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Background,

2010 model
Stock engine has less than 50 hrs. Moderately driven.
Modifications:
Two Brothers exhaust system
Airbox modification
K&N Air filter
Fuel Screw 1 1/4" turns out.
JD kit. Needle was in 4th position, with 170 main jet. Pilot jet is stock. Bike sputters after about 3/4" of full throttle.
Moved needle to 5th position, Kept the jet same 170, Pilot jet stock. Bike starts and accelerates fast BUT as it reaches cruising speeds with steady throttle, it hesitates and kind of stumble as it was starving for fuel or something. as soon as you twist the throttle to accelerate, these symptoms disappears.
Appreciate any tips / help.

im not sure exactly but try going up one main and lower the needle one clip.

saefabri wrote:Background,

2010 model
Stock engine has less than 50 hrs. Moderately driven.
Modifications:
Two Brothers exhaust system
Airbox modification
K&N Air filter
Fuel Screw 1 1/4" turns out.
JD kit. Needle was in 4th position, with 170 main jet. Pilot jet is stock. Bike sputters after about 3/4" of full throttle.
Moved needle to 5th position, Kept the jet same 170, Pilot jet stock. Bike starts and accelerates fast BUT as it reaches cruising speeds with steady throttle, it hesitates and kind of stumble as it was starving for fuel or something. as soon as you twist the throttle to accelerate, these symptoms disappears.
Appreciate any tips / help.

You might be too rich on the main, try going down to a 165 or 162 then try it.
I had the same problem but mine was solved by going back to a 45 pilot ( I was running a 48 ).