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ID # 34790096

2025 Beta RX 450 MX

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Overview
A few months ago, Beta's project to expand the boundaries of RideAbility has officially landed in the new Motocross dimension, and the Tuscan company is already set to enhance its models day after day, and to keep its bikes simply at the top. RX 450 was officially the first 4-Stroke Cross bike built by the manufacturer from Rignano sull'Arno, and, for fans, it was also the chance to ride a Made in Beta MX derived from the race prototype, which has now been racing for four years in the MXGP World Championship. While RX 300 2T is a Cross-Country bike launched as an exclusive for the US market in 2021, which started off as an Enduro-derived project, and was brought closer to the world of motocross with a series of specific adaptations. The success of this project and the ever-growing experience in the MXGP World Championship with the 450 4T, have led the Tuscan brand to open the throttle, and configure the RX 300 as a fully-fledged motocross bike, with only a few things in common with the Enduro models. With the Model year 2025, RX 300 underwent a series of important interventions to the engine and to the suspension and frame, which totally break away from the Enduro world and, like RX 450, configure a standalone project, completely dedicated to Motocross. RX 450 also received exciting new updates that sharpen the model's weapons, ready to do battle on MX tracks around the world. Within so many changes for the new RXs, the thing that stays the same is the project's goal: to equip the bike with a frame, engine and components of the highest level, and bring the new frontier of RideAbility to the MX world. What does RideAbility mean for Beta? It means designing and building bikes whose rideability is their core value. Each Betamotor-branded motorbike is designed by the Florentine manufacturer to provide any rider with a motorcycle which is simultaneously easy to ride and high in performance. A product able to extract the best from any rider, thanks to an engine-frame combination which is able to provide a fun ride, without any reason to ever fear the world championship-level performance of the engine. RX 300 and 450 perfectly meet this goal, each in its own way: both represent the perfect combination of power and control, by placing handling and Betamotor's typical family feeling ease of use at the centre of the design, fully focused on uncompromising fun. 

RX 450 4T

Rear sub-frame and filter box: while the rear sub-frame's geometry and the filter box remain the same, the structure has been suitably reinforced in a series of points that stiffen and strengthen it, maintaining lightness and ability to absorb stresses. Access to the filter remains on the left side of the bike, and is extremely easy and intuitive, as well as being tool free.
Suspension: fork and single shock receive a new calibration that enhances the bike's character, both in terms of handling and stability when increasing the pace. The result is an improvement of the features already highlighted by MXGP riders for this model - manoeuvrability and stability that instil confidence in every rider, regardless of their level.
Battery: for safe first-shot ignitions, even in the most severe conditions of use, a new lithium battery has been mounted on RX MY25, with an amperage higher than the previous one, to always have the necessary starting power.
Final ratio: to find the ideal compromise between speed and acceleration, the rear sprocket now has 51 teeth - one more than the previous model – to improve the engine response coming out of corners as well as allowing the engine to build RPM quicker.
Graphics: while the superstructures recently introduced with the new tail remain unchanged, new, more sleek and aggressive graphics have been introduced, which do not lack character in highlighting the racing soul of the model.

The RX 450 already received interesting updates with the new Model Year, all the new features introduced on the RX 300 2T model from Beta are truly a surprise, with the following elements radically enhanced:

Frame: as in the 450, the RX 300 also gets the new frame, specifically dedicated for motocross use, retaining many known proportions from Beta models but with a series of specific redesigned and reinforced parts compared to standard Enduro models. Getting even with the 4T model, the frame acquires a wider main spar than in the past (1 cm more), which does not fear the stresses coming from repeated jump landings, resulting overall much stiffer in the lateral twists generated by high-speed bends. This translates into a precise, stable speed both entering and leaving corners, and which conveys a great feeling of safety in keeping the high performance of the engine tamed. The engine position and mounts are different from the Enduro models, and provide excellent balance both on corners and in jumps.
Rear sub-frame and filter box: in line with the use of the new frame, the new RX 300 inherits its older sister's aluminium sub-frame, as well as the filter box.
Fork: the Kayaba fork with 48 mm stems has greater travel than Enduro models, and receives a new calibration that recreates the perfect set-up together with the new single shock, ensuring a stable, fast and precise bike, yet always easy and precise in its response.
Single shock: the single shock is a new addition to this model, and, as for the 450, it switches to a 50 mm piston that allows greater support in jump landing, thanks to greater hydraulic braking, and guarantees constant performance with heavy use, where temperatures are on the rise. Braking system: Nissin with floating calipers and 260 mm discs at the front and 240 mm at the rear. Particularly at the front, the new caliper - inherited from its older sister - stands out; smaller, lighter and better performing than the previous one, it ensures a much better performance when letting off the throttle at the limit. At the rear, the new pump, featured for the first time on Enduro racing models, is characterised by greater braking power and greater modularity, as well as a different attachment to the frame.
Radiators: RX 450 also gives the new 300 2T its radiators, redesigned at the top compared to the previous model to have a better steering angle and optimize the cooling liquid's internal flow.
Final ratio: the rear sprocket has 49 teeth, instead of 48, for lightning-fast accelerations!
Plastic parts: while the front conveyors retain the same shape, the rear features a new, sleek and aggressive tail section that, not being a load-bearing element, engages in the new aluminium frame. The smaller plastic tank for the RX 300 now has a capacity of about 7lt.
Chain: the chain without o-ring is lighter and smoother than the previous one; all details that matter to make a difference on the track!
Engine and exhaust: if the bike is completely new suspension and frame-wise, the new engine features are even more game-changing, and bring the performance of the RX 300 to the top of its class. The totally new engine consists of a new cylinder with more exhaust and injection timing, a new head with greater compression, and modified intake crankcases to increase ventilation. The result of this intervention is a power unit with a significantly higher thrust than in the past, which still maintains the exceptional thrust at low speeds that has always distinguished Beta's 300 2T, despite the peak maximum power at high speeds being higher, as needed on a motocross track. The greater power of the engine is transmitted to the rear wheel by a totally redesigned 5-speed gearbox, with a specific gear spacing for MX use, and by a stiffer spring that preloads the clutch pack more to prevent slippage. This new ensemble has been perfectly tuned by dedicated mappings, new carburettor calibrations (Keihin PWK 38), and several springs on the appropriately adjusted exhaust valve. The exhaust system, also completely redesigned, offers a dedicated expansion and a short silencer, in full Motocross style.

 

Specifications
Model
RX MX
Category Name
Motorcycles
Year
2025
Manufacturer
Beta Motorcycles
a series of updates common to the two models

Silent handlebar block: comfort and Motocross are notoriously two rather distant concepts, but with the new Silent blocks equipped on this model, this distance is significantly bridged. With the aim of making the grip on the handlebar - and therefore control on the bike - as comfortable as possible, this new model upgrade reduces vibrations and raises the handlebar by 5 mm compared to the previous model, tiring the rider less and thus improving performance.
Footpegs: the 2025 model receives new, less bulky footpegs, with an enhanced grip performance provided to the rider's boot, to keep the bike under control at all times.
Swingarm: the rear wheel axle pin has been reinforced, gaining 2 mm in diameter, for a total of 22 mm. This new component guarantees greater stiffness and torsional resistance, resulting in a bike that is always precise and well steered, even in the most violent accelerations.

To complete our round-up of the bike:

Engine maps: both the RX models are equipped with two specific engine maps (wet and dry), while the 4- Stroke model has also four levels of Traction Control (on/off/active with hard map/active with soft map) to manage the vehicle's significant power in all terrain conditions. The button to select the map and TC is located on the handlebar bumper.
The RX is delivered with customised kickstand and 4 different throttle pulleys, to customise the accelerator
response.

 

chassis
Frame
Molybdenum steel with double cradle split above the exhaust port
Reserve
1,4 l.
Rear Rim
19 x 2,15 - 36 holes
Front Rim
21 x 1,6 - 36 holes
Max Width
830 mm
Rear Tyre
110/90 -19
Wheelbase
1485 mm
Dry Weight
104,5 kg (front 51,4 kg; rear 53,1 kg)
Front Tyre
80/100 - 21
Max Height
1270 mm
Max Length
2170 mm
Rear Brake
Wave disc ø240 mm and single-piston floating caliper
Front Brake
Wave disc ø260 mm and double-piston floating caliper
Seat Height
945 mm
Footrest Height
422 mm
Rear Suspension
Kayaba Monoshock with progressive compound lever
Front Suspension
Kayaba Hydraulic USD closecartridge fork with ø 48 mm shaft
Ground Clearance
335 mm
Rear Wheel Travel
300 mm
Front Wheel Travel
305 mm
Fuel Tank Capacity
7,0 l.
Shock Absorber Stroke
133 mm
engine
ACG
Kokusan
Bore
97 mm
Type
Single cylinder, 4-stroke, liquid-cooled
Clutch
wet multi-disc clutch
Stroke
60,8 mm
Starter
Electric starter
Engine Oil
SAE 10W/50 0,8 l. + SAE 10W/40 0,8 l.
Spark Plug
NGK LKAR 8A-9
Fuel System
Elldor electronic injection
Lubrication
2 oil pumps
Valve Train
DOHC finger follower / 4 valve, intake titanium, exhaust steel
Displacement
449,3 cc
Transmission
5 marce
Primary Drive
Z.31/72
Throttle Body
Ø 46 mm
Compression Ratio
13,5:1
Final Transmission
chain