I recently installed a dynojet kit in my 03 lakota sport. I noticed that the stock jet was a size 148 and the kit came with a max size of 138. After using the dyno jet main I found I was running a little lean. I called dyno jet today and they suggested I put the stock main back in or go up a notch on the needle to the 4th notch. I find it interested that an aftermarket performance kit designed to increase fuel flow into the engine would replace a stock main with one that is substantialy smaller.

 

The dyno jet I put in my kfx 700 and the P650 had smaller mains ... but it also had significally smaller
diameter needles. You have to think in terms of the difference in "gap size" between the neeedle
and jet.... not just the jet size.

 

Stock jets (Kehin), and Dynojet sizes are not the same numbers, see chart below

Kehin/Dynojet Equivalency chart

Kehien Jets -------- DJ Jets

Num / Thou. ------- Num / Thou.
92.5 / 0.035 ------- 92 / 0.035
95 / 0.036 ------- 94 / 0.036
97.5 / 0.037 ------- 96 / 0.037
100 / 0.038 ------- 98 / 0.038
102.5 / 0.039 ------- 100 / 0.039
105 / 0.040 ------- 102 / 0.040
107.5 / 0.041 ------- 104 / 0.041
110 / 0.042 ------- 106 / 0.042
112.5 / 0.043 ------- 108 / 0.043
115 / 0.044 ------- 110 / 0.044
117.5 / 0.045 ------- 112 / 0.045
120 / 0.046 ------- 114 / 0.046
122.5 / 0.047 ------- 116 / 0.047
125 / 0.048 ------- 118 / 0.048
127.5 / 0.049 ------- 120 / 0.049
130 / 0.050 ------- 122 / 0.050
132.5 / 0.051 ------- 124 / 0.051
135 / 0.052 ------- 126 / 0.052
137.5 / 0.053 ------- 128 / 0.053
140 / 0.054 ------- 130 / 0.054
142.5 / 0.055 ------- 132 / 0.055
145 / 0.056 ------- 134 / 0.056
147.5 / 0.057 ------- 136 / 0.057
150 / 0.058 ------- 138 / 0.058
152.5 / 0.059 ------- 140 / 0.059

 

Interesting. I wonder why the dynojet technician I spoke with didn't know that bit of info? By your chart my stock jet is about the same size as the 138DJ jet I got in the kit. I will likely order a couple jet sizes larger from dyno jet to richen the mixture a bit.