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Os .91fx

Old 09-30-2002, 05:00 PM
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Default Os .91fx

I've got an old .91 FX turning a 14x10 prop that I have been tweaking with. Using a pitts slimline muffler on a .60 sized Giles 202, it tends to pop and backfire at wide open throttle. On the ground it runs up nice (not sure what RPM) i've set it on the rich side just below max rpm on the high end needle. It idles nicely too and has not made me dead-stick yet.

I would like to start fresh. How many turns out on the high and low needles is a good starting point?

Thankyou for any input.
Old 10-08-2002, 08:28 PM
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Default Os .91fx


It sounds like you're trying to run a lot of propeller. We typically run a 13x8 and allow the engine to turn up.

We generally start with the high-speed needle at about 2-1/2 turns out from closed, and the idle needle is set so that there's about a 4mm gap between the needle and the nozzle when the venturi's opened to the full throttle position.

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Old 10-13-2002, 04:44 AM
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Default OS 91 FX

Put a tuned pipe on that puppy

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