MXA’S 2012 SUZUKI RM-Z450 MOTOCROSS TEST: IT MAY BE REHEATED 2011 LEFT-OVERS, BUT IT IS REHEATED FILET MIGNON

December 19, 2011
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Q: FIRST AND FOREMOST, IS THE 2012 SUZUKI RM-Z450 BETTER THAN THE 2011 RM-Z450?

A: Not unless the red stripe down the seat cover has some technical edge that we are unaware of.

Q: WHAT DID SUZUKI CHANGE ON THE 2012 RM-Z450?

A: When we tell you Suzuki changed nothing?save for the BNG, seat cover, fuel-pump cover and engine breather hose?you will probably think less of the 2012 RM-Z450. You shouldn’t. Why not? Over the past two years (2010 and 2011), Suzuki made 18 significant changes to the RM-Z450. The changes encompassed everything from the muffler to the cams, to the compression ratio, to the ECU mapping, to the throttle body linkage, to the 9mm-taller head tube, to the stiffer fork and shock springs.



Q: WHY IS MXA SO FORGIVING OF SUZUKI’S LACK OF 2012 UPDATES?

A: Simple Simon. The 2011 Suzuki RM-Z450 was a terrific bike. In fact, it and the KTM 450SXF were so far ahead of their competition last year that either one of them could be forgiven for believing that they could rest on their laurels.

2012 Suzuki RM-Z450: If you loved the 2011 Suzuki RM-Z450 then you are going to like the 2012 version. Save for a red stripe on the seat cover, the two bikes are identical in performance and hardware.



Sleeper: The RM-Z450 engine is close to the perfect balance of manageability and power. It isn’t scary fast or deadly slow?it is instead a very effective racing powerplant.

 


Q: WHAT WOULD MXA HAVE LIKED SUZUKI TO FIX FOR 2012?

A: We accept that in these hard economic times, sometimes it is smarter for a manufacturer to tread water. Because making major changes, especially if those changes don’t work, could sink the company.  Still, as much as we liked the 2011 Suzuki RM-Z450, we didn’t like everything about it. It is inherent in motorcycle test riders to find problems, point them out, and then wait for the manufacturers to fix them. By backstroking into 2012, Suzuki didn’t fix the most blatant flaws.

If the MXA wrecking crew had its druthers, we would have made these four changes for 2012:

(1) Shifting. The gearbox needs work?especially on the upshift from second to third under load. Whenever a test rider was rushed to make shifts, forced to shift in the air or jamming it into gear in the middle of a berm, the gearbox’s refusal to upshift was a deal-breaker.

(2) Clutch. At this point, we have to give credit to KTM. Although they could have stood pat with the 2012 KTM 450SXF, they designed, engineered and produced the most creative clutch ever put in a showroom-stock racing bike. KTM didn’t have to, but they did. Suzuki, on the other hand, really needs to work on their clutch. It makes weird whirring noises (like the idler gear is dragging on something), and the RM-Z450 clutch is always on the verge of slipping. We had to resort to stiffer clutch springs to keep the pack together.

(3) Overheating
. The stock 1.1 kpf radiator cap isn’t sufficient to prevent boiling. If you ride this bike hard on a hot day, it will puke water out of the overflow. Worse yet, unless you like starting in a puddle, don’t let the RM-Z450 idle on the starting line for very long. We installed a high-pressure 2.0 kpf radiator cap from CV4 to raise the boiling point.

(4) Rear brake adjustment. Suzuki’s rear pedal adjustment has a very narrow window. If you miss it, the rear brake will burn up. Caveat: There must be freeplay inside the master cylinder’s slotted clevis.

Q: HOW DOES THE 2012 SUZUKI RM-Z450 ENGINE RUN?

A: The RM-Z450 has a really good engine. It’s not vivacious, but it is deliberate. It’s not aggressive, but instead has a metered powerband that gets the job done without any fanfare. It is workmanlike.

The best trait of the 2012 (and, by proxy, the 2011) RM-Z450 engine is its powerband. It is very manageable off the bottom, builds steadily through the middle and, unlike the dead-on-top RM-Z450s of a few years ago, it pulls across the top without a hint of signing off. You gotta like a powerband that works without drama, has infinitely usable power and doesn’t deliver any herky-jerky surprises.

Q: HOW WELL DOES THE 2012 SUZUKI RM-Z450 RUN ON THE DYNO?

A: The 2012 Suzuki RM-Z450 doesn’t have to hang its head when it comes to dyno time. It produces 54.08 horsepower at peak. That isn’t as much as the 55.50-horsepower 2012 KX450F, but it is considerably more than the 52.59 ponies of the 2012 CRF450.

Roll-on power is very good, and there is none of the abrupt chain snatch that bothered many racers on the first generation of fuel-injected bikes. The low end is nice, but where the RM-Z450 really begins to shine is across the midrange and into the top end. Unlike pre-2011 Suzukis, the 2012 RM-Z450 doesn’t go flat on top. It pulls with a sleeper-style of power that is massively manageable by riders, from Pro to Novice.


 
Source: Most of Suzuki’s cornering prowess comes from their steep head angle and well chosen offset. Word of warning?upgrade the radiator cap if you don’t like steam.

Q: HOW DOES THE 2012 RM-Z450 HANDLE?

A: No one will contradict this statement: the Suzuki RM-Z450 is the best-turning 450cc motocross bike ever made. Most MXA test riders swear that the RM-Z450 feels more like a two-stroke than a four-stroke in the tight-and-twisties. It makes swift direction changes, as though the front end were attached to a roller-coaster track. It is thrilling to dive inside of every bike on the track?and know that the other riders can’t do anything to stop you (unless they are on Suzukis also).

Suzuki deserves credit for building a bike that can turn like a wizard. The downside is that the steep head angle, short trail and forward-weight bias turn it into a witch on fast, rough and loose straights. You give to get?and Suzuki gave up straight-line stability for accurate steering at lower speeds.

Q: HOW IS THE SUSPENSION ON THE 2012 RM-Z450?

A: Our best advice for Suzuki RM-Z450 owners (of every model year) is to go stiffer on the fork springs. We traded the stock 0.48 kg/mm fork springs for stiffer 0.49 kg/mm springs. 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 WERE OUR BEST FORK SETTINGS?
 
A: For hardcore racing, these are MXA‘s recommended 2012 Suzuki RM-Z450 fork settings:
   Spring rate:
0.49 kg/mm (0.48 stock)
   Oil height:
370cc (377cc stock)
   Compression:
11 clicks out
   Rebound:
11 clicks out
   Fork leg height:
5mm up
   Notes:
If you are light, slow or race on smooth tracks, the stock forks will be okay. But for anyone fast, heavy or headed across rough ground, go stiffer. We go stiffer on the spring and reduce the outer-tube oil height by 10cc.

Q: WHAT WAS OUR BEST SHOCK SETTING?

A: For hardcore racing, these are MXA‘s recommended 2012 Suzuki RM-Z450 shock settings:
   Spring rate:
5.8 kg/mm
   Race sag:
100mm
   Hi-compression:
2 turns out
   Lo-compression:
14 clicks out
   Rebound:
10 clicks out
   Notes:
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. You won’t get the shock to work until you get the forks to handle their fair share of the load.

Q: WHAT DOES THE 2012 SUZUKI RM-Z450 WEIGH?

A: At 244 pounds, the RM-Z450 is 13 pounds heavier than the CRF450, six pounds heavier than the YZ450F, two pounds heavier than the KX450F and one pound heavier than the KTM 450SXF (and the KTM has an electric starter).

Q: IS THE IGNITION PROGRAMMABLE?
 

 
Side effect: One of the benefits of not changing the forks, shock or linkage is that a record of past fixes can be applied to bring the suspension settings up to snuff very quickly.

A: Suzuki is a little behind the times when it comes to providing reprogramming software for the RM-Z450 (relying instead on Yoshimura’s tuning tools). Suzuki does, however, offer three plug-in ECU couplers (similar to the Kawasaki KX450F couplers?only Suzuki had them first).

The three plug-ins are lean (white), stock and rich (gray). In our opinion, you can throw the gray coupler in your toolbox and forget it until you go riding on a 40-degree day in Upper Michigan. As a rule of thumb, every MXA test rider preferred the lean (white) coupler. It was noticeably snappier and more responsive.

Q: WHAT DID WE HATE?

A: The hate list:

(1) Shifting. Occasionally, we would shift up only to discover that we were still in the same gear.

(2) Bolts. Always turn a Suzuki bolt counterclockwise before turning it clockwise.

(3) Clutch. If you use it hard early in the moto, you won’t have to worry about using it late in the moto.

(4) Weight. The sensation of weight disappears at speed, but it returns when you try to put the bike up on its stand. This is the heaviest motocross bike made.

(5) Overheating.
This is the worst cooling system on any motocross bike. It should be called a heating system.

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

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

(1) Handling. It is razor-sharp at low speeds and slit-your-wrist busy at high speeds, which is why desert racers don’t ride Suzukis.

(2) Powerband.
Very professional. Very broad. Very easy to use. Very good.


Old saw: Once in motion the weight of the RM-Z450 is less objectionable than when the bike is being hoisted up on a bike stand. You can blame EFI for the extra weight of modern bikes.

Q: WHAT DO WE REALLY THINK?

A: In last year’s MXA 450 shootout, the 2011 Suzuki RM-Z450 finished a very close second to the 2011 KTM 450SXF. Standing pat with the cards they played in 2011 means that the Suzuki RM-Z450 isn’t going to move up in the rankings?and, given the improvements to their biggest competitors (KTM and Kawasaki), they are destined to slip back a place or two. Don’t let that deter you; the 2012 Suzuki RM-Z450 offers the kind of handling prowess that you can’t get anywhere else?and that just might trump bikes with full houses.

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