if your under half throttle your really between the pilot and the needle.... crisp throttle response is not the all end goal.. making your motor LIVE is the all end goal.. a lean motor will have slightly more crisp throttle response, but it also will pop and backfire... WOHOOO... at low speeds your engine is heavily depending on the pilot jet and needle. drop a clip, raise the needle, give your engine some fuel... go up a 2 sizes on your pilot if your using a stock 400 ex pilot... remember having a slightly fat pilot is not a bad thing... I always jet alittle fat on pilots, low speed on any engine is the most stressful time for that motor, you do not have sufficient air to cool the radiator or the cylinder cooling fins... and air cooled motors always run HOT.. its their down fall. i bet you if you go up a size or two on your pilot and stick your clip dead middle, you will have better throttle response then you do now.
86 ATC 500R the duner..
85 ATC 500R...the not quite finished faster duner
1985 ATC 250R Bone stock!!
1985 ATC250R mx/duner
1986 TRX370R MX/Duner
94 Banshee 400PV Cheetah 105RWHP