Carbs have not had adjustable mains for a long time. What these engines do have is too small of an air filter- so watch over that.

two local dealer service managers both said I should replace the carb but since it was still running the warranty would not cover it. I've been keeping the air filter clean. I buy those & oil filters in bulk. this engine has always smelled like it's running rich but has gotten worse of late. I guess this is typical of most new equipment. it's also developed an intermittent engine stall/shutdown. I believe the ignition switch is giving up the ghost. when it cuts out wiggling the key fixes it. and of course it is exactly one month out of warranty.

1. the carburetor could have an internal leak such as a leaking needle / seat. consider an overhaul

2. What is your altitude. high altitude jets may be available

3. has the choke adjustment been inspected

4. Look for fuel leaks around the carburetor, fuel tank and fuel lines and fuel pump.

after a cold start when I put the throttle in the run position the choke is wide open. st louis mo sea level is 535'. no leaks that I can see. i'll be keeping a close eye out for leaks after reading the thread about how many of these mowers are catching fire. i'm already pretty diligent about keeping it free of debris. kind of a pain but the only way to truly clean the mower deck is to remove the belt covers.

If you are under warranty, open a case. Keep repair orders in order and make sure they are written so that they reflect fuel consumption and emissions concerns. Make sure the dealer responds to each concern, even if it is a cannot duplicate etc. Enough squeek will get the service manager at the Kohler Distributor for your district involved. Use their OEM air filters and keep those reciepts. https://kohlerpower.com/en/engines/contact-us

"and of course it is exactly one month out of warranty."