JD 620 poor idle down

asimon01 · Sep 30, 2016

Hello, I have a john deere 620 tractor that I put a carb kit in and it ran really good for a day or so. I started it one day and started sputtering at take off and when you pull the throttle back the governor takes over and keeps it running by cycling the throttle. Im going to check for vacuum leaks now, but any ideas from the video?
thanks

asimon01 · Sep 30, 2016

how do you upload a video/view it. I uploaded it and I don't see it

Steve@Advance · Sep 30, 2016

Yes, do check for vacuum leaks.

Try enriching the idle mixture.

Also be sure the idle stop screw is adjusted in enough to keep the engine running when you over ride the governor to idle speed.

asimon01 · Sep 30, 2016

thanks, to enrich the mixture you adjust the two screws on the bottom of the engine side of the carb?

Steve@Advance · Oct 1, 2016

This explains it well. If you don't have a tach, just try to count it off, you'll get close enough.
Carb adjust

fixerupper · Oct 1, 2016

If it ran well for a couple of days your settings are probably close to being right. My gut tells me some junk is stuck somewhere in the idle circuit.

Steve@Advance · Oct 2, 2016

All I do is click the link, goes directly to it.

Or go to Youtube, search John Deere 620 Throttle Speed Control

buickanddeere · Oct 3, 2016

There is a procedure in the operator's manual for setting up the carb. Aim for a little bit leaner than the factory calls for on the idle jets.
Is the manifold casting around the summer/winter valve cracked?
Was the manifold removed from the head ?

buickanddeere · Oct 3, 2016

It sounds like you have been guessing. Call 1-800-522-7448 for the operator's manual.

JD 620 poor idle down

asimon01

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Steve@Advance

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asimon01

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