One new feature, no major changes, same great low price

By Allan Brown, www.dirtrider.com

Those who read Dirt Rider’s 2021 250 Four-Stroke Motocross Shootout know the Suzuki RM-Z250 was not included; despite the bike being unchanged mechanically, the 2021 model was late to arrive Stateside. After taking delivery of Suzuki’s 250 four-stroke motocross bike when it became available a couple of months after the comparison test, we ran it on our in-house dyno, weighed it, measured the seat height, and took it to several tracks around SoCal. We became familiar with Suzuki’s new MX-Tuner 2.0 system and experimented with cost-free suspension modifications to dial in the bike. Although the RM Army’s quarter-liter motocrosser is behind the competition in some ways, it still has charms that make it enjoyable to ride.

2021 Suzuki RM-Z250 Engine

The RM-Z250′s fuel-injected DOHC four-stroke engine, with its 13.75:1 compression ratio and associated five-speed gearbox, has not changed since its most recent revamp in 2019. It remains a kickstart-type engine in an effort to keep weight and cost down. For the racers out there, there is the Suzuki Holeshot Assist Control (S-HAC) that features three modes: the base mode with standard power, mode A for hard surfaces or slippery conditions, and mode B for heavy traction with a more aggressive launch.

One key feature of the RM-Z250 not seen on many other 250F motocross bikes is a dual-injector fuel system, with a primary injector in the throttle body and a second injector in the airbox. The second injector is placed much further back in an effort to give the fuel-air mixture more time to mix and cool before entering the engine.

For 2021, the RM-Z250 now comes with Suzuki’s MX-Tuner 2.0 system. The 12V battery needed to power it is sold separately, but everything else is included with the bike. The system is similar to Yamaha’s Power Tuner app, but you will need to plug the Get communication unit into the bike and download the WiGet app onto your smartphone. Once both of these steps are completed, the main difference between this and the Yamaha system is the communication unit’s need for a power adapter; that’s where the 12V battery comes in.ADVERTISEMENT

RELATED: 2021 Suzuki RM-Z250 Dyno Test

While the RM-Z250 is not the strongest on the dyno, the engine runs very well. It’s a midrange powerband with a very nice throttle response, similar to a YZ250F but with less overall power. Keeping the Suzuki in the correct gear is key. Our primary impression was that it seems to sign off a little early. First through third gears are fairly close together and accept upshifts well. Going from third to fourth is a bigger gap; riders will want to be sure and run it out as far as possible before upshifting. The clutch was very solid. When I found myself forgetting to downshift, I abused it a few times and experienced zero fade.

We spent some time using the Suzuki MX-Tuner 2.0 system and found its operation was very similar to the Yamaha’s. There are some preprogrammed maps, but creating our own custom maps was easy enough. We came up with a few that seemed to improve torque feeling and made each gear feel just a little longer; this mostly helped by reducing the number of shifts per lap.

2021 Suzuki RM-Z250 Suspension

The RM-Z250 comes equipped with a KYB Air-Oil Separate (AOS) coil-spring fork and a KYB shock featuring low- and high-speed compression, low- and high-speed rebound, and spring preload adjustability. These are excellent components with the potential to be the best in the class.

Unfortunately, comfort was evidently not taken into consideration when Suzuki came up with these suspension settings. The shock is borderline stiff, but adjustable. The fork, however, is a jackhammer. Spring rates of 5.0 Nm front and 52 Nm rear are more commonly seen on a 450. Overall it seems that a pro-level rider could run this stock suspension setup on a full-scale supercross track. It would also be perfect for a 200-pound novice or intermediate-level rider.

In standard form, the RM-Z250′s suspension is best suited for shorter fair-type tracks that don’t get all that rough, such as Perris Raceway in California or Dade City MX in Florida. We spent some extra time working on suspension adjustments in an effort to see just how much room there was for improvement without having to spend money on the bike. The shock was easier to improve on than the fork; lowering the sag to the 105mm to 107mm range and opening the compression adjusters a few clicks was helpful.

With the stiffer spring rate, the fork felt good on jumps, flat landings, and under heavy loads. Conversely, they did not work well on smaller chop during corner entry. Opening the compression was slightly helpful, but the fork was going a few inches into the stroke and would ultimately stop. This made them almost too harsh. We began to open the rebound in an effort to keep it higher in the stroke; this seemed to complement the softer compression very well as the rebound adjuster has a small effect on compression. The more we opened the rebound, the better the fork felt. Fortunately, because of the stiffer spring rate, the fork never went too deep in the stroke, which would have caused an uncontrolled rebound effect.

After we were no longer left with compression and rebound adjustments, we decided to lower the oil level in the fork. This adjustment is rarely done by the consumer, but it’s free, and it’s easy to do. First, for testing purposes, we removed 40cc of oil from the right fork leg by removing the fork, turning it upside down, and forcing oil out from the air screw in the cap. This change was a noticeable improvement, so we went ahead and removed the same amount of oil from the left leg.

Removing oil from both fork legs was the single biggest improvement we made on the suspension. Although still on the stiffer side, it was now able to travel further through the stroke under braking. We ended with fork compression at 15 clicks out and the rebound at 21 clicks out. If you’re a lighter rider, it may be possible to remove even more oil. As for the shock, we didn’t go far from stock other than setting the ride height close to the 105mm range.

2021 Suzuki RM-Z250 Chassis/Handling

The RM-Z250′s handling is borderline amazing. It’s no secret that Suzuki motocross bikes are known for their excellent cornering ability, and the 2021 RM-Z250 lives up to that reputation, cornering easily yet remaining stable on straights. Even with unusually stiff suspension, the bike will still rail every inside rut on the track. If it had softer spring rates, something more suited to a 150- to 170-pound rider, we could only imagine the yellow machine might turn on a dime.

With such sharp cornering capability, you might think the RM-Z250 would be unstable at third-gear speeds or higher, but there’s reasonable stability to go along with the bike’s turning prowess; this is something the Honda CRF250R can’t claim. The chassis is quite good, and components such as suspension, brakes, and wheels are all very high quality. The only thing I would change would be the grips, though that’s down to my own personal preference.

Ergonomically speaking, the bike felt a little tall, yet compact. The Renthal Fatbar 821-bend handlebar is a touch low in comparison to the 839-bend on the 2021 Honda CRF250R and 2021 Kawasaki KX250. Even with the stiff fork springs, the RM-Z250 rides a little stink bug, like a Honda. It’s definitely nice and narrow between your legs and might be more suited to a smaller rider. The shifter also seems a touch short. Sitting on the RM-Z, you are clearly on top of the bike; the seat is very flat from front to back and the 821-bend handlebar does not have much rise.

How Does the 2021 Suzuki RM-Z250 Ride?

It’s easy to say the RM-Z250 is slow and the suspension is too stiff, and while these are all true, they also only apply when comparing it to another bike. On its own, the Suzuki is a very fun motorcycle to ride. The engine is manageable with good throttle response and a powerband that you can ride aggressively without getting tired.

It also adds an element that some riders have been taking for granted: shifting. Because the powerband is slightly narrower than the 2021 Yamaha YZ250F, I found myself shifting gears far more often, cornering in second, upshifting two gears to fourth down the straights, and then double-downshifting into the next corner. It’s kind of fun and keeps you on your toes. We were able to improve slightly on broadening the power with the MX-Tuner 2.0. It didn’t change the shift points, but did help each gear run out a little longer.

Overall, the RM-Z250 is a quality motorcycle with plenty of power and good components. It might not be winning shootouts, and it doesn’t have the most power on the dyno, but that does not take away from the fact that it is still a good bike. The yellow machine handles very well, is easy to manage on the track, and is the lowest-priced bike in its category. It would be best suited for riders moving up from a 125cc two-stroke, more budget-conscious riders, or veteran riders getting back into the sport.

Gearbox

Helmet: Arai VX-Pro4

Goggle: Spy Foundation

Jersey: Alpinestars Racer Compass

Gloves: Alpinestars Techstar

Pants: Alpinestars Racer Compass

Boots: Alpinestars Tech 10

2021 Suzuki RM-Z250 Specifications

MSRP:	$7,899
Engine:	DOHC, liquid-cooled single-cylinder
Displacement:	249cc
Bore x Stroke:	77.0 x 53.6mm
Compression Ratio:	13.75:1
Transmission/Final Drive:	5-speed/chain
Dirt Rider Measured Horsepower:	36.3 hp @ 11,500 rpm
Dirt Rider Measured Torque:	18.6 lb.-ft. @ 9,100 rpm
Fuel System:	EFI w/ 44mm throttle body
Clutch:	Wet, multiplate; cable actuation
Frame:	Twin-spar aluminum
Front Suspension:	KYB Air-Oil Separate (AOS) coil-spring fork, compression and rebound damping adjustable; 12.2 in. travel
Rear Suspension:	KYB shock, spring preload, high-/low-speed compression damping, and high-/low-speed rebound damping adjustable; 11.8 in. travel
Front Brake:	Nissin 2-piston caliper, 270mm disc
Rear Brake:	Nissin 1-piston caliper, 240mm disc
Tires, Front/Rear:	Dunlop Geomax MX33; 80/100-21 / 100/90-19
Rake/Trail:	28.7°/4.9 in.
Wheelbase:	58.5 in.
Ground Clearance:	13.0 in.
Dirt Rider Measured Seat Height:	37.4 in.
Fuel Capacity:	1.7 gal.
Dirt Rider Measured Wet Weight:	237 lb.
Availability:	Now
Contact:	suzukicycles.com