OS OSSP-R21 Shimo Edition 3 Combo Set

Developed in collaboration with O.S. team driver Takaaki Shimo, the O.S. SPEED R21 SHIMO EDITION 3 refines power delivery, durability and consistency in a premium combo package. To maximise performance, this OSSP‑R21 Shimo Edition 3 Combo Set pairs the engine with TR03 EFRA2196 + MR05. Updates include a new 9‑port cylinder liner, a newly treated piston for longer service life, and crankcase exhaust spacers that smooth power from low to top end. The carburettor’s Dust Cover Ring helps prevent fuel leakage and air ingress for a cleaner, more stable idle, while the deep gold outer head and venturi complete the new look. Part number SCH‑OS1FG01.

Refinements in this latest SHIMO EDITION focus on responsive drivability and reliability over extended use. Using the provided spacers on the crankcase exhaust section, the engine delivers a more linear feel across the rev range. Combined with the supplied TR03 EFRA2196 + MR05, the combo is configured to maximise performance as supplied.

Key Features

• Crankcase exhaust spacers (included) promote linear power from low to top end
• 9‑port cylinder liner and newly treated piston for enhanced longevity
• Carburettor Dust Cover Ring helps reduce fuel leakage and air ingress for stable idle
• Distinctive deep gold outer head and venturi finish
• Performance combo includes TR03 EFRA2196 + MR05

Specifications

• Displacement: 3.49 cc (0.213 cu.in.)
• Bore: 16.08 mm (0.633 in.)
• Stroke: 17.20 mm (0.677 in.)
• Output: 2.80 ps / 2.76 hp / 35,000 rpm
• Practical rpm range: 4,000–45,000 rpm
• Engine weight: 347 g (12.24 oz)

What’s Included

• O.S. SPEED R21 SHIMO EDITION 3 engine
• TR03 EFRA2196 + MR05
• Glow plug T‑RP7
• Reducer φ8.5
• Exhaust seal ring
• Dust cap set 12‑30 (φ3, φ16, φ18)