This is the OS B2103 Type R engine with OS T2100SC exhaust system.
The OS B2103 Type R engine is a 5-port long-stroke engine that offers great power at medium-high speeds. The crankcase, the crankcase cap and the carburetor feature a new design. The new DLC-coated crankshaft has two tungsten counterweights for smooth rotation and better balancing. It shares the same new features as the Type S engine except the cylinder and the cooling head which has a standard round shape.
The long-stroke off-road engine put a high value on beasty power in mid-high speed range.
The crankcase, carburetor, cover plate, crankshaft and inner head are designed new.
All the parts are interchangeable to those of TYPE S’s.
A newly designed 5-port cylinder & piston set (5 scavenging port+ 3 exhaust port)
A standard round type outer head
A newly designed 22E carburetor for producing high power
Includes the OS T2100SC exhaust system
Displacement : 3.49cc
Bore : 16.27mm
Stroke : 16.80mm
RPM : 4000-42000 rpm
Max output : 2.64hp/34000 rpm
Weight : 354gr
Exhaust : T2100SC
Port : 5-port