O.S. Engine OSMG0990 110FS-a Compact Four-Stroke Unit  [OSMG0990]

Reliable compact drive from the O.S. Engine OSMG0990 110FS-a

The O.S. Engine 110FS-a Four-Stroke is designed to give more usable power without adding bulk. Offering about 12.5% more output than the FS-91SII while retaining a comparable size, it is suitable for a broad range of models.

Cleaner operation through smarter lubrication

This model channels blow-by back to lubricate internal parts, which lowers friction and extends engine life while keeping oil off the airframe. That reduces the need for messy oil drains and makes post-flight care easier.

Flexible muffler orientation for neat installs

The F-5040 muffler can be rotated a full 360 degrees for optimal exhaust routing and fit. It also contributes to a rich exhaust tone, and the familiar mounting pattern eases swaps from older FS-91SII units.

User-friendly installation and upkeep

With a reversible carburetor and a narrower cam housing, installation and setup are more straightforward. The tighter tolerances and updated internals reduce routine maintenance, helping pilots spend more time in the air.

For enthusiasts wanting robust four-stroke performance in a compact package, the O.S. Engine 110FS-a Four-Stroke balances power, sound and reduced maintenance demands.