JETS-R-US: CARB SWAPPING CONVERSION
AND
CONVERSION FOR KEIHIN TO MIKUNI TO DYNOJET

Question, I am swapping a Keihin carb for a Mikuni carb, what jet do I use? The table below may give a place to start. For example lets suppose that a Mikuni carburetor has a size 100 main jet in it, the equivalent Keihin jet would be a 110. Therefore after the carb swap a "guesstimate" to start with would be a keihin 110 jet. The chart will not be a perfect match because there are many variables, for example, different carb flow characteristics, different needles, orifices etc. but it is a starting point.

Question, I have some dynojets and would like to purchase Jets R Us jets, how do I compare the sizes? We do not sell dynojets. Dynojets as well as many other aftermarket jet manufacturers try to duplicate the original jets but there are variations. A simple example is dynojet does not produce hex jets, only round and therefore dynojet provides a main jet adapter. Because dynojets are not manufactured 100% the same as mikuni and keihin there is not an exact comparison between the two.

Question, how is the table below used?
Example: 1) I bought a used motor with Keihin carburetor that has a dynojet 100 in it. The Keihin equivalent would be a 102.
Example 2) I bought a used motor with Mikuni carburetor that has a dynojet 112 in it. The Mikuni equivalent would be a 105.

Note that Keihin jets cannot be placed in Mikuni carbs and vice versa.

The table below is an approximation, results in the carburetor will vary.

KEIHIN DYNOJET MIKUNI
92 92 85
95 94 87.5
98 96 90
100 98 92.5
102 100  
105 102 95
108 104 97.5
110 106 100
112 108  
115 110 102.5
118 112 105
120 114 107.5
122 116  
125 118 110
128 120 112.5
130 122 115
132 124  
135 126 117.5
138 128 120
140 130 122.5
142 132  
145 134 125
148 136 127.5
150 138 130
152 140  
155 142 132.5
158 144 135
160 146 137.5
162 148  
165 150 140
168 152 142.5
170 154 145
172 156  
175 158 147.5
178 160 150
180 162 152.5
182 164  
185 166 155
188 168 157.5
190 170 160
192 172  
195 174 162.5
198 176 165
200 178 167.5
202 180  
205 182 170
208 184 172.5
210 186 175
212 188  
215 190 177.5
218 192 180
220 194 182.5
222 196  
225 198 185
228 200 187.5