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Drilling Jets

Banksy

Well-Known Member
Does any one know what the size of a jet relates to in mm ?
I have lots of small jets 60-90 none of which are any good for my setup, Can I just drill them out to the correct size?

And yes I have a set of precistion drills 0.1mm to 1.6mm in 0.1mm increments

What do you think?
 

The Kehin/OKO/Koso main jets are in MM per size . So you can take a drill index conversion chart which contains the drill designation then its size in MM . The mm size of the drill bit is the equivalent to size main jet Number on the previously listed jets.
 
Another one...

Jet 50 Drill Bit #76
Jet 55 Drill Bit #74 approx.
Jet 60 Drill Bit #73
Jet 65 Drill Bit #71 approx.
Jet 70 Drill Bit #70
Jet 75 Drill Bit #69 approx.
Jet 80 Drill Bit #68
Jet 85 Drill Bit #66 approx.
Jet 90 Drill Bit #65
Jet 95 Drill Bit #63
Jet 100 Drill Bit #61
Jet 105 Drill Bit #59
Jet 110 Drill Bit #57
Jet 120 Drill Bit 3/64 th's
Jet 130 Drill Bit #55
Jet 140 Drill Bit #54
Jet 150 Drill Bit #53
Jet 160 Drill Bit 1/16 th's
Jet 165 Drill Bit #52 approx.
Jet 170 Drill Bit #51
Jet 180 Drill Bit #50
Jet 185 Drill Bit #49
Jet 195 Drill Bit #48
Jet 200 Drill Bit #47
Jet 205 Drill Bit #46
Jet 210 Drill Bit #45
Jet 220 Drill Bit #44
Jet 225 Drill Bit #43
Jet 230 Drill Bit #42
Jet 245 Drill Bit #41
Jet 250 Drill Bit #40
 
Mikuni & Keihin jet numbers refer too CC of fuel passed per min.
The link below shows Jet # and actual size for Mikuni/Keihin.

You have to watchout as some use actual size and some CC flow.

Also it's better to ream the jet that drill as standard 2 flute drill bits will tend to cut oversize or oval in brass jets.8)

Find the jet list at http://rage-composites.co.uk

From the list you will see that drilling jets with a twist drill is so inaccurate you could end up with a 140 jet then you think you've drilled it to be a 100.
It's safer to purchase a jet set from scooter attack or scooter center and alot easier too.
 
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