300 utility run away throttle update

Corona Boy · Aug 18, 2014

I had the typical ah hah moment after my last post. OOf course its the throttle pin in the carb plate. Only. That wasn't it. Tractor will not remain at idle. Governor hooked up or not, it will slowly increase speed. As idle speeds up, the accelerating quickens. Only way to slow it back down is to force idle by hand, throttle thru governor won't do it. If left to herself she would probably rev till she blew up. I am puzzled.

RC Brooks · Aug 18, 2014

I had a problem with my 480 case like that. I hooked the governor linkage up, upside down on the carb. But in your case, you said it will do it without the governor hooked up? Do you have spring return on your carb? If so, is it connected correctly? I.E., is it trying to pull the butterfly open rather than closed?

Your RPM will be limited by air and fuel of course. So all else being correct the only wild theory I could offer is that your carb is set rich and you have an opening in your intake hose between the carb and the head, effectively allowing it to accelerate.

I'd still lean towards linkage issues, but just throwing other ideas at you.

mkirsch · Aug 19, 2014

What do you mean "governor hooked up or not?"

The governor can't NOT be hooked up to the carburetor, if everything is installed properly.

A 300's governor is the same torsion bar type as an H or an M. There is a tab on the end of the torsion bar and a slot in the front of the carburetor. The tab has to fit in the slot, or you will get weird governor behavior depending on which side you missed it by. Either it will rev uncontrollably, or it will not rev up at all.

D Slater · Aug 19, 2014

Hand throttle is working the external lever on the engine side of the governor? Throttle tube shaft is correct in notch? Pin good in front of throttle tube shaft? Vertical linkage rod from throttle tube shaft down good? If all above okay, remove the side cover on the governor. See if the spring is pushing the rocker lever to rear of tractor when hand throttle is set to idle. Also look for stuck or damaged weights on the horizontal shaft or the bearing and slide damaged or stuck that slides on shaft to let weights close.
If the carburetor throttle shaft is free to move without any governor linkage restricting it, as air pulls through the throttle plate it would keep moving it open.

teddy52food · Aug 19, 2014

Just how do you force idle it by hand????????????

300 utility run away throttle update

Corona Boy

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RC Brooks

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mkirsch

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D Slater

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teddy52food

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