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Force .28 4 Needles?


Old 06-12-2019, 11:09 PM
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Default Force .28 4 Needles?


I have been browsing through multiple forums but I did not find a clear answer.

In my quest to search for the right needle setting I was confused to what is the LSN on my engine. I have 1 screw at the servo side (black) and 1 screw on the outer side (brass). One of those is never mentioned. I assume the black one is the LSN but what does the brass one do?? I read it is a kind off spray needle??

Who can explain?
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Old 06-13-2019, 03:14 AM
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You will have either a 2-adjustment carb or a 3-adjustment carb. The two adjustment (needle) carburetor will have a high speed or main needle which is in the fuel inlet fitting (usually brass) and will stick up perpendicular to the carburetor body. The low speed or idle mixture adjustment will usually be located in the center of the throttle slide valve near where the servo linkage attaches from the servo. There will be a screw in the carb body near the center either in the rear of the carb (typical) or the front of the carb (typically for Buggy/Truggy installation). This screw controls the idle gap only.

The only difference a 3-adjustment carb will have is there will be a slotted screw (usually brass) in the end of the carburetor body opposite side to the throttle valve. This adjustment can be changed to manage the midrange fuel mixture. Not usually needed, but some engines need this adjusted for best performance. It’s generally accepted to leave this adjustment with the screw head flush with the carburetor body.
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