2018 Suzuki RMX450Z Review | Dirt Rider
Jeff Allen

2018 Suzuki RMX450Z Review

Full test of Hamamatsu’s 450 off-road trailbike

After a seven-year absence from the off-road market since it was unveiled back in 2010, Suzuki brought the RMX450Z back to the market last year and it’s now is in its second year of production since its reintroduction. There are no mechanical changes to the 2018 bike, only “bold new graphics” with blue accents on the radiator shrouds and seat cover. There are also some technical changes in the bike’s green sticker eligibility.

2018 Suzuki RMX450Z

The Suzuki RMX450Z has a few appearance differences for 2018 with blue accents on the radiator shrouds and seat cover.

Jeff Allen

In California, a green sticker is issued to off highway vehicles (OHV) that meet the emission standards established by the California Air Resources Board (CARB) and can be ridden year-round. For 2018, models are required to have an evaporative emission recovery system on the fuel tank, which the yellow machine does not have, so the 2018 RMX450Z is only red sticker eligible. Red stickers are alloted to OHVs that don’t meet emission standards and can be ridden in California OHV riding areas only during certain times of the year designated on the California State Parks Off-Highway Motor Vehicle Recreation website..

RMX450Z include an 18-inch rear wheel

Off-road-specific components that come stock on the RMX450Z include an 18-inch rear wheel, kickstand, skid plate, headlight, LED taillight, and dual mode (Sport/Standard) instrument cluster.

Jeff Allen

The good news is the RMX450Z is equipped with a spark arrestor in stock form, is sound-level legal, and red sticker eligible. The RMX450Z is a trailbike; Suzuki did not build it to be a closed-course off-road competition bike, at least not in stock trim. The RMX450Z comes with several off-road components right off the showroom floor, including an 18-inch rear wheel, kickstand, skid plate, headlight, LED taillight, and a dual mode (Sport/Standard) instrument cluster. Unlike most off-road bikes that are usually spec’d with Dunlop AT81 tires, the RMX450Z comes with a Dunlop D742FA front tire and Dunlop D756 rear tire. Suzuki offers a six-month unlimited-mileage limited warranty on the RMX450Z, which can be lengthened via the Suzuki Extended Protection program (SEP) as well.

2018 suzuki RMX450Z muffler

Suzuki’s off-roader is equipped with a spark arrestor in stock trim and is sound-level legal.

Jeff Allen

Engine

The RMX450Z engine looks fairly similar to the powerplant of the RM-Z450 motocross bike, but it behaves much differently on the trail and has a few notably different components. It has an electric starter with a kickstart backup, a modified inlet tract and revised cam profiles to increase low-rpm and midrange power, a larger magneto-generator to charge the battery and power the lights, a hinged lid on the airbox for quick air filter maintenance and better protection from debris, and a coolant reservoir tank. Lastly, the five-speed transmission has wide gear ratios and primary/final drive ratios to better suit various off-road riding situations.

The RMX450Z comes stock with a throttle stop that only allows it to be opened a fraction of the way from wide open to help the bike meet sound-level regulations. However, because we intended to only ride the bike in closed-course conditions, we removed it. Taking off the throttle stop took about 10 minutes and involved removing a bolt from the throttle body. Once removed, we installed a shorter bolt (that wouldn’t restrict the throttle opening) to cover up where the throttle stop bolt was.

2018 suzuki RMX450Z incline

The RMX450Z engine is very smooth and predictable, which helps make it easy to manage in tighter, more technical situations.

Jeff Allen

Two other items that help make the bike red sticker and sound-level legal are the spark arrestor and sound reducer in the muffler. While one or both of these items may inhibit the bike’s overall engine performance, we opted to leave them in because, in stock form, the EFI system cannot adjust for removing them and the engine could sustain damage as a result of the lean running conditions if one or both of them were to be taken out.

On the trail, the RMX450Z engine is very smooth and predictable. It has more of a classic four-stroke feel that is accentuated with the restricted muffler and airbox. The motor has a mild amount of engine-braking and no distinct hit in the powerband, which helps make it easy to ride hard or in a more conservative manner. The rider-friendly powerband makes it easy to manage in tighter, more technical conditions, and is also easy to ride hard on higher-speed sections of the trail.

2018 suzuki RMX450Z wheelie

First gear handles even the slowest of sections with ease while second gear is best used on trails that are still technical but not quite stop-and-go speeds.

Jeff Allen

First gear handles even the slowest of sections with ease while second gear is best used on trails that are still technical but not quite stop-and-go speeds. In these tighter sections of the trail, it became evident the clutch pull is on the stiff side and tends to fade under mild abuse, but that was the only thing we would like to improve in the bike’s ability to handle the slower-going areas as it performed great otherwise. Third gear on the RMX450Z handled most other areas of the trail very well, and we rarely used fourth of fifth gear except on wide-open, flat terrain. The 1.6-gallon gas tank holds enough fuel for approximately 35 miles of trail riding, so if you plan to ride longer than that, bringing extra fuel might be necessary, and if you regularly ride longer than that, investing in a larger-capacity gas tank might be a good option.

Showa 47mm fork and Showa piggyback-reservoir-style shock

The Showa 47mm fork and Showa piggyback-reservoir-style shock are set up more on the soft side for off-road, but have more of a performance-based feel to them that match well with the chassis characteristics.

Jeff Allen

Suspension

A Showa 47mm fork and Showa piggyback-reservoir-style shock grace the RMX450Z. Both units are set up more on the soft side for off-road but had more of a performance-based feel to them that match well with the chassis’ characteristics. The fork soaked up small impacts to the front wheel such as rocks, logs, and bumps very well and didn’t have the tendency to step out from underneath itself. Likewise, the shock absorbed impacts well and helped the rear of the bike maintain traction when riding over obstacles. Similar to most off-road bike’s stock suspension, and the trade-off for a softer setup in general, the fork and shock tended to bottom out in the case of a sudden impact when hitting a G-out or mistiming a whoop-style section, but that’s a trade-off for how well the Showa units absorbed the small obstacles.

2018 suzuki RMX450Z charging

The RMX450Z is very stable at speed.

Jeff Allen

Chassis/Handling

Handling is an area that Suzuki motocross bikes are known to succeed in, and the same can be said about the RMX450Z. Similar to the RM-Z450 motocrosser, the RMX has more of a rigid chassis and turns exceptionally. The bike’s excellent cornering prowess is even more impressive with how well the bike tracks in a straight line. We’d like to have a little more stopping power from the front brake, but that’s largely due to the 250mm rotor and can be easily improved with a larger-diameter disc. The RMX450Z’s ergonomics are very comfortable and easy to get used to. The radiator shrouds are thin and the levers have an agreeable bend. The Renthal Fatbar has a neutral bend but seems a little high due to the seat height being a little less than the motocross bike. Lastly, the Dunlop D742FA front and Dunlop D756 rear work great and hook up well in a variety of conditions.

2019 Suzuki RMX450Z sliding

Suzukis are well known for their incredible cornering capabilities, and the RMX450Z lives up to that reputation.

Jeff Allen

Conclusion

The Suzuki RMX450Z is a well-rounded trailbike. It has a rider-friendly engine mellow enough to not be a handful in tight areas and is easy to ride aggressively in wide-open areas. The Showa suspension components are right on the mark for what the bike is intended for, and the chassis offers excellent cornering ability coupled with impressive straight-line stability. The ergonomics are easy to get used to with the bike’s slim bodywork, relatively low seat height, and Renthal Fatbar. The RMX450Z does what it is intended to do very well and is a fun trailbike.

Suzuki RMX450Z

The Suzuki RMX450Z is a well-rounded trailbike that’s fun to ride.

Jeff Allen

Second Opinion

Allan Brown
Age: 47, 5’10”, 175 lb., Off-Road Intermediate

My expectations for the 2018 Suzuki RMX450Z were not very high. I didn’t have any previous experience with this model and the specs did not make it look very promising. This bike is a touch heavy and down on power because of a muffler that was designed to be green sticker compliant. As we discussed, while the 2017 model was green sticker eligible, this 2018 model is no longer green sticker compliant. We went out to my regular off-road riding area where I’m familiar with the terrain to get a good feel for the bike. Normally, we ride a minimum of a 40-mile loop and one of my first concerns was the RMX’s rather small gas tank for an off-road bike. I made sure to fill it to the top and carried additional gas in my pack.

The bike comes equipped with a Dunlop 742FA front tire and a 756 18-inch rear tire. For me, these are excellent tire choices and I prefer them over the AT81 rubbers that come standard on most other off-road models. They might not last quite as long as the AT81s, but they do offer better performance and a more predictable feel. We rode in rocky desert conditions, and after my two days of 75 miles and the 25 miles that were on the bike before I rode it, the tires are beginning to show some significant wear. If we continued to ride in the same conditions, I’d estimate it will be time for new tires at the 200-mile mark. While setting the sag, I noticed the overall seat height seemed a touch lower than the RM-Z450 motocross bike. On this RMX, I was able to have both feet flat on the ground. However, when sitting on the bike, the bars felt a touch high as a result. Also, it seemed like the seat had a bit of a dip that was even more noticeable when riding.

When I was ready to go, all I had to do was turn on the ignition/display and the bike was ready to go. The RMX has electric start with fuel injection and even a convenient fast-idle lever on the bars so there is no need to reach down and pull a button on the throttle body. Even when the engine was cold, the bike started easily and continued to start well, even when in gear. We began riding almost immediately, allowing for very little time for the bike to warm up. The EFI did its job as the bike ran smooth when cold with no hesitations or popping.

Once we entered the first single-track, I was quickly reminded that this bike is a little heavy as I missed the first two corners. Unfortunately, compounding the issue is a weak front brake with a 250mm rotor. It would be nice if Suzuki would upgrade the rotor to maybe 270mm to help with more braking power. As we rode more, it became less of an issue as I became more comfortable with the bike’s braking zones. The motor is super smooth and easy to ride because of its heavily restricted exhaust and somewhat restricted airbox. The good news is that if you want more power, it will be very easy to find. In stock form (after you remove the throttle stop), the power is closer to a 350 four-stroke than a 450. The torque is very smooth with no real hit.

We got into some flowing singletrack and the bike was fun. Just like the RM-Z motocrosser, the RMX chassis is narrow between your legs and responds very well to rider input from your knees when standing. Its balance of cornering and stability is excellent. This is something I feel the Honda CRF450RX and the Yamaha YZ-F and WR-F models struggle with. With the ease of turning and smooth power delivery, the Suzuki gives you the confidence to ride with the gas on and accelerate much sooner in the corners. The suspension works well as long as you hit your marks. If you mistime a G-out, you are going to feel it bottom as it is a little soft. Additionally, because the suspension is a little soft, it can go a little deep in the stroke resulting in an aggressive and quick rebound that can be a handful.

As we entered some slower, rocky technical sections, I discovered the clutch can fade quite a bit. I had to be very careful not to slip the clutch as it would almost completely go away. Again, once I became more familiar with the bike, I focused more on gear selection and staying off the clutch. I should note that the clutch lever pull was definitely on the stiff side. An aftermarket clutch such as a Rekluse Core EXP 3.0 system would be a worthwhile upgrade on this bike. The five-speed gearbox worked well with smooth shifting and reasonable spacing between its wide ratios. First gear was perfect in the tight sections with rocks but didn’t fall off too quick when you started gaining momentum. Second gear was almost as good as first in the slow sections unless you were pointed uphill and naturally pulled for much longer. Third gear was normal and, once the trail opened up, it was perfect.

Hill climbs were manageable for the most part, unless it was excessively steep and long. With the extra weight and choked-up engine, it had a hard time pulling third gear. I am guessing with maybe a slip-on muffler and opening up the airbox, you would be more limited by skills than machine. As for fuel range, we rode a full tank and the low fuel light came on at about 37 miles. I added my reserve bottle and we made it back with ease. My suggestion would be if you plan on a ride of 40 or more miles, bring gas with you. If you normally ride more than 50 miles at a time, you may want to look into an aftermarket oversize tank.

Overall, this bike was much more fun than I expected. Handling, cornering, and stability are trademark RMZ features and proved to be the same on this bike. The power was smooth and easy to ride. I’m average height and I was comfortable on this model, and I think a shorter rider would also be comfortable. The engine is fuel injected, has been around for a while, and has proven to be reliable. The Showa 47mm spring fork and Showa shock are proven and easy to tune as well. The RMX450Z is a perfect bike if you’re looking for a fun trailbike that is gas-and-go with not much to worry about.

TECH SPEC

 
PRICE $8999
ENGINE 449cc, liquid-cooled, single-cylinder four-stroke
TRANSMISSION/FINAL DRIVE 5-speed/chain
MEASURED HORSEPOWER 40.48 hp @ 9120 rpm
MEASURED TORQUE 27.02 lb.-ft. @ 6460 rpm
FRAME Aluminum twin-spar
FRONT SUSPENSION Showa 47mm fork adjustable for compression and rebound damping; 12.2-in. travel
REAR SUSPENSION Showa shock adjustable for spring preload, high-/low-speed compression damping, and rebound damping; 12.2-in. travel
FRONT BRAKE Nissin single 250mm disc w/ twin-piston caliper
REAR BRAKE Nissin single 240mm disc w/ single piston caliper
RAKE/TRAIL 28°10'/4.8 in.
WHEELBASE 58.5 in.
SEAT HEIGHT 37.4 in.
FUEL CAPACITY 1.6 gal.
MEASURED WEIGHT 272 lb. wet
AVAILABLE Now
CONTACT suzukicycles.com/

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