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OS 61 MAX SF Pumped

Old 01-04-2004, 04:25 PM
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Join Date: Aug 2002
Location: Jackson, TN,
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Default OS 61 MAX SF Pumped

I've been storing this motor for several years, and finally decided to wring it out on a new project. I cannot find a manual or any good info on the engine anywhere. My question is, On the pump unit it has 4 nipples marked IN, OUT (pretty self explanatory), one marked S, which I am assuming is for a tube back to the base of the carb, and one marked R, which I am assuming is a return and should be hooked to the muffler. Are my assumptions correct? Other than that, my only other question is that on the nipples marked OUT and S, there are some type of slot heads that look like adjustments for something, are they of any importance?
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Old 01-05-2004, 12:38 PM
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Location: Monticello, IL
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Default RE: OS 61 MAX SF Pumped

You'll need at least 3 lines to your tank, fuel pickup, vent, and return.

Here are the pump's nipples:

IN--from fuel pickup in tank
OUT--to nipple on carburetor right at the needle
S--from the nipple near the base of the carb, inboard from the fuel nipple at the needle
R--return fuel line back to the tank. It should dump forward bottom of the tank.

Fuel tank vent should run from front top and out the bottom of the cowl/fuselage.

NO muffler pressure is used.

The screws on the back of the pump adjust pump pressure and when the return fuel valve opens. Their adjustment is extremely critical, and should not be moved from the factory-set positions.

If you email us at the address below, we can send the engine's operating instructions to you, since they're no longer on the O.S. downloads page. The O.S. downloads page does detail proper carb-adjusting procedure, though.
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