Adventurous and fast, the Beta RR 4T 390 is a versatile off roader powered by a single cylinder, DOHC, 4 stroke, liquid - cooled engine with a displacement of 385,6 Cc. The engine features die cast cases and new crankshaft, connecting rod, cylinder head and pistons.

The Beta RR 4T 390 also features a new front fork compression piston to improve oil flow and reduce harshness, a new rear shock piston, a handlebar pad borrowed from race edition, and a softer seat.

The engine’s power is kept under control by a six speed transmission with wet multi disc clutch.

As far as prices are concerned, the Beta RR 4T 390 can be yours for no less than $ 9,299.

Hit the jump for more information on the Beta RR 4T 390.

  • 2015 Beta RR 4T 390
  • Year:
  • Make:
  • Engine:
    Single cylinder, 4-stroke, liquid-cooled
  • Transmission:
  • Energy:
  • Displacement:
    385 cc
  • Top Speed:
    75 mph (Est.)
  • Price:


2015 Beta RR 4T 390 Exterior
- image 573767

The Beta RR Enduro project continues to grow and improve, boosted by successes on the racetracks and by the great commitment of the technical and R&D departments in Rignano sull’Arno. The RR Enduro 2015 models are lighter and more agile, and their great power and torque are more easily controlled. They are the ideal bikes for enthusiasts and the winning solution for victory-hungry racers.

The RR Enduro 4T 2015 range evolves with updates to all models of the “RR 4T Factory MY14” version and the introduction of many new technical features. The main objectives during development were to make the bike lighter and easier to control, and improve overall handling making it more enjoyable and easier to ride and, above all, more effective. The engine-block components have been made lighter and redesigned to reduce the inertial masses, and the engine sizes have been reduced to make handling easier and minimise weight. Compared with the larger capacity of the previous model, the absolute power and torque figures remain unchanged thanks to a new camshaft profile and a new exhaust system; in addition, a better distribution of the torque curve has been obtained to get more out of the engines.

2015 Beta RR 4T 390 Key Features:

2015 Beta RR 4T 390 Exterior
- image 573766

•Die-Cast Engine cases (2.2 lbs. lighter)
•All new displacements for optimum performance and handling
•New crankshaft, connecting rod, cylinder head, and piston
•Beta’s ETR(Easy-To-Ride) Engine
•New front fork compression piston to improve oil flow and reduce harshness
•New rear shock piston to reduce heat
•Handlebar pad from Race Edition
•New design seat foam that is softer
•New graphics and color scheme

2015 Beta RR 4T 390 Features and Benefits:


The whole range is equipped with engines that have been completely renewed, both in terms of looks and performance. The total weight has been reduced by 1kg on the 430 and 480 engines, compared with the previous 450 and 498, and by as much as 1.5kg for the 350 (derived directly from the 2014 factory model) and the 390 (which will replace the 400). The central guards have been completely redesigned, made lighter and modified internally to house a new oil-pump drive system, which is simpler and more effective thanks to elimination of a drive gear. The flywheel chamber has been redesigned in order to minimise pumping losses, and the entire shape has been reworked thanks to the introduction of ribs that stiffen the engine block. The covers, clutch and flywheel have also been modified with a view to reducing weight and, at the same time, increasing the rigidity of the parts themselves.

The crankshafts have new shoulders and a new con rod, lighter and with optimised inertia, making the bike quicker to deliver power and more agile thanks to a reduction of the gyroscopic effect.

More specifically, the con rods are shorter and lighter, and feature a new design. The redesign is aimed at reducing the alternating masses and the size of the engines. The 390-430-480 cc engines, in fact, have the entire combustion unit positioned lower down compared to the previous models. This means that masses are more compact and closer to the centre of gravity, significantly improving the bike’s agility.

The piston is lighter and more robust, thanks to a structure derived from Formula 1 called “box-in-box”, which enables a reduction in vibrations and an increase in performance. The gudgeon pin is coated with a Diamond-Like-Carbon (DLC) treatment to minimise friction and wear.

The camshafts were developed with a new profile to boost performance, especially at low speeds, and to provide greater linearity of output. On the 350 and 390 version has been adopted a complete set of titanium valves.

The cylinder features a new design for the water jacket to improve the removal of heat and increase the efficiency of the whole cooling system. The head has been completely redesigned both in terms of the conduits and combustion chamber, in relation to the needs of the new engine sizes, and externally.

The starter motor has been significantly improved and is more powerful and lighter compared with the previous models. The balance shaft has been completely redesigned in relation to the different balancing of the primary masses of the crankshaft unit; the result, also here, is a significant reduction in weight. The intake sleeve has been completely redesigned for the new engine sizes to guarantee better fuel supply, optimal filling of the engine and therefore a better yield, particularly at low rotation speeds.


The silencer has been redesigned with new internal passages and a larger diameter of the manifold connection hose. The performance and precision of engine response have increased considerably, bringing them as closely in line with the different fluid dynamics imposed by the revision of the engine sizes and the combustion unit as possible.


The Sachs USD ? 48 fork developed in close collaboration between Beta and Sachs features numerous important innovations: a new design of the extension piston with “three slot” geometry in order to improve the oil flow and make it more direct so as to absorb violent shocks more progressively. To improve the general smoothness of the fork, particularly on the initial breakaway friction, a spring-support release system has been included to eliminate rotational friction, the design of the sleeves and sheaths has been modified increasing the distance between the slider DUs, also reducing their height. Finally, the spring profile has been redesigned to guarantee better insertion inside the sleeve. All the connections have also been adjusted, increasing precision.

Shock absorber

Ideal for the most extreme off-road riding and compliant with the standards required by FIM regulations.

Handlebar pads

Ideale nella guida più estrema in fuoristrada e conforme agli standard richiesti dalle normative FIM.


The padding has been redesigned with softer foam


The renewed look streamlines and adds character, maintaining the classical Beta colours.


Engine Type Single cylinder, 4-stroke, liquid-cooled
Bore 88 mm
Stroke 63,4 mm
Displacement 385,6 cc
Compression ratio 12,48:1
Valve train DOHC finger follower / 4 valve
Starter Kick- and electric starter
Ignition Kokusan AC-CDI
Spark plug NGK LKAR 8A-9
Lubrication 2 oil pumps
Fuel system carburettor
Carburettor Keihin FCR-MX 39
Clutch wet multi-disc clutch
Primary drive straight toothing Z. 28/76
Transmission 6 gears
Final transmission chain
Engine oil SAE 10W/50 0,8 l. + SAE 10W/40 0,8 l.
Frame Molybdenum steel with double cradle split above the exhaust port
Wheelbase 1490 mm
Max length 2180 mm
Max width 807 mm
Max height 1270 mm
Seat height 940 mm
Ground clearance 320 mm
Footrest height 413 mm
Dry weight 111,5 kg (front 54,5 kg; rear 57 kg)
Fuel tank capacity 8,0 l.
Reserve 1,3l.
Cooling system capacity 1,4 l.
Front suspension Hydraulic USD fork with ø48 mm shaft
Rear suspension Monoshock with progressive compound lever
Shock absorber stroke 135 mm
Front wheel travel 290 mm
Rear wheel travel 290 mm
Front brake Wave disc ø260 mm and double-piston floating caliper
Rear brake Wave disc ø240 mm and single-piston floating caliper
Front rim 21 x 1,6 - 36 holes
Rear rim 18 x 2,15 - 36 holes
Front tyre 90/90 - 21
Rear tyre 140/80 -18
Price $9,299


"Beta engineers were clearly hard at work in preparation for the 2015 model year, with changes announced for its bikes across the board. Substantial updates to the RR 4-Stroke engine (available in 350cc, 390cc, 430cc and 480cc) highlight the coming year’s upgrades, in addition to the inclusion of a Beta/Synerject-developed electronic fuel injection system for the 350RR. The inclusion of EFI on the 350RR marks the first production Beta to be made available with FI, and the system comes with a 42mm throttle body and stepper motor to ensure engine performance remains consistent in a wide variety of conditions." — Motorcycle USA

"Suite and end of Beta Enduro 4T 2015 tests with 390 RR that is suggest the bike assume a heart breaking choice. A motorcycle which, as the range 4-stroke, evolves significantly from the motor side. The replacement for the 400 RR remains as versatile motorcycle? Rejoinder by reviewer team." — Bikes Doctor

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