This is the Ultimate MXR v3 Ceramic Competition Combo, a complete ready-to-fit package that includes the Ultimate MXR v3 Ceramic Engine, the Ultimate Racing 2141 Super Sonic Exhaust and the Ultimate Airmax Air Filter with oiled foam. All three components have been jointly selected and optimised to work as a single unit, extracting maximum performance in competition. The engine is manufactured by the prestigious Japanese brand O.S. Engines, based on their square-stroke Speed B21 racing engine.

In addition to the modifications already present in the previous version — the crankshaft, the rear crankcase cover, cylinder/piston set, the innovative 6 and 6.5mm FlowMax venturi and the crankcase work to achieve greater power without compromising fuel consumption — the v3 introduces a new, less sensitive high-speed needle that makes it easier to find the optimal tuning point.

With this combo you will have an incredible power curve delivering spectacular usable power at all times. It provides smooth, linear power at low RPM — making it perform perfectly on bumpy tracks — while delivering strong power at mid and high RPM with outstanding feel. It is one of the engines with the best idle on the market.

What is included in the combo:

Engine highlights:

• Carburettor: Modified OS21J3 carburettor with exclusive needle carrier and high-speed needle for more stable operation and more precise tuning.
• Crankcase: Same as the v2, where the crankcase was reworked to improve internal fuel flow, delivering an extra margin of power and efficiency.
• Filter: All Ultimate MXR v3 engines include a complete Ultimate Airmax filter set.
• Head: The Ultimate MXR v3 uses the same head as its predecessor. This 8-fin head has a very low centre of gravity and is designed to direct the majority of the airflow directly onto the glow plug. By cooling the plug, carburation and idle stability are both improved.
• Venturi: The MXR features the new 6.5mm FlowMax venturi. Its innovative design is longer than standard O.S. venturis and wider at the base. The new geometry improves fluid dynamics, delivering extra power and a notable improvement in engine run time.
• Rear Cover: The characteristic red crankcase cover of Ultimate engines is machined from Swiss 7075-T6 aluminium bar and features two enlarged ports that improve engine fuel flow, increasing power and improving consumption.
• Liner and piston: Starting from the solid MXS foundation, the Ultimate MXR engine assembly has been redesigned with modified transfers to alter intake and exhaust timing, achieving more power without compromising fuel consumption.
• Bearings: The Ultimate MXR v3 uses an original O.S. Engines ceramic rear bearing and an Ultimate Racing dual-sealed steel front bearing.

Engine technical specifications:

• Displacement: 3.49 cc
• R.P.M. (power): 2.65 PS @ 34,000 rpm
• Stroke: Square 16.40 x 16.40 mm
• Liner: 3 + 1 ports
• Rear bearing: O.S. Ceramic
• Front bearing: Ultimate Racing Steel
• Crankshaft: 14mm balanced with two tungsten counterweights
• Carburettor: O.S. 21J3 modified with exclusive needle carrier
• Glow plug: P3 Turbo
• Engine weight: 345g