This is a special crankshaft for a Kohler K Series single cylinder engine as used in a lawn tractor like a Cub Cadet. These engines are easily modified for more power and are used in lawn tractor competition (no joke) like tractor pulls and racing. The maker of yours is unknown but there are a few suppliers that sell these forged crankshafts. I've supplied a URL to one company that specializes in performance parts for these engines. He sells a crankshaft very similar to yours. There are many more suppliers.

This is a special crankshaft for a Kohler K Series single cylinder engine as used in a lawn tractor like a Cub Cadet. These engines are easily modified for more power and are used in lawn tractor competition (no joke) like tractor pulls and racing. The maker of yours is unknown but there are a few suppliers that sell these forged crankshafts. I've supplied a URL to one company that specializes in performance parts for these engines. He sells a crankshaft very similar to yours. There are many more suppliers.

References:

https://mwsc.co/collections/k-series-engine-parts/products/forged-crank