If we compare the yz timing and the wr timing in term of gaz need with exactly the same air restriction through the circuit (from air box to pipe). Where, on the throttle and rpm, do the yz need less or more fuel that the wr timing. I'm triing to figure out where I should expect a bigger need is gaz for the yz. thank to James D, I know now how to calculate the diameter of the needle at any point for any needle so I can compare their gaz flow between them. Robin P.S. Especially for high restrictin exhaust, see previous posts!!!