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Discussion Starter #1
I have B&S 16 HP twin engine on a yard tractor. I was attempting to do some carb adjusting. Adjustment procedure, (pictured below), shows an "Idle Mixture Valve Adjustment Screw".



My carb, (photo below), has no such adjusting screw. There are 2 holes at that location but they are both plugged. Anyone have any ideas about adjusting this carb?

 

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You have a newer type carburetor set up on your engine (4 screw pump cover), then the one pictured in your post.

Your carburetor is non adjustable. If you are having any issues related to the carburetor, then you may need to have a look inside as it may need a good cleaning.

Other things to check for that can cause run problems, air leaks between the carburetor and intake manifold, leaks in the manifold itself, leaks between the manifold and the cylinder head.

Also a good idea to check your fuel. Make sure there is no water contamination and that the fuel is fresh.
 

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Discussion Starter #3
Thanks for your input. The engine is running but my concerns are, (1) it seems to be running at very high rpms. (I will try to get a tach on it to see if my suspicions are true), and (2) when I throttle the engine down it stalls at about the 50% speed position on the throttle.
 

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Engine over speed could be due to governor. May need adjustment, or throttle may need to be adjusted. Low speed circuit of carburetor may have a restriction, causing engine to die when throttle reduced. This would require cleaning of the carburetor.
 
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