I have a Case 222 lawn tractor I bought in 1983 brand new. It has the Kohler 12 HP motor. My problem is after I mow for about 15 minutes it will start bogging down and then die. You can start it right back up again and after a few minutes it does the same thing. I've took it to 2 different mower places and this is what has been done and nothing has fixed it. New carb installed New coil New condensor New points (and adjusted properly) New gas cap (thinking clogged vent line) Adjusted timing New spark plug I'm at a loss and so are the shops that have worked on it. I've yet to take it to a Case dealer, I did call one and told them everything it was doing and everything that has been replaced and he said it could be something in the motor, possibly a valve issue. It's definitely heat related, but once it starts having this problem, it takes only a minute or 2 to do it again. It also seems to run better when the mower is not engaged, so if there is a load on the mower, it's alot worse. I've got a schematic of the electrical and I noticed there is a solenoid, rectifier and an alternator. Could either of these electrical components be causing this? Does anyone think it's actually in the head of the motor causing this? When it starts to die, I can quickly disengage the mower, throw the choke on and sometimes that prevents it from dying, but not always. The fuel has been dumped, tank's been cleaned, new fuel line installed, etc. I'm at a loss!!