HELP! Kohler command cv740 bogging/getting rough under load.

[SawAddictedFarmer]

Vertical shaft cv740. Completely torn apart and all new gaskets putting it back together. It runs perfectly and idles incredibly smooth. My issue is it starts bogging down and changes from smooth to more like pop pop pop but not horrible under load. Going uphill or tall grass is what seems to trigger it although it it way more likely to happen if the ground is rough. I've tried 2 different scamazon carbs and now it has a stens on it. They all run the same. Any choke under load kills it fast but I can choke it some if it's not under load, go to far and it makes it sound like the issue it has under load. The plugs rich but I don't know what to do. Seems to me like it's the hydraulic lifters of the carb. Anybody got any idea what's up? @EFSM have you run into this at all?

 

[EFSM]

Vertical shaft cv740. Completely torn apart and all new gaskets putting it back together. It runs perfectly and idles incredibly smooth. My issue is it starts bogging down and changes from smooth to more like pop pop pop but not horrible under load. Going uphill or tall grass is what seems to trigger it although it it way more likely to happen if the ground is rough. I've tried 2 different scamazon carbs and now it has a stens on it. They all run the same. Any choke under load kills it fast but I can choke it some if it's not under load, go to far and it makes it sound like the issue it has under load. The plugs rich but I don't know what to do. Seems to me like it's the hydraulic lifters of the carb. Anybody got any idea what's up? @EFSM have you run into this at all?

When you say you had it all apart, does that mean you had the engine pan off? I’ve never seen issues with the hydraulic valve lifters once they are bled properly. Could you post the engine spec number or some pictures so I can get an idea of what year engine this is? I suppose this is the old single barrel style carb and not the new Walbro double barrel.

 

[64poncho]

I've tried 2 different scamazon carbs and now it has a stens on it.

Have you checked the float level on the new carbs? What was wrong with the original carb?

 

[SawAddictedFarmer]

When you say you had it all apart, does that mean you had the engine pan off? I’ve never seen issues with the hydraulic valve lifters once they are bled properly. Could you post the engine spec number or some pictures so I can get an idea of what year engine this is? I suppose this is the old single barrel style carb and not the new Walbro double barrel.

Everything was completely out just because it was new to me. Yes it is the old style single barrel carb with the accelerator pump on the side. As soon as the lifters came out they went in a can of oil until they got put back in. CV740-0008

Have you checked the float level on the new carbs? What was wrong with the original carb?

I've not opened any of the new carbs and I suspect they're not adjustable. It came with a scamazon carb on it and a NIB one as well. Thought that was my issue so I tried the stens.

 

[SawAddictedFarmer]

I wonder if I'm losing a coil under load? The other thing is the fuel tank level is currently above the engine and it still has a fuel pump. Any chance it's pushing too much fuel into the carb. Also it after normal before we bought it and when it drove it off the trailer after 2 hours of back roads is when I first noticed it. Maybe I didn't push it hard enough when we were looking at it though.