unsatisfied with my 426, what's wrong??

[fourtrax400ex]

i have my 426 for about 2month but im not very satisfied about power compared to my 416 that i have before, i have difficulty to found the right setup to have max of power, it seem to have less mid -top end than my 416, so i think maybe it's the cam, i use the xr cam for now, there surely a better cam thant that, i read that xr cam are better with stock bore thant big bore, wich one give me the best power out of my motor? i have try and try thousand of jetting configuration, i run now a 175 main and 45 pilot with needle lower one notch(i know normally im suppose to raise needle but it bug a 3/4 throttle when i do it) i try also different sort of fuel, i run now 50/50 92 gas pump and avgas(100ll), my mod are listed below, im thinking also that maybe the stock carb cant handle the supplementary flow of fuel/air needed for the 426 or maybe have the head port and polish what do you think?

thanks

[yamaha1470]

TC cams are good

[Wheelie]

Have you tried a 170 or 172 main jet....that might help with upper RPM performance.

A cam would also help, so would a polish and port.