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Dyno'd my YZ450F- questions on adjusting jetting/ A/F ratio

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I put my YZ450F on the dyno after building this years race engine, and picked up 2.2hp from the jetting i went in there with to what I left with. But, wanting the jetting to be the best possible, I have a few questions. We did all the runs in 4th gear WOT runs through the gear. We kept going up on the main jet and went from a 175 to 185 main jet and richened the needle one groove from my previous setting and achieved the highest peak hp setting and broadest power, but looking at my air/fuel reading I could use to richen the mixture between 7k and 9k rpms where it jumps up to 12.8:1 vs the rest of the curve that tested best HP at 12.0:1. Being that the throttle is already at WOT during that RPM range, how would one go ahead and richen that spread? Is it correct to do dyno runs at WOT thru one gear? My bike is raced flattrack and only see's one gear around the track and typically is wide open most of the time down the straights. I looked but could not find any other examples of dyno charts to see the A/F ratio curves for bike similar to mine to compare. It seems to me that once the throttle is already clocked wide open that a needle adjustment is going to be very minimal on its effects, and maybe the vacuum the engine is pulling as rpms rise is giving the lean spot? Any input would be appreciated, this is my first time dyno tuning my bike and it was amazing to gain the 2.2hp we already got. Thank in advance!

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