SV730 Courage Hunting or Surging at idle?

blakeo82

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Hi all,

I hope one of you fine folks have a suggestion or two for me. I was given a cub cadet ltx1050 tractor with a sv730 Kohler engine. Its 4 years old and has 82 hours on it. A head gasket was blown, so I replace them both. The mower sat for one season. Prior to and post repair, the engine revs up and down at an idle. On WOT, seems to run smooth. I think this is called hunting?

What is it doing?

https://youtu.be/S5UR5FfMjTI

I should probably mention, I am very much a newb at tractors and small engine repair.

I ran a can of Seafoam through the gas tank, got some black smoke, not much, no change in idle. I took apart the carb, cleaned it with carb cleaner, tried to remove the idle jet from it but I couldn't get it out easily so I blew air through it real good with my air compressor. Put it back together, no change. The springs and linkage all appear to be at their factory locations.

Do you guys have any suggestions on what I can try? I would certainly appreciate your input. Thanks.
 

bertsmobile1

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Remove the carb and clean out the idle circuit.
Take a couple of good photos before you start so you know where all the linkages go.
If there are multiple holes take close ups so you know which hole / slot things go in.
IF your carb is not on here http://outdoorpowerinfo.com/repairs/#id_kohler then go to parts tree or similar and download the diagram for your carb, blow it up, print it out and have it sitting on the workbench as you pull the carb down, thus you won't breal anything by removing bits that don't come out.
It has an idle circuit and one ( or more ) of the idle passageways is blocked.
 

blakeo82

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Just wanted to update this -

After bertsmobile1's advice, I decided to clean the carb again. I clean and clean, I was just sure I had detailed it enough. When I put it back on, it didn't change a thing.

Disappointed, I decided to order an ultrasonic cleaner. It took about a week to show up. Thirty minutes in the cleaner with water and a touch of dish soap, blew it out real well with the compressor, put it all back together and she idles perfectly smooth!

Thank you for the advice!
 

bertsmobile1

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Congratulations
Thanks for the update.
Feels good dosn't it.
And yes some of the build ups are difficult to remove.
There are times a carb has spent several hours in my ultrasonic cleaner, cam out so hot I could not touch it with a gloved hand and was still not fully clean.
Do yourself a big favour and pop a fuel tap in your system.
I like to put them in front of the fuel pump so the pump, filter and carb can be worked on without a mess or clamping the fuel line.
Turn it off when you have finished and starve the engine.
By far the biggest cause of problems is a deposit of crud in the fuel system and even if the float needle is working properly, a really hot day can lead to heavy build ups in the carb
 
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