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- ULTIMATE ENGINE MXR CERAMIC & 2141 PIPE COMBO
ULTIMATE ENGINE MXR CERAMIC & 2141 PIPE COMBO
Description
This is the Ultimate MXR Ceramic 3 Transfer .21 Competition Engine Combo with 2141 Ultimate pipe combo. Like its predecessor the MXS, this engine is manufactured by the prestigious Japanese brand O.S. Engines, in this case based on their square stroke Speed B21 engine. Apart from the modifications that the MXS already had, such as the crankshaft and back plate, the sleeve of the MXR has been modified, modifying the ports to be able to vary the inlet and exhaust timing. The inner head has also been modified and includes the innovative FlowMax venturi 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 is equipped with the same cooling head as its predecessors (MXS, MTS). 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 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.
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 MXS, the MXR 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 MXR crankshaft features DLC treatment and 2 tungsten weights to increase rotational inertia and improve mid-rev feel.
BEARINGS
The MXR comes with the original OS ceramic bearing in the rear and Ultimate Racing steel double sealed in the front.
VENTURI
The MXR comes with the 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 of the MXR 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.
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%.