Ultimate Engine MXR v.2 Ceramic motor + Airmax air filter

Ultimate MXR v2 Ceramic 3 Transfer .21 racing engine with Ultimate Airmax filter. Like its predecessor MXR, this engine is manufactured by the prestigious Japanese brand O.S. Engines and is also based on their Speed B21 square-stroke engine (bore to stroke ratio 1:1).

In addition to the modifications that the MXR engine already had, such as the crankshaft, backplate, modified housing and the innovative FlowMax 6 and 6.5 mm Venturi (diffuser insert), the v2 version comes with a modified crankcase. All of these changes were made to increase performance, or more precisely, to achieve higher performance without increasing fuel consumption.

With this engine you get a really good power band with a lot of usable power. It has a smooth bottom that works well on bumpy tracks, and then has a lot of power and feel in the midrange. 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). It has a very low center of gravity and has been designed to focus most of the airflow directly on the glow plug. By cooling the glow plug, we achieve more stable carburation and idling.

Carburetor
The MXR v2 is again supplied with a 21 J3 carburetor. Unlike the original OS carburetor, its high-speed needle holder has been redesigned to better cool the fuel flow to the carburetor, reducing carburetor temperature and consequently making it more stable with great idle stability, better fuel consumption and overall engine performance.

The carburetor comes with a carburetor boot ring from Ultimate Racing. This ring has been designed to guarantee the best possible carburetor seal.

In addition, the carburetor slide uniball joint has also been modified with two stops instead of one. Thanks to this new modified design, you can easily adjust the angle of the uniball joint without having to disassemble the engine. This carburetor offers higher tuning accuracy, which is a very interesting advantage for experienced drivers.

Rear cover
As with the MXR model, the rear cover has been modified. It is CNC-milled from Swiss 7075-T6 aluminum. It has been milled to improve the flow of gases to the piston and improve engine efficiency and power.

Thanks to its design, you can remove the cover without damaging the connecting rod, even when it is in the bottom position (PMI). The side grooves allow easy removal of the crank without having to use any tools that could damage it.

Crankshaft
The crankshaft has a DLC treatment and 2 tungsten weights that increase rotational inertia and improve feel in the mid-range.

Bearings
Comes with a genuine OS ceramic bearing at the rear and a dual-sealed Ultimate Racing steel bearing at the front.

Venturi Insert
The MXR v2 comes with two venturi inserts, 6 and 6.5mm Ultimate Racing FLOWMAX. The innovative design, which is longer than the standard O.S. insert and wider at the base, ensures that the bottom of the insert and the carburetor are exactly the same diameter. This new geometry improves dynamics and provides additional power, allowing the use of smaller liners without reducing power, and consequently reducing fuel consumption.

Head liner and piston
Based on the excellent MXS base, the head liner has been modified, modifying the channels to allow the intake and exhaust timing to be varied, thus achieving higher power without increasing fuel consumption.

The liner with 3 intake and 1 exhaust channels guarantees low fuel consumption with very high, yet smooth and linear power.

Both liner and piston are made of high-strength aluminum, which increases their durability.

Crankcase
This engine features a new crankcase that improves internal fuel flow for higher power.

Airmax Air Filter
The AIRMAX concept is to achieve maximum airflow to the carburetor while respecting the external dimensions of the filter to remain compatible with most 1/8 off-road vehicles and bodies. This is achieved by using a short, large diameter molded rubber connecting 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 performance.

The rubber connecting tube is highly durable to prevent unwanted damage.

The filter comes with pre-lubricated single-layer foam and includes a filter cover with marked holes that can be used on rainy days.

The package includes 2 adjustable plastic brackets that are suitable for mounting on different models. One is used to mount higher or lower. The other is used to mount closer or further in a horizontal position. Both brackets have adjustable holes that provide some freedom for easy installation.

The package includes 4 screws and 2 plastic straps for complete assembly of the filter and brackets.

TECHNICAL DATA

• Displacement: 3.49 cm3
• Output power: 2.61 HP at 34 000 rpm.
• Practical speed range: 4 000 - 42 000 rpm
• Bore x stroke: 16.40 x 16.40 mm
• Head liner: 3 + 1 channel
• Rear ball bearing: ceramic
• Front ball bearing: steel
• Crankshaft: 14 mm
• Carburetor: 21 J3
• Glow plug: P3 Turbo
• Exhaust: rear
• Recommended fuel: Nitrolux Energy3 16%-25%