I use the ultrasonic cleaner filled with wd40, run it with heat 2 cycles, then blow it dry and lube with triflo. The chain comes off the kart after every race along with the axle, motor, front hubs, body etc for a bath.As others have said, throw that chain out and get a new one, they're cheap. As for cleaning in the future, some remove the chain and soak it in 'insert oil/solvent/cleaner here'. Some use ultrasonic cleaners or old slow cookers as well. I personally leave the chain on the kart, hit it with some brake cleaner and maybe a brush, blow it dry then lube it with whatever chain lube is closest.