More FS-91 Surpass Diesel Conversion

I continue to work on the FS-91 conversion. I think that the carb for this size engine is becoming the sticking point. The acceptable air/fuel mixture range is rather narrow and the model carbs lack the proper tuning. Since model diesel fuel, especially without ether, approaches air/fuel ratios of gasoline I decided to try a Walbro carb designed for gasoline fuel. These are common on small portable gasoline engines. A straight manifold was made to adapt it. I spent quite a bit of time trying to get the carb working. There is some conflicting information about setting up the Walbro carburetors on the internet, which me cost some aggravation and time. I have the engine running with the Walbro pumped carb. Some fine tuning and a velocity stack is still necessary. It will be a nice addition with the built in pump and better fuel regulation. A new manifold is also in the works. I look forward to test flying the engine soon.

OS FS-91 diesel conversion with Walbro carb.

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