bhai ur engine needs a ballnced supply of air/fuel not a supply rich with fuel or air..
the purpose of needle is mis understood.. it is not there to allow u to get performance from ur bike.. it is there to compensate for the improper mixture arising form overly used /old carb.. when ur carb is used alot the main jets slit becomes enlarged thus allowing more fuel by adjusting the needle u can reduce the overly rich mixture.. and hence optimize the burn ..
the needle is also there when u go high on elevation to lean the mixture as there more air is needed to combine with the fuel .. so at high altiutdes the erstwhile proper mixture turns rich.. so with the needle u can lean it..
and any fiddling with needle will only be effective from 3/4th to full throttle opening ..
as i mentioned in previous post hte proper mating of pipes is esential .. without proper mounting u r restricting the holes thus reducing the air flow thus performance..
also check if the slide is fully up in the venturi of carb when at full throttle ... if u r not getting full top speed..