JD 520

Does anyone know, can the choke be installed backwards?

The only way we can get this tractor to run, is with the choke pulled all the way out. With the choke pushed in, it floods the engine. Its almost like the butterfly valve is in backwards.

Has the carb been rebuilt?

(quoted from post at 19:50:17 10/21/18) Has the carb been rebuilt?

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Yes, I believe it had been.

Is this a tractor you just purchased? Why would you suspect that? Has someone had the carb apart? Can you remove the inlet from the carb and look at the choke to see it operate?

(quoted from post at 19:59:59 10/21/18) Is this a tractor you just purchased? Why would you suspect that? Has someone had the carb apart? Can you remove the inlet from the carb and look at the choke to see it operate?

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My father recently restored the tractor and he had a friend rebuild the carb. The friend said that he put the carb back together as it should be. I have not yet tried to remove the inlet and look at the choke. From what I understand, the butterflies bolt on, so there should be only one way for the shaft to be installed. Just doesn't make sense to me why; choke out- tractor runs fine, choke in- tractor loads up.

YES, they can and I've built many carbs that were backwards when sent to me. Very east to do. The spring will NOT clock correctly and the butterflies will just float around in there and usually when you throttle up, the suction will suck them shut and flood it out until you let off throttle. Just depends where the spring wedges in as to where it jambs up. Good rule is. if the plates just fall into place easily....it's wrong. They require some thinking and do NOT go in as one would think. When installed correctly..the blade goes rearward at bottom and forward at top to open. When in wrong, the blade will tilt back at top and forward at bottom to open and will also hit the vent tubes. Should never hit vent tubes if in right. The "T" goes to the top facing you . Once it is on correctly, now the spring will line up right and so will lever and all will work as the spring loaded choke it was designed to be. Takes a little "studying" to figure out how it was meant to work. One of my customers said " I put it back in just as it came out ". Probably did. Wasn't right to begin with. First pi shows plate hitting tube (wrong) second shows 1/4" from hitting tube (correct) plate mounts off center of shaft,short half to top (T) and large half to bottom BUT must tilt FORWARD at top and rearward at bottom to work.

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If the rebuild consisted of some solvent , compressed air , remove/replace the main jets/nozzles . The most critical areas were missed .
There are six idle ports that are virtually invisible and are often plugged . Plus several internal passages to clean require removal of the steel balls .

another quick way to tell if blade is on wrong....if you can't hardly get a screwdriver on the one little screw and you wonder who designed this stupid thing that way?.....it's in wrong. If in right, ALL screws will be easily accessed.

(quoted from post at 06:28:18 10/22/18) another quick way to tell if blade is on wrong....if you can't hardly get a screwdriver on the one little screw and you wonder who designed this stupid thing that way?.....it's in wrong. If in right, ALL screws will be easily accessed.

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Thanks for all the replies and pictures. This will surely help me try to figure this out.