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This is giving me fits. I thought it was a "bad gas" issue. So drained, new fuel, fuel filter, spark plugs, changed engine oil and filter, new air filter.

It sputters and misses, and blows black smoke. If you put it under load, then it evens out a little, but still runs rough and blows black smoke, but it evens out a little under load.

I have had the carb off and cleaned it good, no help.

I put on a new carb, changed gas to No-alcohol and some sea foam, still the same.

The choke works, not stuck.

Could it be a stuck valve, or some crud not letting the valve seat? I am kinda at a loss.

We used this mower only a few times last year, the neighbor started mowing our grass up at the barn, so it sat most of last year.

I am only a shade tree mechanic, so need some advice.

Thanks, Gene

Black smoke indicates a very rich condition. How's the air cleaner element?

Doubt it's a valve issue, you'd have low compression and hard starting if a valve were hanging open or badly misadjusted. Wouldn't hurt to check tho.

New carb - OEM or Amazon-Chinese cheapo? I've had pretty good luck with cheap Amazon carbs but they can be hit and miss.

Good hot spark? Bright blue? New plug? New plugs can be bad right out of the box. I've had HORRIBLE luck with Champions, I use NGK pretty much exclusively.

I don't have an answer for you, but I frequent a Cub Cadet forum that has a sub forum dedicated to Kohler engines. I'm sure someone on there might be able to help you.

The main forum is here:
https://www.onlycubcadets.net/forum/index.php

Get all the info on the engine data/serial number plate and post on the sub forum here:
https://www.onlycubcadets.net/forum/for ... y.php?f=50

You'll have to sign up to post, but it's painless and free.

PHPaul wrote: Tue Apr 08, 2025 4:55 pm Black smoke indicates a very rich condition. How's the air cleaner element?

Doubt it's a valve issue, you'd have low compression and hard starting if a valve were hanging open or badly misadjusted. Wouldn't hurt to check tho.

New carb - OEM or Amazon-Chinese cheapo? I've had pretty good luck with cheap Amazon carbs but they can be hit and miss.

Good hot spark? Bright blue? New plug? New plugs can be bad right out of the box. I've had HORRIBLE luck with Champions, I use NGK pretty much exclusively.

Has a new air filter. and yes, new plugs, but might replace them again. The carb was a "no name" I got somewhere, probably Amazon. Thing is, the new carb acts exactly as did the OEM that I replaced. Choke is opening and closing.

Red Dave wrote: Tue Apr 08, 2025 7:40 pm I don't have an answer for you, but I frequent a Cub Cadet forum that has a sub forum dedicated to Kohler engines. I'm sure someone on there might be able to help you.

The main forum is here:
https://www.onlycubcadets.net/forum/index.php

Get all the info on the engine data/serial number plate and post on the sub forum here:
https://www.onlycubcadets.net/forum/for ... y.php?f=50

You'll have to sign up to post, but it's painless and free.

Thanks Dave.

GeneMO wrote: Wed Apr 09, 2025 12:56 pm

Red Dave wrote: Tue Apr 08, 2025 7:40 pm I don't have an answer for you, but I frequent a Cub Cadet forum that has a sub forum dedicated to Kohler engines. I'm sure someone on there might be able to help you.

The main forum is here:
https://www.onlycubcadets.net/forum/index.php

Get all the info on the engine data/serial number plate and post on the sub forum here:
https://www.onlycubcadets.net/forum/for ... y.php?f=50

You'll have to sign up to post, but it's painless and free.

Thanks Dave.

I have made me an account and am waiting to be approved to post. Thanks again, Gene