Kohler K301
 

My first post but I've had this Cub Cadet 104 for about 20 years, been in the family since new, motor replaced in the 80's.

Recently the carb started leaking gas so I put in a new carburator. When I raised the throttle the motor was running very high so I was adjusting the high mixture screw to lower the rpms and I idled down, then turned off the mower. Now the starter just spins the belt and the motor won't turn over. Did I overheat the motor and lock it up?

The high engine speed leads me to believe that the governor linkage isn't set properly. Don't adjust the high speed jet to obtain your desired rpm, that's not what it's for. Tha'ts the job of the governor. Depending on how long you ran engine maybe you locked it up, but probably not. Can you turn the engine over by hand? I would first check belt tension.

Did you use some cheap chine's carb? I recommend rebuilding the old carb.

Yeah it was a cheap Chinese carb. I'm learning... I can't reach the pulley for the motor very well and cannot get it to turn. The belt is tight but maybe slipping.

I took off the mowing deck but I'm not sure how to take off the starter belt. I can't spin the motor pulley by hand, awkward to get in there with the front PTO clutch.

What should I do next to check the motor?

Here's a video of the starter spinning.
https://youtu.be/yZEdcAa8G8w

Thanks

Video seems to show a seized motor.....not good. It's possible you over heated it or over revved it too lean. Did you check the oil, yet? Might have to pull head for a looksee.

I checked the oil right after I shut it down and there was some, then I checked after it cooled down and none showed on the dipstick. I changed the oil the spring of 2020 and haven't driven it much since because the carb was leaking gas.

Should I pull the motor out or can I pull the head while it's still on the mower?

I wouldn't think you need to pull the engine to pull the cylinder head, Maybe the fuel tank and the heat shield. I only have wide frames and quiet lines at the moment, no narrows.

Maybe drain the oil and check it for debris.

You can pull the head with the engine installed in the tractor, no problem. You'll need to pull the gas tank and some assorted engine shrouds, but it won't take long. If the bolts are being stubborn, don't force it - you don't want to break any.

I'd definitely get hands on the front pulley before taking anything apart.