My front pulley nut came loose twice while riding. Trust me it's not pretty, both times the mainshaft machined the teeth right off the rotor, and the second time the flywheel pulled the mainshaft and timkin into the motor almost 1/4". Since then I put locktite and I safety wire it in place. I've had that thing off at least 10 times in the last year, never a problem if you heat it with a torch. If it comes loose, you've got a catastrophe. With the open primary you got that big heavy pulley spinning way out there, more stress and more torque against that nut when you hit the gas.