OS 91 FS w/pump
10-29-2002, 08:12 PM
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OS 91 FS w/pump
I have a new OS 91 FS w/pump that I have installed in a UCD3D. I was following the manual procedures for break in, but I am having problems with the needle valve settings. I started at 3.5 turns out. Engine runs great. When I open the needle valve (up to a max of 5 turns out) Engine still runs great but there is no change in RPMs. Engine does not seem to be running lean and idles well. I just can't get it to run super rich. I just want some input so I don't trash this motor! I am new to 4 strokes and no one in my local club has experience with a pumped 4 stroke. HELP!!! 
10-30-2002, 07:24 PM
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OS 91 FS w/pump
contempo,
At 3-1/2 turns out, your engine is about as rich as it can go. Opening the needle won't do much, since the carb is already taking as much fuel as it can.
We're not sure what you mean by trying to get it to run "super rich". If you want to hear it change like a 2-stroke, well it won't happen. 4-stroke engines won't give you distinct differences in sound like a 2-stroke engine will.
At 3-1/2 turns, you're at a very rich setting. The engine can be leaned inside of 2 turns when flying. Use a tachometer to help you set the engine. It's not really possible to get the optimum setting by ear.
At 3-1/2 turns out, your engine is about as rich as it can go. Opening the needle won't do much, since the carb is already taking as much fuel as it can.
We're not sure what you mean by trying to get it to run "super rich". If you want to hear it change like a 2-stroke, well it won't happen. 4-stroke engines won't give you distinct differences in sound like a 2-stroke engine will.
At 3-1/2 turns, you're at a very rich setting. The engine can be leaned inside of 2 turns when flying. Use a tachometer to help you set the engine. It's not really possible to get the optimum setting by ear.
