Found this on another site, thought it was worth preserving:
Width------Keihin # -- DynoJet # -- Mikuni #
0,0350---- 92,5--------- 92----------- 86,3
0,0360---- 95----------- 94----------- 88,1
0,0370---- 97,5--------- 96----------- 90,0
0,0380---- 100---------- 98----------- 91,9
0,0390---- 102,5------- 100---------- 93,8
0,0400---- 105--------- 102---------- 95,6
0,0410---- 107,5------- 104---------- 97,5
0,0420---- 110--------- 106---------- 99,4
0,0430---- 112,5------- 108--------- 101,3
0,0440---- 115--------- 110--------- 103,1
0,0450---- 117,5------- 112--------- 105,0
0,0460---- 120--------- 114--------- 106,9
0,0470---- 122,5------- 116--------- 108,8
0,0480---- 125--------- 118--------- 110,6
0,0490---- 127,5------- 120--------- 112,5
0,0500---- 130--------- 122--------- 114,4
0,0510---- 132,5------- 124--------- 116,3
0,0520---- 135--------- 126--------- 118,1
0,0530---- 137,5------- 128--------- 120,0
0,0540---- 140--------- 130--------- 121,9
0,0550---- 142,5------- 132--------- 123,8
0,0560---- 145--------- 134--------- 125,6
0,0570---- 147,5------- 136--------- 127,5
0,0580---- 150--------- 138--------- 129,4
0,0590---- 152,5------- 140--------- 131,3
0,0600---- 155--------- 142--------- 133,1
0,0610---- 157,5------- 144--------- 135,0
0,0620---- 160--------- 146--------- 136,9
0,0630---- 162,5------- 148--------- 138,8
0,0640---- 165--------- 150--------- 140,6
0,0650---- 167,5------- 152--------- 142,5
0,0660---- 170--------- 154--------- 144,4
0,0670---- 172,5------- 156--------- 146,3
0,0680---- 175--------- 158--------- 148,1
0,0690---- 177,5------- 160--------- 150,0
0,0700---- 180--------- 162--------- 151,9
0,0710---- 182,5------- 164--------- 153,8
0,0720---- 185--------- 166--------- 155,6
0,0730---- 187,5------- 168--------- 157,5
0,0740---- 190--------- 170--------- 159,4
0,0750---- 192,5------- 172--------- 161,3
0,0760---- 195--------- 174--------- 163,1
0,0770---- 197,5------- 176--------- 165,0
0,0780---- 200--------- 178--------- 166,9
0,0790---- 202,5------- 180--------- 168,8
0,0800---- 205--------- 182--------- 170,6
0,0810---- 207,5------- 184--------- 172,5
0,0820---- 210--------- 186--------- 174,4
0,0830---- 212,5------- 188--------- 176,3
0,0840---- 215--------- 190--------- 178,1
0,0850---- 217,5------- 192--------- 180,0
0,0860---- 220--------- 194--------- 181,9
0,0870---- 222,5------- 196--------- 183,7
0,0880---- 225--------- 198--------- 185,6
0,0890---- 227,5------- 200--------- 187,5
Some illuminating comments from a pro:
Keihin "393" series:
The Keihin sizing is pretty close to right (ish). Close enough for hand drilling a jet when you don't have what you need. A 150 is 1.50mm in diameter.
Factory Pro "393 K Series":
The Factory Pro "K Series" jets are also dimensionally sized, just like the Keihin jets.
Example: a "150" Keihin or "K Series" main jet is usually 1.50mm in diameter.
Dynojet:
According to dynojet,
http://planetminis.com/f21/finally-f...-52984.htmlthe dynojets are supposed to be sized the same as Keihin (dimensionally)- but I've never found that to be true.
As far as different lead-in angles and such, I'm guessing that that difference is more that metric manufactured K and M jets tend to have a std metric 90 degree included lead-in included angle and USA manufactured jets tend to be 82 degree included angle. I could be wrong on the lead-in angle, but I remember that that dj is different. It was 20+ years ago that we started making Keihin and Mikuni style jets.
Mikuni N102221 (small round slotted jets)
That part of the chart is wrong. The gist is right, but, the holes sizes are wrong.
You have to take a selection of jets, across the entire range, measure and create a curve for them to be correct.
Summation -
If you have a pile of a certain brand of jet and you want to use them, it's up to you. I've seen and tuned Keihin carbs jetted with Mikuni jets that "squeak" that last 1/2 turn (the threads are .05mm pitch different) and vice versa. Heck - I've even used dynojet jets if that's what's available.
SO.....If you are using a particular brand of jet, don't swap brands of jets using this dj and Mikuni cross reference chart.
If you are drilling jets (reaming is preferred, btw) then, you'll likely find that a Keihin, dj and Mikuni jet, with the same orifice sizes, flow very similarly.
If you take the decimal inch size and multiply by 25.4, you'll get the metric dimension and the Keihin / Factory Pro jet sizes.
Example: .0390" hole x 25.4mm = .9906mm hole (or essentially a "100" Keihin or Factory Pro "393 K Series" 100 main jet.
Thanks -
Marc Salvisberg
Factory Pro Tuning