Been there, done that. Fortunately our engine guru was also a sponsor

My favorite was running the Yamaha in practice at a little asphalt road course. About a half a second before standing on the brake for the hairpin at the end of the straight, the crank broke and the clutch beat me into the first turn. Damn near took a guys ankle off as it went under the fence. Fortunately our engine guys shop was just down the street so he got it rebuilt in time for the race.

After winning my race, we had to pull it out of my kart and drop in another guy's that seized his up. He went on to win his race with it too.