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Overview:
Beta USA entered the motocross world in 2021 with the introduction of their 300 RX, a 2-stroke model that provided a solid platform in design, handling, and looks. Along with the beauty of the bike, the “factory sound” of the 293cc motor was like no other. Riders quickly discovered what Beta likes to call Rideability. Rideability is the smoothness, ease of handling, and overall comfort experienced on a Beta Motorcycle. It encompasses factors such as throttle response, suspension performance, ergonomic design, and stability all contributing to a seamless and enjoyable riding experience. Rideability is the perfect balance of power and agility that provides riders with confidence inspiring control and effortless maneuverability, resulting in a gratifying ride, no matter the conditions.
For the 2025 season, Beta is proud to release the details of the 300 RX updates to enhance its platform. Updates to the 300 include changes to the engine, chassis, and suspension. A new frame highlights the model, one that mimics that of its older 450 brother.
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Features: New durable frame similar to the 450 RX, new design of the rear master cylinder for reduced temperatures and better feel, new aluminum sub-frame, updated cylinder porting and new ignition timing to increase the bike's overall power, five speed transmission, upgraded footpegs with enhanced grip and less bulk, updated expansion chamber, narrower radiators for greater turning radius, updated rear shock with larger body to reduce the oil temperature under extreme use, XTrig FlexFix handlebar mounts, smaller fuel tank, MAP switch to adjust power delivery, adjustable power valve, electric starter, and easy access air filter box.
Handlebar Mounts
XTrig FlexFix isoelastic bar mounts reduce rider fatigue and vibration. Also allows for flexibility in handlebar adjustment
New Aluminum Sub Frame
Similar to the 450 RX the sub frame on the 300 RX is fabricated from aluminum for more strength.
Footpegs
Enhanced grip performance while being less bulky so rider can maintain control at all times
New Bodywork
Along with the aluminum sub-frame, the rear plastic is now a three-piece design. A new, smaller fuel tank (1.8 gallon) has been installed to reduce the overall weight and center of gravity. The MAP switch has been moved to the handlebar pad for ease-of-use.
Engine
Updated Cylinder porting and matched cylinder head along with new ignition timing has increased the bike's overall power. The engine pulls harder and longer
Frame
Dedicated for motorcross use, Chro-moly with a larger backbone to increase stiffness while enhancing the turning. The new frame also has an updated mounting for the new rear brake master cylinder.
Exhaust
An updated expansion chamber attached to a shorter silencer specific for moto.
Suspension
Closed cartridge 48mm KYB front fork and the rear shock have been updated with new valving for better overall performance. 50mm shock body reduces the oil temperatures under extreme use during long motos.
| MODEL | 300 RX |
| ENGINE TYPE | Beta Built single cylinder, 2-stroke, liquid cooled, with BPV power valve system and counter balancer, electric start with back-up kick starter sold as an option |
| BORE | 72mm |
| STROKE | 72mm |
| DISPLACEMENT | 293.1cc |
| COMPRESSION RATIO | 13.3:1 |
| VALVE TRAIN | Beta Progressive Valve (BPV) |
| IGNITION | AC-CDI Kokusan |
| SPARK PLUG | NGK BR8ECM |
| LUBRICATION | Pre-Mix |
| FUEL SYSTEM | Keihin PWK 38mm |
| CLUTCH | Wet Diaphragm-style |
| TRANSMISSION | 5 Speed |
| FINAL DRIVE | O-ring chain |
| FRAME | Molybdenum steel / Double Cradle w/ quick air filter access |
| WHEELBASE | 58.6" |
| SEAT HEIGHT | 37.2" |
| GROUND CLEARANCE | 13.4" |
| FOOTREST HEIGHT | 16.6" |
| DRY WEIGHT | 219 lbs |
| FUEL TANK CAPACITY | 1.8 US Gallons |
| FRONT SUSPENSION | 48 mm KYB AOS Closed Cartridge with adjustable compression & rebound |
| REAR SUSPENSION | KYB 50 mm body with adjustable rebound and high/low speed on compression adjustment |
| FRONT WHEEL TRAVEL | 12.0" |
| REAR WHEEL TRAVEL | 11.8" |
| FRONT BRAKE | 260 mm floating rotor |
| REAR BRAKE | 240 mm rotor |
| FRONT/REAR RIM | 21" (Front) 19" (Rear) |
| FRONT/REAR TIRE | Michelin Starcross |
| SPECS | *Specifications subject to change without notice. |
