Super A can't lower carb rpm after carb rebuild

Jason IH · Apr 15, 2011

I rebuilt my Zenith carb # 12613 A. Not the first one I have rebuilt, but also not a pro. They only had a "economy" carb kit for it. I cleaned it all up, and rebuilt it, then mounted it back up. The tractor started without choke, right up. If I move the throttle up, the tractor rises up in rpm, but if I lower the throttle, the RPM's won't lower to LOW. The RPM's will lower from high, but not low. I turn the idle screw in and out and it doesn't change anything. What is wrong? My H I can get it so low, that it will sit there and just HUmmmmmmmmmmmmmmmmmmmmm and puff smoke circles. SO whats going on? Any ideas?

El Toro · Apr 15, 2011

You should check your linkage to make sure its not binding. Check the governor linkage to make sure you have it connected correctly. The idle screw isn't causing the problem. Unhook the governor and see if you can raise and lower the engine speed manually. Hal

rustyfarmall · Apr 15, 2011

Did you use a new carb to manifold gasket? Are the mating surfaces clean? Are the bolts tight? If you replaced the throttle shaft, did you get the throttle plate centered in the bore before you tightened the screws?

showcrop · Apr 15, 2011

Does it have a venturi? is it in correctly?

Jason IH · Apr 15, 2011

I think the venturi is correct, but I will double check. Yes I used all new gaskets. I will also double check the linkage. I will let you know.

thanks,

Jason

Dick L · Apr 15, 2011

If the linkage is free it sounds like the butterfly stop screw on the back is holding the butterfly open to far.
Remember that the stop screw on the back sets the idle speed. What is termed at the idle screw adjusts the air fuel mixture to make the engine run smooth at the stop screw butterfly setting.
If the stop screw was not holding the butterfly open some you could kill the enging by hand by holding the linkage all the way back. The only way any fuel can get into the engine is thru the butterfly opening.

Mike Aylward · Apr 15, 2011

Jason, this is only a guess but is it possible the throttle disk is not centered in the bore at an idle which allows it not to fully close? Something to check, perhaps. Mike

Dick L · Apr 15, 2011

If it was put in backwards it sure might cause that. If the linkage is not hung up it has to be the butterfly is not closing enough.

les hurdle · Apr 18, 2011

Hi
I rebuilt a TSX 155 for a Massey Harris 101 [1946] high rpm ok, idle ok, but when put into gear power dies away...... all valves etc seem to be ok [looking at side plate] any ideas please?
Also, anyone used the Zenith replacement for tsx 155 and reversed the linkage... did it work ok?

Any advice would be welcome [be nice ;-) ]

Les

Super A can't lower carb rpm after carb rebuild

Jason IH

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El Toro

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rustyfarmall

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showcrop

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Jason IH

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Dick L

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Mike Aylward

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Dick L

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les hurdle

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