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Ultimate Racing

Ultimate Racing MXS Engine

Ultimate Racing MXS Engine

Regular price $500.00 USD
Regular price $500.00 USD Sale price $500.00 USD
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 Ultimate Racing MXS Ceramic Competition Engine is a 3 port .21 Off-Road racing engine. Made by the prestigious Japanese O.S. Engines brand and it's based on their square stroke Speed B21 Ty Tessmann II edition engine but has some modifications on the crankshaft as well as on the back plate to improve performance. This engine has more power and returns to idle very quick and smooth.

With this engine you will have a really good power band with a ton of usable power. It has a smooth bottom end which works well on the bumpy track conditions and then has a lot of mid-range pop and feel to it. It is one of the best idling engines on the market. This engine is recommended for 1/8 nitro buggies.

The "Team Edition" concept uses the standard Ultimate Racing Ceramic Competition Engines, but the engines are assembled directly in our factory, completely broken-in and then thoroughly checked by our competition team to extract 100% of the performance. There are many manufacturers that offer pre-break-in services performed on benches with propellers. The problem is that this method only works as a pre-break-in.  It is still necessary to continue breaking in the engine on the track. At Ultimate Racing we wanted to go a step further and offer our customers the possibility of purchasing fully broken-in and ready-to-race engines without the need for any additional break-in on track, i.e. engines that can be used in the most demanding competitions as you receive them, directly from the box. To ensure quality and that all "Team Edition" engines are broken-in exactly the same, we have evolved a fully monitored break-in bench where temperature, RPM and break-in time are controlled at all times. The whole break-in process is performed with the engine perfectly lubricated to minimize the loads and wear of all the parts, significantly increasing its useful life. During each of the break-in stages the engine's resistance torque is also controlled.  Using this parameter, we know when the engine break-in is finished, ensuring that all of our “Team Edition” engines are perfectly broken-in and ready to compete.  Once the break-in process has completed, the engines are dismantled, checked piece by piece and assembled again by our competition team, thus ensuring the highest quality of product reaches our customers.


The cooling head has been redesigned by Modelix. It’s not as low as the B2102 lower profile but it’s lighter so it keeps the center of gravity as low as the B2102 with improving its performance on high temperatures.


The MXS comes with the 21 J3 carburetor. Compared to the original OS 21 J3 carb, 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’s 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 remove the engine.

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


The MXS backplate has been modified. The backplate is CNC machined and made of 7075-T6 Swiss Aluminum. It’s 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.


The crankshaft of the MXS is an evolution of the DLC B2102 but with two balanced tungsten in order to increase the inertia to rotation.


The MXS comes with the original OS Ceramic bearing in the rear and steel in the front.


The engine is supplied with a 6.5mm aluminum venturi.


The sleeve with 3 inlet port and an exhaust port guarantee 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.


Displacement: 3,49 cc

Power Output: 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


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