yup, if the break in the crank is at an angle an somewhat supported, the break will turn cause it's pressed together and the engine will still run. i had an Artic Cat snowmobile that i ran 250 miles with a broken crank. I noticed it started shaking a little and loosening up bolts. got worse and worse and started burning up the drive belt. limped it back to the hotel on the road. i was stunned when i took it apart, because those motors turn 9000 rpm
it should have grenaded.