IMR FXR 450 21/18 Motocross 450cc

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€5,289.90

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Unleash your full potential with the IMR FXR 450 21/18, a 450cc motocross bike designed for pure adrenaline. Thanks to its punchy 46hp engine and ultra-lightweight aluminum chassis, every turn becomes an experience of absolute precision. Combining raw power and maximum safety with its IMR Racing braking system, this machine is the ideal ally for demanding riders. At XtremRS, we support your passion with expert service, personalized advice, and a 2-year warranty to ride with complete confidence.

IMR

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Product details

450cc 4-Stroke Engine: The High-Performance Heart of This 450cc Motocross

Powered by a water-cooled 450cc 4-valve single-cylinder engine, this machine delivers a maximum power of 46 hp (35 kW) ready to take on any terrain. The 4-valve cylinder head optimizes volumetric efficiency and combustion for a sharp response at low revs and sustained power all the way to the redline. The reliable and instant electric start frees you from the traditional kick-starter: a simple button is all it takes to wake up the engine, a major asset for both racing and leisure. To go further in choosing your machine according to your size and skill level, check out our guide on how to choose a dirt bike for teenagers or adults looking for power and control.

5-Speed Gearbox: Transmission Tailored for the 450cc Motocross

The 5-speed manual gearbox features ratios specifically designed for motocross: short first gears for acceleration and overcoming obstacles, and long upper gears for top speed at the end of straightaways. Shifting is precise, allowing for active riding utilizing both engine braking and acceleration. This classic, robust, and proven architecture easily handles the generous torque of the 450cc engine, ensuring exemplary longevity even under heavy stress.

Chassis and Ergonomics: IMR Pro Aluminum Serving the 450cc Motocross

The "IMR Pro" aluminum perimeter frame and swingarm form the backbone of this motorcycle. This manufacturing choice combines torsional rigidity for cornering precision with controlled flexibility for shock absorption, all for a featherlight weight of 145 kg fully fueled. The 1490 mm wheelbase ensures reassuring stability at high speeds without compromising agility. The 950 mm seat height and 6.5 L fuel tank create an ergonomic design tailored for adult riders, offering complete freedom of movement to attack whoops and banked turns. Don't forget that safety gear is your primary insurance: check out our recommendations on essential motocross gear and best practices for riding with peace of mind.

Adjustable Suspensions: Top-Tier Damping for Your 450cc Motocross

Up front, the bike features a 940 mm hydraulic inverted fork offering 300 mm of travel, adjustable for compression, rebound, and preload. This inverted architecture stiffens the steering assembly for surgical guidance and exceptional resistance to brake dive. At the rear, the 482 mm shock absorber, also fully adjustable, manages the progression of the aluminum swingarm. Whether you are riding on a sandy track or hard-packed terrain like the circuit of La Roche-en-Brenil, every click of adjustment fine-tunes the handling to match your style and the day's conditions.

IMR Racing Braking System: Safety and Bite on This 450cc Motocross

Stopping power is entrusted to IMR Racing calipers: a dual-piston caliper up front gripping a 270 mm disc, and a single-piston caliper in the rear on a 230 mm disc. This setup ensures massive deceleration power that can be modulated down to the finest touch, essential for braking late into corners or handling steep downhills. The generous front disc surface dissipates heat efficiently, preserving braking endurance lap after lap without premature fading.

21/18-Inch Aluminum Wheels: The Standard Grip of the 450cc Motocross

Mounted on anodized black aluminum rims, the 21-inch front and 18-inch rear dimensions adhere to competition standards. The large front diameter rolls effortlessly through ruts and braking bumps with reduced inertia, while the 18-inch rear optimizes traction and tire warm-up times. Aluminum lightens unsprung weight, further enhancing suspension performance. A setup ready to fit your favorite tires to turn grip into fast lap times.

1. What type of rider is this IMR FXR 450cc motocross designed for?

With a power output of 46 hp, a weight of 145 kg, and a seat height of 950 mm, this machine is clearly geared towards experienced teenagers and adults. The 450cc displacement and developed power indicate intensive sports use, suitable for riders who already have the necessary experience to handle such energy on a track or in enduro.

2. What are the technical details of this off-road quadbike's engine?

The engine is a 450cc single-cylinder, water-cooled with 4 valves. It develops a power of 46 hp (35 kW) and is paired with a 5-speed manual gearbox. It features an electric starter, which makes getting started much easier.

3. Is the suspension adjustable to fit my weight and the terrain?

Yes, the suspension is fully adjustable. Up front, you have a hydraulic inverted fork with 300 mm of travel and a length of 940 mm. At the rear, the shock absorber is also adjustable with a length of 482 mm. This allows you to calibrate stiffness and preload according to the rider's weight and the type of track.

4. What materials are used for the chassis and structure?

The chassis and swingarm are made of aluminum, following the IMR Pro model design. This construction combines lightness and rigidity, which is essential for a high-performance 450cc motocross. The 21-inch (front) and 18-inch (rear) aluminum wheels complement this lightweight and sturdy structure.

5. Is the braking system adapted to the vehicle's power?

Yes, the braking system is sized for the engine's power. Up front, a 270 mm disc with a dual-piston caliper (IMR Racing model) provides strong stopping power. In the rear, a 230 mm disc with a single piston (IMR Racing model) completes the system. This "IMR Racing" configuration is designed to offer a precise response in racing conditions.

6. What is the seat height, and is it comfortable for an adult?

The seat height from the ground is 950 mm. This dimension is standard for dirt bikes of this displacement and allows most adults and tall teenagers to put their feet on the ground. The riding position is designed for efficiency in jumps and corners, rather than for road cruising comfort.

7. Is the fuel tank large enough for a day on the track?

The tank capacity is 6.5 liters. For intense sports riding, this offers reasonable autonomy for several race or training sessions without having to constantly refuel, which is a very practical feature during track days.

8. Is it possible to adjust the bike's geometry for motocross?

The basic geometry is optimized for off-roading with a wheelbase of 1490 mm. Although specific geometry adjustments (like rake angle) are not listed, the adjustable hydraulic inverted fork and rear shock allow you to optimize the dynamic behavior and stability of the 450cc motocross on various types of terrain.

9. What are the delivery times and conditions for this vehicle?

Delivery takes place within 5 to 8 working days, by appointment. Shipping is free for vehicle purchases over €500. Payment is secured via 3D Secure. Please note that while the site mentions free 24/72h shipping, for a vehicle of this size, standard XtremRS logistics times (5-8 days) generally apply for assembly and inspection.

10. What warranty is offered on this 450cc motocross?

The motorcycle is covered by a 2-year warranty, excluding wear parts (consumables) and safety equipment (helmet, gloves, etc.). This warranty covers manufacturing defects and major parts, giving you peace of mind for your first seasons of riding.

The use of Pit bikes / Dirt bikes / Quads is strictly prohibited on public roads. The use of vehicles such as Dirt bikes, Pit bikes, Quads must take place on terrain adapted for this practice (tracks, private land).
The user must wear appropriate protective equipment and be under adult supervision.
The purchase of a Dirt bike, Pit bike, or Quad by a minor over 14 years old is carried out under the responsibility of an adult. Only a single rider is allowed on the vehicle.
Purchases on the XtremRS website must be made by an adult.
Warning: Dirt bikes / Pit bikes / Quads / Pocket quads are motorized machines and not toys.
It is recommended to have assembly and maintenance performed by a professional. We recommend users check the condition of the vehicle before and after each use.

General

Brand IMR
Reference IMP-4965

Features

Engine Thermique 4 Temps
Front Wheel Size 21"
Rear Wheel Size 18"
Engine displacement 450cc
Power 46 CV
Brake Type Freins à Disques Hydraulique
Cooling Liquide
Clutch Manuel
Transmission Chaine
Seat height 950
Wheelbase 1490
Starter Type Electrique
Gearbox 5 Rapports

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