How
to Adjust the Square K&B Carburetor
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The style carburetor
on left was used on the K&B 40, K&B 61 and K&B
7.5 outboard engine.
The style carburetor
on right was used on the K&B .67, .82, 1.00 inboard, outboards
and ducted fans.
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First of all how
many turns out an needle valve should be is an arbitrary starting
point and should not be considered a correct setting.
If we knew exactly how many turns out a needle should be set you
wouldn't need a needle to adjust. You have learn the sounds
an engine makes tune your engine properly. |
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A good starting
point for the main needle is about 4 to 5 turns out. To adjust
the main needle loosen the lock nut slightly and turn the main
needle in. clockwise, until it stops. DO NOT FORCE IT. You could
place a piece of fuel tubing on the fuel inlet nipple and blow
through it and screw it in until the flow stops, be sure the
throttle barrel is in the full open position. Now unscrew the
main needle 4 to 5 turns. |
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Next set the idle
needle with the head about flush or slightly protruding from
the brass receptacle it screws into. DO NOT TRY TO SCREW THE
IDLE NEEDLE IN UNTIL IT STOPS. Doing so can ruin the spray
bar end and make it impossible to obtain a correct setting.
See Bell Mouthed
The barrel stop
screw does just that. It stops the barrel from closing completely
and it also is a cam screw as it rides in an angled
groove which allows the barrel to move in and out as it's
opened and closed. See Carb
Designs
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Typically you will
see a gap between the end of the idle needle and the end of
the spray bar with the throttle in the full open position.
This gap is usually 1/16" or slightly more.
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Now proceed to:
"How to adjust an aero engine
carburetor" or "How
to adjust a marine engine carburetor"
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