The Suzuki motocross line for 2001 features the mini-class standard, the RM80, and a totally new RM125 and RM250. Each Suzuki motocross model includes a full race contingency pack age with over $3 million dollars in cash and certificates up for grabs, plus other benefits exclusively for RM riders.

The RM250 has also been totally revamped for 2001, with similar weight saving performance features as the RM125, but with an eye on improved low-to-mid rpm power and torque. The engine crankcase has been lightened and reduced in length using a right-side mounted water pump with additional weight savings from a thin-wall cylinder head.

Mounted in the cylinder is a new two-piece, two-stage exhaust valve system that works with new exhaust port specs, a lightweight exhaust pipe/silencer and a Keihin carburetor with a throttle position sensor for strong low rpm power. Transmission shift precision and feel have also been improved by switching to gear-type shift-drum option.

The RM250 chassis features an improved balance of frame rigidity, weight placement, swingarm length, suspension calibration and overall geometry. A new Kayaba front fork combines a cartridge/air-bladder system for improved high-speed damping performance, and at the rear is a Kayaba shock absorber with adjustable high/low-speed compression damping. The whole package is wrapped in aggressive new bodywork with a class-leading 212 lb. dry weight.

RM250  AT A GLANCE

• Suggested Retail: $5,899.00
• Engine Type: Two-stroke, liquid cooled
• Bore and Stroke: 66.4 mm x 72.0 mm
• Front Brake: Single Hydraulic Disc
• Rear Brake: Single Hydraulic Disc
• Wheelbase: 1470mm (57.9 in)
• Dry Weight: 96 kg (212 lbs)

The 2001 RM250 engine makes more power and torque, weighs less and is more compact than the previous model's engine. Maximum power output has been increased substantially, with significant mid-range power increases as well. Overall engine weight has been reduced by 1133 grams, compared to the 2000 model's engine. And the new engine is 21.4mm shorter, measured front to rear.

In basic terms, the 2001 RM250's engine has a bore and stroke of 66.4 x72mm for 249cc of displacement. It is liquid-cooled, and its cylinder bore is plated with Suzuki's own race-proven nickel-phosphorus-silicon-carbide coating, known as SCEM (Suzuki Composite Electrochemical Material).

The reduction in weight came from a hard look at every detail of the engine design. The cylinder head, for example, is 4mm smaller in outside diameter (reduced from 115mm to 111mm) and the cylinder head stud bolt circle is 4mm smaller in diameter (reduced from 94mm to 90mm).

Cylinder head wall thickness has been reduced where possible, and the RM250's head is a total of 52 grams lighter. The RM250's cylinder assembly is a total of 450 grams lighter, the reduction in weight coming from reduced wall thickness, shorter cylinder stud bolts and shorter cylinder stud bolt flanges. Reducing the outside diameter of the magneto rotor from 77.5mm to 73.5mm saved 55 grams. And removing material from the primary drive gear saved 18.2 grams.

Weight-saving changes to the RM250's clutch activation and shifting mechanisms saved a total of 85 grams, the most significant including replacing the one-piece steel clutch push rod with a three-piece, two-material (steel/aluminum/steel) clutch push rod, switching to gear-type shift-drum operation, using a hollow shift shaft and making the shift lever out of tubular steel, instead of solid steel. The revision in shift-drum activation also improves shift precision and feel at the shift lever.

Changes made to increase the RM250's power started with a redesign of the exhaust valve system and port shape, which adjusts exhaust port timing to best suit engine rpm, broadening the powerband. The single main exhaust valve used on the 2000 model has been replaced by a two-stage, two-piece exhaust valve. The valves move independently, changing main exhaust port timing as engine rpm increases, resulting in stronger mid-range power and smoother power delivery across the rpm range. The opening of the side exhaust valves - positioned in the auxiliary exhaust ports located on each side of the main exhaust port - has been adjusted to work best with the new dual-stage, two-piece main exhaust valves. The side exhaust valves now move on needle roller bearings instead of ball bearings, for more precise control. And the shape of the main exhaust ports and auxiliary exhaust ports have been modified to improve low and mid-range power delivery.

The RM250's exhaust pipe has been modified for 2001, to work with the exhaust valve and port changes. A slight reduction in exhaust pipe wall thickness saved 150 grams, and a redesigned silencer is between 48 grams for the U.S. model and 55 grams lighter for the non-U.S. model. The exhaust pipe mount has been changed from steel to aluminum, saving an additional 5 grams.

The 2001 RM250's 38mm Keihin carburetor incorporates a throttle position sensor (TPS), and the digital engine control module now uses 3D mapping to determine ignition timing, based on rpm and throttle position, improving throttle response and tractability, especially at lower rpm ranges.

To help make the engine more compact and to move its weight closer to the machine centerline, the 2001 RM250's bolt-on waterpump has been positioned on the right side of the crankcases; the previous model's waterpump was built into the front of the crankcases. The transmission case is also smaller internally. As a result, the crankcases are 21.4mm shorter and 410 grams lighter. And the simplified radiator hose routing allowed by the water pump relocation saved another 95 grams.

RM250 FRONT FORKS

The 2001 RM250's new Kayaba inverted, cartridge front forks have 46mm inner tubes and weigh 800 grams less than the forks on the previous model. A new design improves high-speed-damping response to sharp-edged, harsh terrain and hard landings without compromising slow-speed-damping response to rolling terrain features and in corners. A check plate positioned above the cartridge divides the oil inside the fork into two quantities - the oil inside and surrounding the cartridge, and the oil above the cartridge; a small orifice allows oil to flow through the check plate from one to the other at a controlled rate. The cartridge itself is surrounded by an air bladder containing a volume of air equal to the maximum volume of oil displaced by the piston rod. This design reduces the volume of air at the top of each fork leg, above the oil level, but adds air volume in the bladder surrounding the cartridge, without reducing the total air volume.

All fork designs use pressurized air as a progressive spring, which becomes firmer as fork travel increases. In other words, the fork's ability to deal with sharp bumps and hard landings and resist bottoming increases with travel because, as the fork compresses, the air inside each fork leg is also compressed and internal air pressure rises. To generate enough internal air pressure to respond well and resist bottoming on a given sharp-edged bump or during a given hard landing, a conventional fork must travel - or compress - a certain amount. In a series of sharp-edged bumps - or if a sharp-edged bump follows a hard landing - a conventional fork may run out of travel and bottom out.

This RM250' s new forks have a better ability to respond to series of sharp-edged bumps and an increased resistance to bottoming, based not just on travel, but also on damping piston speed. When the forks encounter a rolling terrain feature or enter a corner, they move at a relatively slow rate - producing a slow damping piston speed. The slow damping piston speed sends oil through the small orifice in the check plate to compress the air contained in the bladder surrounding the cartridge. The total volume of air in the fork is compressed, and normal response is produced, without harshness.

But when the RM250's new forks encounter a sharp-edge bump, they move quickly - producing a high damping piston speed. The high damping piston speed cannot send oil through the check plate fast enough to compress the air contained in the bladder surrounding the cartridge, and only the air at the top of each fork leg is compressed. Internal air pressure increases more quickly without using maximum travel, allowing to forks to deal with subsequent sharp-edge bumps and increasing the forks' resistance to bottoming.

RM250 REAR SHOCK

The latest RM250 uses a new piggyback-reservoir Kayaba rear shock with both high-speed and low-speed compression damping circuits, high-speed and low-speed referring to the rate at which the shock is compressed. At relatively slow shock-

Specifications:

RM250

MSRP:

$5,899.00

DIMENSIONS AND DRY MASS

Overall length:

2175mm (85.6 in.)

Overall width:

840mm (33.1 in.)

Overall height:

1275mm (50.2 in.)

Wheelbase:

1470mm (57.9 in.)

Ground clearance:

335mm (13.8 in.)

Seat height:

965mm (38.0 in.)

Dry mass:

96kg (212 lbs.)

ENGINE

Type:

2-stroke, 1-cylinder, liquid cooled, piston reed

Bore:

66.4 mm (2.614 in.)

Stroke:

72.0 mm (2.834 in.)

Piston displacement:

249.0cc (15.2 cu. in.)

Compression ratio:

9.0/10.5:1

Carburetor:

Keihin PWK38PWJ (w/TPS)

Air cleaner:

Foam element

Starter system:

Primary kick

Lubrication System:

Pre-mix 32:1

TRANSMISSION

Clutch:

Wet multi-plate type

Transmission:

5-speed constant mesh

Gearshift pattern:

1 down, 4 up

Primary ratio:

3.000 (63/21)

Gear ratios:

1st 1.800 (27/15)

2nd 1.470 (25/17)

3rd 1.210 (23/19)

4th 1.000 (21/21)

5th 0.870 (20/23)

Final ratio:

3.692 (48/13)

Drive chain:

520 chain, 112 links

CHASSIS

Front suspension:

Inverted, 20-way comp. & 18 rebound damping

Rear suspension:

Link-type, adjustable preload, 19 comp. 16 low speed, 3 high speed & l8 rebound damping

F. suspension stroke:

31 0mm (12.2 in.)

R. wheel travel:

320mm (12.6 in.)

Rake:

27? 30'

Trail:

115mm (4.53 in.)

Steering angle:

45? (right & left)

Turning radius:

2.3m (7.5 ft.)

Front brake:

Disc

Rear brake:

Disc

Front tire size:

80/100-21 51M

Rear tire size:

110/90-19 62M

ELECTRICAL

Ignition type:

CDI

Ignition timing:

4? B.T.D.C. - 1500 r/min

Spark plug:

NGK BR8EG

Generator:

Magneto

CAPACITIES

Fuel tank:

8.0L (2.1 gal.)

Transmission oil:

850m1 (0.9 qt.)

Engine coolant:

ll00ml (1.2 pt.)