User blog comment:LittlePeng9/Random Turing machines/@comment-1605058-20130411200122

I know this bound isn't very impressive, but I found out my Kirby-Paris hydra machine can be simulated using 2 colors with at most 540 states. More generally, if n=ceil(log_2(c)) (c is number of colors) we can simulate it on 2-color machine in at most (2^(n+1)-1)*2n*s. Anyone interested in construction please ask