Hi, I am in the process of making a 2006 R6 4 pot radial mount caliper fit on the front of my 02 YZ426. I bought a 320mm motomaster rotor and the R6 master cylinder and caliper. I can tell you that it will work, but from what I have found the front rotor needs to be spaced out .5 in. The spacer needs to be a machined ring, not just long bolts with washers. I will document the process and post pictures and the Solidworks drawings of the adapters that I make under my "how to/ show and tell" thread. It is under this section, called 02 YZ 426 Conversion. What I have been able to find is that there is not a way to do it without machining your own parts. Hope this helps.