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Getting Back To Two-Stroke Engines

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Getting Back To Two-Stroke Engines

Old 05-13-2022, 07:34 AM
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Crazy Legs
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Default Getting Back To Two-Stroke Engines

I'm just getting back into the hobby and so I re-built two OS Max H60F Gold Head engines. I noticed that when I choke them with my finger over the carburetor they don't seem to pull fuel steadily like I remember seeing it being pulled with my OS 91 4-Stroke engine. When I choked my 4-Strok engine I could see a very steady stream of fuel being sucked through the translucent fuel tubing that went to the carburetor. Should I see the same level of suction with the 2-Stroke engines? I'm asking because it seems like when I tilt the airplane straight up the engine leans out a little.
Old 05-13-2022, 07:38 PM
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A. J. Clark
 
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Yes If the throttle is open and the carb opening is closed off you should see the fuel zip right up to the carb . Maybe you have a air leek in the fuel line or carb.
Old 05-13-2022, 09:41 PM
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Crazy Legs
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I think I know why I didn't see the "steady stream" of fuel being sucked up through the fuel line that goes to the carburetor: There's a low speed air bleed adjustment port on the front of the carburetor. As long as air can flow through that hole (see photo) then I don't think I'll be able to get the "full" suction I would usually get out of another engine that doesn't have that low speed air bleed port. Let me know if that makes sense. Also, I only have my Servo Low Speed Endpoint adjusted so it shuts off the motor. The Servo doesn't necessarily have to completely rotate the barrel to the completely closed position for the engine to turn off, so that's why air can still get in.

This photo shows how the low speed air mixture adjustment may let air in though the front of the carburetor preventing a steady stream of fuel to be drawn when a finger is placed over the carburetor intake.
Old 05-14-2022, 01:01 AM
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A. J. Clark
 
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Yes sounds like you found the reason.

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