i have run them since 2006, and even with over 100hrs on sets, havent seen them flap. i wouldnt hesitate to run them on any new machine i got.. i tried the v4 on a 250 ktm and had jetting issues. i started swapping back and forth between the v3 and v4 and convinced myself i just didnt like the new v4 design. big fan of the v3 though.