Bikes are now restricted to a mere 186mph from the factory. Before that, they were free to run to top end until they ran out of power or were drag limited. But let's be serious: the ZX-12R won't top out much past 186mph, without a big bump in horsepower, a serious decrease in drag, and a very long run way. So, when you see that "unrestricted" BS, mostly pay no attention to it.