I know a guy who has a 250 trailboss motor and he said the crank is bad but he says the piston and rings and cylinder should still be good ?? Is this possible for just the crank to go out without effecting the others??

 

did he loose the crank bearings? did the crank twist or something? the piston and cylinders would still be good if he didnt run it out of oil and seize it up. just my opinion.