How do you get 200-size power from a 120-size engine? O.S. calls it the 155FS-a. You can see the size advantage here, but appreciating the 2.6 hp power requires a trip to the field. And since the 155FS-a is a pumped 4-stroke, you'll be able to enjoy the power at all times, regardless of tank position, attitude or fuel level. It's power designed to endure, too. Instead of venting oil, the 155FS-a's novel recirculation system uses it to bathe working parts in a constant stream of lubrication. The result is less friction and wear…and less cleanup in the long run. It's a great choice for giant-scale power and scale sound…from O.S. br br You'll find basic specs on the 155FS-a below. But for complete information about the 155FS-a 4-stroke, visit its product page at br OSMG0998 br Displacement: 1.548 in³ (25.6 cc) br Bore: 1.323 in (33.6 mm) br Stroke: 1.126 in (28.6 mm) br RPM Range: 2000-10000br Output: 2.6 hp @ 10000 rpmbr Weight (wmuffler): 31.75 oz (900 g)br br Join O.S.