Circa 1980

Design History :-
Designed and manufactured in Japan in 1980 by the OS Engines Manufacturing Company

Design Features:-
Single Dykes Ring at top of piston;
Aluminium Piston with Steel cylinder liner;
Schnuerle porting* with out a baffle on the piston crown;
Ball bearing supported crank shaft

Specifications:-
Bore 0.87 inches;
Stroke 0.85 inches;
Displacement 0.50 cubic inches (8.2 cc);
Max Power 1.8 @ 18,000 RPM;
Practical speed range 2000 to 20,000 RPM;
Weight 13.8 oz

Observations:-
This engine is extreemly powerful for it's size developing as much power as the average 60 size engine.

Click the play button below to view a short video featuring the starting and running of this powerful vintage engine.

* Schnuerle porting is a system to improve efficiency of a valveless two-stroke engine. The intake and exhaust ports cut in the cylinder wall are shaped to give a more efficient transfer of intake and exhaust gases.