This is the Ultimate MXR v2 Ceramic 3 Transfer .21 Competition Engine with Ultimate Airmax Filter. Like its predecessor the MXR, this engine is manufactured by the prestigious Japanese brand O.S. Engines, and it’s also based on their square stroke Speed B21 engine.

Apart from the modifications that the MXR already had, such as the crankshaft, the back plate, the modified sleeve and the innovative FlowMax venturi in 6 and 6.5mm, the v2 version comes with a modified crankcase. All these changes have been made to improve performance, more specifically, to achieve greater power without compromising fuel consumption.

With this engine you will have a really good power band with a ton of usable power. It has a smooth bottom end which worked well on the bumpy track and then has a lot of mid-range pop and feel to it. It is one of the best idling engines you can find on the market.

COOLING HEAD

The MXR v2 is equipped with the same cooling head as its predecessors (MXS, MTS, MXR). This 8-fin cooling head has a very low center of gravity and has been designed to focus most of the airflow directly to the glow plug. By cooling the glow plug we get a more stable carburetion and idle.

CARBURETOR

Once again, the MXR v2 comes with the 21 J3 carburetor. Unlike the original OS carburetor, its high-speed needle holder was redesigned for a better refrigeration of the fuel flow into the carburetor, lowering the temp of the carb, and consequently it is more stable with a great idle stability, improves fuel mileage and overall engine performance.

The carb comes with the Dust Cover Ring from Ultimate Racing. This ring has been designed to guarantee the best sealing of the carburetor.

Besides this, the uniball joint of the carb slide was also modified with two stoppers instead of one. With this new modified design, you can easier adjust the angle of the uniball joint without having to disassemble the engine.

This carb offers a higher accuracy tuning, a very interesting advantage to experienced drivers.

BACKPLATE

Same as in the MXR, the v2 backplate has been modified. The backplate is CNC machined and made of 7075-T6 Swiss Aluminum. It has been milled to improve the gas flow going to the piston and improving engine efficiency and performance.

Thanks to its design, you can remove the backplate without damaging the conrod even when it is on its lower position (PMI). The lateral grooves allow to easily remove the backplate without having to use any tool that can damage it.

CRANKSHAFT

The crankshaft features DLC treatment and 2 tungsten weights to increase rotational inertia and improve mid-rev feel.

BEARINGS

It comes with the original OS ceramic bearing in the rear and Ultimate Racing steel double sealed in the front.

VENTURI

The MXR v2 comes with two venturies, the 6 and 6.5mm Ultimate Racing FLOWMAX venturi. With an innovative design, longer than the standard O.S. venturis and wider at the base, unlike all others, makes the inferior part of the venturi and the carburetor have exactly the same diameter. This new geometry improves fluid dynamics, providing extra power that allows the use of smaller venturis without decreasing power, and as a consequence improves fuel mileage.

SLEEVE AND PISTON

Starting from the great base of the MXS, the sleeve has been modified, modifying the ports to be able to vary the inlet and exhaust timing to achieve more power without compromising fuel consumption.

The sleeve with 3 inlet port and an exhaust port guarantees a low fuel consumption with a very high but smooth and linear power.

Both, the sleeve and piston are made from a high strength aluminum bar to improve its durability.

CRANKCASE

This engine includes a new crankcase to improve the internal flow of fuel with the aim of improving performance by achieving extra power.

AIRMAX AIR FILTER

The AIRMAX concept is to achieve maximum airflow to the carburetor, while respecting the external dimensions of the filter to try to fit most of the 1/8 offroad cars and bodies. This is achieved by means of a short, large-diameter tapered rubber connector tube that accelerates airflow and an internal filter structure with a larger surface area, without compromising engine protection. The result is a noticeable increase in engine power and performance.

The rubber connector tube is highly resistant to prevent unwanted damage.

The filter is supplied with a pre-oiled single layer foams, and includes a filter cover with pre-marked holes that can be used on rainy days.

Includes 2 adjustable plastic brakets to fit different cars. One is to fix it higher or lower. The other is to fix it closer or further horizontally. Both brackets have adjustable holes to give some leeway for easy adjustment.

Includes 4 screws and 2 plastic ties for complete mounting of the filter and brackets.

ULTIMATE EFRA 2142 OFF ROAD SUPERSONIC PIPE SET W/ MANIFOLD

In this SUPERSONIC update, the gas flow has been improved to achieve a higher top end speed compared to its predecessor.

This pipe set provides a precise and linear throttle response in high RPM range with a great top end speed. This pipe set will provide great power and speed at high RPM.

This exhaust system includes the pipe, the manifold, 2 short springs, 2 medium springs, 2 long spring and 2 manifold gaskets.

TECHNICAL SPECIFICATIONS

Displacement: 3,49 cc

Power Output: 2.65 PS/2.61 hp @ 34,000 rpm

Practical Range RPM: 4,000 - 42,000 rpm

Bore x Stroke: 16,40x16,40mm

Sleeve: 3 + 1 ports

Rear Ball Bearing: ceramic

Front Ball Bearing: steel

Crankshaft: 14 mm

Carburetor: 21 J3

Glow plug: P3 Turbo

Exhaust Position: rear

Fuel type: Recommended Nitrolux Energy3 16%-25%.