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2013 Suzuki RM-Z 250 test

Following on from our test on the 2013 RMz-450 (which you can read by clicking here) we sent ace videographer and all action motorcycle racer Ty Kellett back up the M5 to Apex to test the 2013 RMZ-250. Here’s his opinion on the 450’s smaller sibling.

“The ergonomics of the RMZ250 feel different to the RMZ450. It feels like a higher ride height and that the foot pegs are higher off the ground. However, once you are in the riding position and up and running you don’t really notice it and it then doesn’t seem such a high bike like you think at first.You can move around easy and there’s plenty of room to stretch out, which I personally like because my style is pretty loose, especially according to Jeff! I felt I could put the bike where I wanted and the ergonomics almost naturally positioned me with my body weight in the middle. The bike felt light and I can’t say I struggled to put the bike where I wanted on the track.

“The handling is mint!! When you get to race pace the bike tracks and turns very good. When you’re cornering with aggression you can properly pop out of the turn with confidence, the bike turns fantastic. The only thing I would say is that I think the bike with standard set up favours an expert status rider, or at least someone who’s more aggressive in their riding…. no wonder I liked! The bike feels that it handles better the faster you go. We were riding on wet wood chip and loamy soil so that may have given that impression more but it certainly felt like a bike that wanted a good thrashing!

“When jumping the bike, same as the RMZ450, it is not as strong as the cornering, but when you learn how the bike is going to react; naturally you get more confident. With a bit of time in the bank I felt more assured in throwing it about, but for me it didn’t have that feeling right away. The only thing I was not sure about was when you go to grip the bike with your knees it feels like there is nothing to grip and my feet did slide up the bike a few times. Admittedly it was wet and mucky but it just didn’t seem to have that contact point with the rider like some other bikes.

“The new suspension setup on the forks works really well. I had to make the compression a little harder at the start due to the bottoming out just a little bit too soon when entering corners. But with a few clicks it was sweet and I could really attack the corners.

“For a 250 I felt that the deep wood chip would zap a bit of power, but it certainly didn’t feel like it! There is plenty of power. The power delivery was very smooth, but you really had to have the bike on song, again probably favouring a good standard rider more than a tentative one. I initially thought I was revving it too much, but when I tried to ride higher gears it would just bog. This may have been down to the deep wood chip, the gearing, or both bearing in mind the track conditions and lay out but I felt out of the box it’s still a bike that likes to ridden hard at the high end of the RPM’s.

“When I first got on to the bike the gear box was quite notchy. This did improve as I rode, but I if I was going to improve anything it would be the way it changes gear. No doubt a decent aftermarket clutch would help the cause, but then very rarely when doesn’t it? And I guess it depends on how serious you are as a racer. When it came to starting the bike, it was very easy, normally it would be first or second kick. However when hot it would not start too easy, but with the hot start in it fired really easy so bear that in mind.

“Overall I’m really impressed with the bike, it jumped well once I was use to it, the power is there and it delivers it well, probably just a little higher up the RPM’s than some of it’s competitors. I just wanted to go faster and faster and with the positive handling you feel you are able to do this. So I guess a bike that encourages that and gives you the confidence to do so is a good one? For me it just depends on what level you are with your riding to capitalize on what the 2013 RMZ-250 has to offer.

The technical stuff….

Piston

Based on racing data and on-track experience, Suzuki redesigned the piston of RM-Z250. With a new shape – designed through Finite Element Method (FEM) analysis used in factory racing – new piston is 3% lighter than in the previous model while retaining rigidity. It has slightly thinner skirt walls, a shorter piston pin and narrower piston pin boss to help cut weight but not sacrifice performance and durability. A reinforcing rib on the intake underside adds rigidity; the exhaust underside is left alone for best lubrication and cooling efficiency.

Transmission & Shift Cam

The RM-Z250 gets an all-new 5-speed transmission, and the RM-Z450’s is updated and refined for more precise shifting performance. Suzuki changed the shape of the shift cam in both motorcycles to deliver that shifting precision plus smoother shift feel.

Electrical

Suzuki updated the electronics that help control the battery-less fuel-injection systems on the RM-Z450 and RM-Z250. The new ECM on both motorcycles now has a higher-performance processor for more powerful engine management. This component upgrade increases response all the way from the rider’s throttle input to the fuel delivery through each bike’s multiple hole fuel injector. And since the ECMs are now waterproof, they resist damage from water and mud, and that helps keep racers at the front of the pack. The electrical systems also get a new magneto with increased power-generating performance for easier starting. And with revised settings in the ignition coil, the RM-Zs deliver strong roll-on power and increased throttle response.

Camshafts 

Both intake and exhaust cam profile are changed on RM-Z250.  The nose angle and lift curve of intake camshaft is increased and exhaust cam timing is revised to achieve higher balance between high performance and ease of power control. The RM-Z450’s intake cam timing and lift are revised, giving the bike’s power a more linear output for better control.

Radiator 

The RM-Z250’s cooling efficiency is increased thanks to a redesigned radiator fin and revised water hose routing, making the bike’s high-performance power output more stable, even in the most demanding conditions. RM-Z250’s also features new by-pass hose routing to simplify occasional radiator maintenance.

Chassis Design Concept

Racers know that, in and out of a corner, precision cornering and race-track stability has always been a prime feature of Suzuki’s motocross bikes. But that doesn’t mean engineers left “good enough” alone. For 2013, the team focused on making both the RM-Z450 and RM-Z250 even more maneuverable, while retaining the bike’s top-notch performance tracking and race-speed stability. With enhanced engine performance as well as refined handling control, the RM-Z450 and RM-Z250 will continue to be the choice of champions, and of those soon-to-become champions.

Frame

To ensure the frame’s rigidity is well balanced, engineers reviewed and refined the shape and construction of the frame and the seat rail. The result is an ideal balance of nimble handling for technical sections and straight-line stability for high-speed sections.

Front Fork

The RM-Z450 and RM-Z250 now use the new Showa Separate Function front Fork (SFF). The SFF works by separating the damper in left leg from the spring housed in the right leg. Dividing the fork’s functions allows for lighter overall construction with reduced friction, resulting in improved damping performance and ride control. The forks’ inner tubes are now 48mm in diameter; the larger size gives higher stability. Spring pre-load is adjustable, by gold-anodized adjuster, allowing a wider range of adjustment settings overall.

Rear Suspension

To maintain the RM-Z’s renowned handling performance, each bike’s rear suspension features setting changes and adjustments to best match with the increased engine performance and front fork changes. Overall, the design allows enhanced suspension performance for a wider variety of riders.

Facts for the Anoraks…..

DIMENSIONS AND CURB MASS

Overall length ………………………………………………………………… 2170 mm (85.4 in)
Overall width …………………………………………………………………. 830 mm (32.7 in)
Overall height ………………………………………………………………… 1270 mm (50.0 in)
Wheelbase ……………………………………………………………………. 1475 mm (58.1 in)
Ground clearance ………………………………………………………….. 345 mm (13.6 in)
Seat height ……………………………………………………………………. 955 mm (37.6 in)
Curb mass ……………………………………………………………………… 106.5 kg (235 lbs)
ENGINE
Type …………………………………………………………………………….. 4-stroke, liquid-cooled, DOHC
Number of cylinders ……………………………………………………….. 1
Bore …………………………………………………………………………….. 77.0 mm (3.03 in)
Stroke ………………………………………………………………………….. 53.6 mm (2.11 in)
Displacement ………………………………………………………………… 249 cm3 (15.2 cu. in)
Compression ratio ………………………………………………………….. 13.5 : 1
Fuel system ………………………………………………………………….. Fuel injection
Air cleaner …………………………………………………………………….. Polyurethane foam element
Starter system ……………………………………………………………….. Primary kick
Lubrication system …………………………………………………………. Semi-dry sump
Idle speed …………………………………………………………………….. 2100 ± 50 r/min
DRIVE TRAIN
Clutch …………………………………………………………………………… Wet multi disc
Transmission…………………………………………………………………. 5-speed constant mesh
Gearshift pattern ……………………………………………………………. 1-down, 4-up
Primary reduction ratio ……………………………………………………. 3.315 (63/19)
Gear ratios, Low …………………………………………………………… 2.153 (28/13)
2nd ……………………………………………………………. 1.764 (30/17)
3rd …………………………………………………………….. 1.470 (25/17)
4th …………………………………………………………….. 1.238 (26/21)
Top ……………………………………………………………. 1.090 (24/22)
Final reduction ratio ……………………………………………………….. 3.769 (49/13)
Drive chain ……………………………………………………………………. DID520DMA4, 114 links
CHASSIS
Front suspension …………………………………………………………… Telescopic, coil spring, oil damped
Rear suspension ……………………………………………………………. Link type, coil spring, oil damped
Front suspension stroke ………………………………………………….. 310mm (12.2 in)
Rear wheel travel …………………………………………………………… 310mm (12.2 in)
Caster ………………………………………………………………………….. 29°20’
Trail ……………………………………………………………………………… 130 mm (5.1 in)
Steering angle ……………………………………………………………….. 45° (right & left)
Front brake …………………………………………………………………… Disc brake
Rear brake ……………………………………………………………………. Disc brake
Front tire size ………………………………………………………………… 80/100-21 51M, tube type
Rear tire size …………………………………………………………………. 100/90-19 57M, tube type
ELECTRICAL
Ignition type ………………………………………………………………….. Electronic ignition (CDI)
Ignition timing ………………………………………………………………… 12° B.T.D.C. at 2100 r/min
Spark plug …………………………………………………………………….. NGK CR8EIB-10
CAPACITIES
Fuel tank, including reserve …………………………………………….. 6.5 L (1.7/1.4 US/Imp gal)
Engine oil, oil change ……………………………………………………… 950 ml (1.0/0.8 US/Imp qt)
with filter change ……………………………………………. 1000 ml (1.1/0.9 US/Imp qt)
overhaul ……………………………………………………….. 1100 ml (1.2/1.0 US/Imp qt)
Coolant ………………………………………………………………………… 950 ml (1.0/0.8 US/Imp qt)

MX Vice Editor || 25

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