Replacement engine for an ST 91
03-28-2026 | 02:47 PM
#1
Replacement engine for an ST 91
Afternoon everyone.
About a year ago I got a used Pica FW 190D from a friend who left the hobby. He had been flying it with a Super Tiger 91 two stroke and regular 15% fuel. The engine didn't come with the plane and is not available. I have a Webra 91 2 stroke that is low time and runs well but it is too big to fit into the engine mount. I don't have a smaller 91 but the OS 61 FX drops in without a problem. Four stroke engines won't work because the exhaust manifold and muffler will poke out the top of the cowling and look stupid. Physically this plane looks to be in the 60 size range and while a bit heavy I can't see why the OS wouldn't be adequate. Not overpowered but enough to fly the plane without being constantly about to stall. Thoughts??
Rick H.
About a year ago I got a used Pica FW 190D from a friend who left the hobby. He had been flying it with a Super Tiger 91 two stroke and regular 15% fuel. The engine didn't come with the plane and is not available. I have a Webra 91 2 stroke that is low time and runs well but it is too big to fit into the engine mount. I don't have a smaller 91 but the OS 61 FX drops in without a problem. Four stroke engines won't work because the exhaust manifold and muffler will poke out the top of the cowling and look stupid. Physically this plane looks to be in the 60 size range and while a bit heavy I can't see why the OS wouldn't be adequate. Not overpowered but enough to fly the plane without being constantly about to stall. Thoughts??
Rick H.
04-01-2026 | 08:08 PM
#3
My Feedback: (19)
The OS 65 / 75 and 95 AX 2 strokes all fit the same mount as the ST. I've made the swap several times. Sadly though, the mounting holes will not line up. Power wise the OS 75 has about the same power as the ST 90 and the OS 95 will run away and hide from the ST90. Have owned all these engines and liked them all but the OS is stronger.
