When I happily turned my WR426 to YZ timing I also bought the original (and expensive) YZ426 needle which was recommended to me by someone on this side. Great, my WR426 was always the fastest. Now I have a WR450F 2004 and consider swapping to YZ timing. I am about to sell my 426 but am wandering if I should swap the YZ426 needle for the WR450 needle. Are the YZ carb needles for the 426 and the 450 the same?