Tractor won't govern

T G head · Jun 7, 2013

Have a old John Deere 420 runs fine except it won't rev up when it under a load.How do you adjust it so it will govern right?

Bob · Jun 7, 2013

Tractor is NOT supposed to "rev up under a load", only maintain a constant speed (with a certain % of "droop") as load is applied. If engine is not "running away" (overspeeding) the governor is more or less doing it"s job, although if worn or out of adjustment it MAY not be as RESPONSIVE as it should be.

Is the linkage loose and free to move without excessive play?

I sounds more like you have a "lack of power" issue.

I would venture to guess setting the timing and correcting any problems with air and fuel flow will go a long way to helping your problem.

If NOT, the basic linkage adjustment is to be sure the throttle shaft in the carburetor reaches it"s "wide open" stop JUST BEFORE the governor does.

John B. · Jun 7, 2013

Like Bob said I would check all the things he mentioned. Governors very seldom give trouble. But mine just three weeks ago on an IH 574 Gas Tractor my governor flew apart when I shut it off. I heard something and then when I started it up it went to wide open throttle. Found a good used one on this website for $100. It would of cost $503 if I bought the parts new.

JimB2 · Jun 8, 2013

HI TG, it has been a long time since we had a JD 420 but check fuel flow to carb and the high speed/load adjustment screw on carb. The other common problem was rocker arm shaft would crack at the support bolts and one cylinder valves would not work properly.

JimB

Tractor won't govern

T G head

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Bob

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John B.

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JimB2

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