more! The 2011 Suzuki finally has an engine to complement the chassis.

Q: WHAT EFFECT DO ALL OF THESE CHANGES HAVE ON THE 2011 SUZUKI RM-Z450?
    
A: The original fuel-injected Suzuki RM-Z450 engine suffered from the same three issues that plagued most of the first generation of EFI bikes.
   (1) Flameout.
   (2)
Flat top-end power.
   (3)
Modest power output, albeit with very good low-to-mid throttle response.

Just two years ago, the 2009 RM-Z450 signed off very early. In the process, it only produced 50 horsepower (while KTM and Kawasaki were making two to three horses more). Additionally, the snappy and responsive low-end only gained power until it reached 8200 rpm?and then it went flat. It was a mediocre engine.

Which leads us to the changes that Suzuki made in 2010 and 2011. They reprogrammed the EFI and altered the cam timing to give the RM-Z450 more top-end power. And, when Suzuki installed the new 94 dB muffler, they upped the compression ratio to get back the low-end power that the muffler gave up.

 
Power: The 2011 RM-Z450 powerband benefits from the restrictive muffler, because it modulates the bottom end.


Q: DOES THE 2011 SUZUKI RM-Z450 ENGINE RUN BETTER THAN PREVIOUS RM-Z450s?

    
A: Yes. A big, bold and brash yes. This is a really good engine. It doesn’t have much personality or sparkle, but it is workman-like. The power delivery is deliberate; it lacks the irritating jolt of some fuel-injected bikes and the power rush of the KX450F and KTM 450SXF through the middle. Instead, it has a metered power that offers no unwanted drama (blame the choked up muffler).

Best of all, the power is exceptionally manageable off the bottom, builds steadily through the middle and, unlike the dead-on-top RM-Z450s of a few years ago, it pulls on top without a hint of signing off. Dare we say it? The 2011 RM-Z450 engine offers great breadth, infinitely usable power and no sudden surprises.

Q: HOW FAST IS THE 2011 RM-Z450?

A: Make no mistake about it?the 2011 RM-Z450 is fast. It is on equal footing with any bike on the track. Low-end power is very good, but its best trait is that it doesn’t exhibit any of the herky-jerky snatch that bothered 2009 CRF450 and 2010 YZ450F owners. It builds power smoothly and can hold its head high in the meat of the midrange. It may not have the most power from 7000 to 9000, but it’s only a smidge under the best dyno monsters. It is after 9000 rpm that the 2011 Suzuki RM-Z450 surprised the MXA wrecking crew the most. We fully expected to hit Suzuki’s infamous hard rev limit at ten grand and sink faster than the Titanic. Not so! It had KTM-style over-rev. That is a compliment.

The combination of a well-modulated low-end, climbing midrange and impressive over-rev gives the Suzuki RM-Z450 competitive power for the first time in a few years. It is a sleeper kind of power that doesn’t feel impressive by the seat of the pants, but the fence posts go by in such a blur that you know you are flying.

Q: HOW DOES THE 2011 RM-Z450 RUN ON THE DYNO?

A: After the first test rides, most of the MXA test crew was adamant that the Suzuki would have a great dyno curve. And they weren’t wrong. The 2011 RM-Z450’s peak power is 54.22 horsepower at 9000 rpm (that is four horsepower more than the 2009 model) and comparable to the KX450F’s 54.21 and KTM’s 53.92.

Q: IS THERE ANYTHING NOT TO LIKE ABOUT THE 2011 RM-Z450 ENGINE?

A: There is nothing to dislike in the power department, but there are three things that Suzuki needs to look into that are related to getting the power to the ground.
     

(1) Shifting.
The upshift from second to third was questionable (especially under a load). We never missed it on straights, flats or the exit of corners. Instead, we missed it on the backside of jumps, when cranked over in berms, and when the bike was wide open. The failure scenarios point to the fact that test riders missed shifts when they were rushed by circumstances?but motocross is all about being rushed to jam in a new gear. Some test riders thought that the propensity to miss upshifts was a deal breaker.

(2) Clutch.
It exhibits some eccentric sensations. When you start the bike, there is an odd whirring sound that is obviously emanating from the idler gearing dragging on something. The sound goes away when you rev the engine. Additionally, the clutch always feels like it is on the verge of slipping (even when the plates are brand new). We ran stiffer clutch springs (available from Barnett, Pro Circuit or Hinson) to ensure hook up.

(3) Overheating. Ride it hard on a hot day and it will not only puke water out of the overflow, but it will start banging and popping like there is a Jamaican steel drum band in the gas tank. We have learned through experience not to let the RM-Z450 run too long on the starting line, unless we want to be starting in a puddle. The stock 1.1 kpf radiator cap isn’t sufficient to prevent boiling?swap it out for a 1.4, 1.6 or even 1.8 (which is what comes stock on a KTM 450SXF).


All’s fair: The MXA test riders loved the cornering, powerband and sound reduction. They were lukewarm over the brakes and weight. Not a single test rider liked the erratic shifting, weak clutch or the overheating.


Q: HOW DOES THE 2011 RM-Z450 HANDLE?

A: Great. The 2011 Suzuki RM-Z450 is the best-cornering 450cc motocross bike on the track. It turns like a two-stroke. To get great cornering pro#wess, Suzuki has traded any illusion of all-around handling. Simply put, the Suzuki RM-Z450 is awesome in the corners and a little gruesome on rough straights. Even with the caveat that the RM-Z450 is skewed to one single aspect of handling, every MXA test rider loved the way the Suzuki handled. Yes, they all had “Juan Pablo Montoya moments,” where the front end would snap in the opposite direction so fast that they needed jazz hands to keep the bike straight. Strangely enough, however, most MXA test riders forgave the RM-Z450’s quirkiness in the rough in order to take advantage of its unequaled ability to crank an inside line, rail berms and turn on ice.

The Big Five bikes are divided into three groups?the good, the bad and the middle-of-the-road. We’d put Suzuki and KTM into the “good” category.

Q: IS THERE A TRICK TO MAKING THE MOST OF THE SUZUKI’S HANDLING?

A: Yes. The key to success with a Suzuki RM-Z450 is fork height. If you want it to turn sharper, slide the forks up in the triple clamps. The farther up you slide the fork legs, the steeper the head angle. Additionally, the less race sag you put into the rear shock, the steeper the head angle will become. Think about these two facts for a second. If you don’t think that the RM-Z450 turns sharply enough, set the race sag at 95mm and slide the forks up in the clamps. Then?hang on, because you will be dancing in the oversteer ballroom.

On the other hand, if you don’t like oversteer, you will want to slide the forks down in the clamps and set the race sage on 105mm to slacken the head angle.

As a rule of thumb, most MXA test riders set the rear sag at 100mm and then slide the forks up in the clamps until the bike oversteers. Once they have it on the verge of twitchiness, they slide the forks down 2mm. This system is foolproof.


 
 Boing: The Showa forks are still too soft.

Q: HOW IS THE SUSPENSION ON THE 2011 SUZUKI RM-Z450?

A: We’d like to say that it is excellent or very good?but we can’t. Prior to 2010, Suzuki’s suspension setup was finely tuned to suit the Lilliputian National motocross team. The springs were designed to support the weight of a New York fashion model on a steam diet. For 2010, Suzuki increased the spring rates?front and rear. This was a much needed move, but it was also a baby step. They still need to install stiffer fork springs, because the 2011 forks are better than they were two years ago, but not as good as they should be.

Our best advice is to go to stiffer fork springs. We changed the stock 0.48s to 0.49s (it should come as no surprise that 0.49s are what we have always recommended). One note: odd number spring rates are always available, so you may have to go to 0.50. Once you have the correct springs, you can raise and lower the oil height to meter the midstroke.

The shock is a little dead feeling, but on certain tracks that feel seems to work best. We had no issues with the shock spring rate and spent most of our time spinning the clickers.

Q: WHAT WAS OUR BEST FORK SETTING?
 
A: For hardcore racing, these are MXA‘s recommended 2011 Suzuki RM-Z450 fork settings:
   Spring rate:
0.49 kg/mm (0.48 stock)
   Oil height:
370 (377cc stock)
   Compression:
11 clicks out
   Rebound:
11 clicks out
   Fork leg height:
5mm up
   Notes:
The stock forks work fine on smooth tracks or for very light riders, but whether you stick with the stock springs or go stiffer?oil height is the key to success. We go stiffer on the spring and reduce the outer tube oil height.

Q: WHAT WAS OUR BEST SHOCK SETTING?
    
A: We weren’t wowed by the rear suspension, but we weren’t cowed by it, either. We could live with this setup.
For hardcore racing, these are MXA‘s recommended 2011 Suzuki RM-Z450 shock settings:
   Spring rate:
5.8 kg/mm
   Race sag:
100mm
   Hi-compression:
2 turns out
   Lo-compression:
14 clicks
   Rebound:
10 clicks
   Note:
Until you get the front end to stay higher in its stroke (with stiffer fork springs), the rear will jackhammer around. You want to seek a balance between the front and rear; in stock trim, it is out of balance.

Q: WHAT IS THE SUGGESTED RETAIL PRICE?

A: The manufacturer’s suggested retail price (MSRP) is $8149, which is identical to the Kawasaki KX450F’s price tag.

Q: WHAT DID WE HATE?

A: The hate list:

(1) Shifting. If you rushed a shift, you could end up in neutral, and on more than one occasion we shifted up only to discover that we were still in the same gear.      

(2) Muffler design. The muffler melted through the right side panel.

(3) Rear brake adjustment. Suzuki’s rear pedal adjustment has a very narrow window. If you miss it, the rear brake will burn up. Here’s the caveat: there must be free play inside the master cylinder’s slotted clevis.

(4) Bolts. Suzuki’s bolt heads are made of butter. They were easy to round off with a T-handle.

(5) Clutch. If you use it hard early in a moto, you won’t have to worry about using it later. The MXA test crew is critical of the RM-Z450’s overall reliability on the whole (it is hard to forget how quickly and easily we broke the 2008 RM-Z450?stopping its production in its tracks).

(6) Weight. This is a very heavy bike, and even though the sensation of weight disappears at speed, it returns when you try to put the bike up on its stand.

(7) Overheating. If we were you, we would invest in a higher pressure radiator cap and CV4 space blanket for the bottom of the gas tank.

(8) Throttle grip.
If you want to install aftermarket grips on the RM-Z450 throttle tube, lots of luck. The grips are vulcanized onto the throttle tube.


In the air the porcine nature of the Suzuki RM-Z450 disappears.

Q: WHAT DID WE LIKE?
 
A: The like list:

(1) Starting. No hassles. It typically takes three kicks, but the higher you lift your leg, the more likely the bike is to fire up sooner.   

(2) Handlebars.
Renthal FatBars are above reproach.

(3) Handling.
It is razor sharp. It won’t be everybody’s cup of tea, but it’s different from every other 450 four-stroke. The idea that all motocross bikes are the same is blown out of the water when it comes to handling. The RM-Z450 is spectacular in the corners.

(4) Sound. The 2011 Suzuki RM-Z450 easily passed the AMA’s 94 dB sound limit at 91.2 dB. It did, however, fail the FIM’s 115 dB two-meter-max test when it blew a 117.

(5) Reprogram. The 2011 RM-Z450 comes with two couplers that will change the fuel mapping. We prefer the “lean” coupler and ran it all the time. You might need the rich attachment in the dead of winter.

(6) Powerband. This isn’t a powerband that you get all misty over; it isn’t a beautiful woman with a come-hither smile. Nope, it is a sturdy and reliable workhorse that gets the job done without fluttering its eyelashes.

Q: WHAT DO WE REALLY THINK?

A: This isn’t your father’s Suzuki RM-Z450. The old-school RM-Z450 was undersprung, flat on top and signed off like it was falling off a cliff. Not anymore. The 2011 Suzuki is stiffer, has plentiful top-end power, and doesn’t sign-off until you get your money’s worth. We like it?but we plan our shifts well in advance.

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