I've got a 2004 John Deere LT160 lawn tractor with the Kohler Commando 16hp engine. Ever since a year after we got it every once in awhile when me or my dad go to start it, it will start hard and blow puffs of black smoke out the exhaust. This only occurs after the tractor has run for awhile and tends to randomly happen. There is no pattern to when it occurs. For example today I stopped and started the engine about 11 times and the smoke only occurred once when i went to start it.

Anyone got any ideas? Someone told me this was normal for Kohler engines.

I don't think it's all that unusual, but I would check the choke just to be sure. Make sure the choke opens all the way and the choke plate is not partially closed (even just a little) or it can get sucked closed. The choke on these engines has a spring and can be adjusted to different settings, underneath the plastic spring housing is a guide that runs on a small pin in the top of the carburetor. Dirt can accumulate in this guide and keep the choke from opening completely. If the choke plate will not open all the way, this will need to be cleaned.

Thanks 30year, I will check it out tomorrow!