The new FSa-81 is a direct replacement for the FS-70 Surpass II, offering greater power and throttle precision in a compact and lightweight design. The crankcase mounting dimensions allow the FSa-81 to slot into the same mount that an FS-70S II would for an instant power upgrade. Like the FSa-56, the crankcase breather system has now been incorporated inside the engine to negate the need for an external vent and the excess oil that emanates from it. A propeller locknut assembly is of course standard. The new F-5030 silencer is very effective, thanks to its internal baffle and carefully matched internal volumes and passages. The design allows a huge range of outlet positions to accommodate almost every model. Even the distance away from the engine can now be adjusted. The latest 60RA carburettor features a ‘constant velocity’ inlet for improved throttle response and reduced spitting.Weight: 556g 19.63oz Displacement: 13.26cc 0.809cu.in. Bore: 27.7mm 1.091in. Stroke: 22.0mm 0.866in. Power Output: 1.3ps/11,000r.p.m. Practical RPM: 2,200~12,000 Displacement 13..26cc Bore 27.7mm Stroke 22.0mm Output 1.3ps/11,000r.p.m. Practical r.p.m.Range 2,200?`12,000 r.p.m Weight 610g (including 54g of silencer and manifold)