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 |