It would mean the crank is balanced heavy. There's never much discussion from the pro's on balance factors, but it's all trade off's to minimize harmonics in the engines designed rpm range. I know when I used to be involved in drag bike engines we used different/heavier balance factors for engines that ran higher rpm ranges then say a street engine. maybe not apples to apples but to give an example, build identical 2 Harley engines with the same use in mind. One balanced @ 50% factor for street and the other %60+/- drag set up. The %50 will idle and perform better in the lower rpms. Put it on the track running to 7k rpms it will come undone. The one balanced at %60 will actually smooth out as the rpms come, make a touch more power, and stay together better.