70% of damaged key ways are caused by the keys not being installed correctly. 25% because the flywheel was not properly lapped or torqued and the remaining 5% is because foreign material interrupted the mate (not cleaned). The key should run parallel to the shaft not the taper. If the key is higher on the engine side it will not allow the flywheel and crank tapers to mate properly, it should not stick up at all on the engine side of the taper. The key should be higher on the thread side of the shaft. This is the whole reason why we do not run keys, its only job is to hold the flywheel in place so the wheel and crank tapers mate up while being torqued. The key does not nor will not hold the flywheel from spinning, that is the tapers job. Lap the wheel using a medium compound, clean the wheel and shaft very well and torque to a minimum of 60 ft/lbs. Some use 80 to 90 ft/lbs. True SFI will not make your kart faster, but ABS brakes, air bags nor seat belts make your car faster either. It just gives you piece of mind.