OS Speed ​​.21 Engine R21 "EURO" II SET - 1DR01

This engine inherits the smooth and easy-to-use feel of the previous OS SPEED R21 EURO Spec engine. and by redesigning the crankshaft counterweight, low and mid-range power delivery has been improved.

This is a combo set:

• Engine R21 Euro II
• TR01(EFRA2098) resonance tube
• MR02 manifold

This set is particularly suitable for race tracks in Europe with longer straights.

The smooth speed drop and idle stability have also been improved, and the optimal performance is also demonstrated in long and hard racing use. Compared to the previous model, every part has been improved, including the outer head with new design to improve cooling performance.

The outer head has the same design as the R2104, which has both high cooling performance and light weight with original laser marking.

The inner head is embedded in the O-ring, which is also used in the R2104. The O-ring is an oil-resistant ring (black).

The 7 port cylinder and piston have a new design with additional cooling holes at the bottom of the exhaust with the redesigned crankcase

The crankshaft was designed specifically for this engine and uses 3 tungsten counterweights. This has improved mid and low speed torque feel and idle performance.

The engine comes with a 21M2 (B) carburetor, popular with many racers for maximum performance. φ8.5 reducer is also standard equipment.


Displacement: 3.49 cc / 0.213 cu.in.
Bore: 16.08mm / 0.633 in.
Stroke: 17.20mm / 0.677 in.
Power: 2.8 hp / 2.76 hp / 35,000 rpm.
Practical speed range: 4,000-45,000 rpm.
Weight: 340g / 11.99 oz.
Standard accessories
Glow plug RP7
Exhaust Seal Ring Dust Cap Kit (φ3、φ16、φ18)