Topic: Jet size vs drill size

[mdart]

I've seen alot of discussion about what drill size equals what jet size.
In my CB400F I have .75mm main jets, that equals .0295 in. The closest drill size to that is a # 69 at .0292 in. If I want to increase the jet to an .80mm (.0315 in) I will use a 1/32 drill at .0312 in.
If you want to cross reference jet sizes and drill sizes, find a drill chart online. Most drill manufacturers give out poster size charts to machine shops. Common drill charts list everything from a .0059 in. diameter which is a # 97 drill up to .500 in.
They show all fractional, metric, letter, and wire gauge sizes.
Once you look at one of these charts you'll know what the closest drill size is to whatever jet size you want. You'll also notice that you can use drill sizes in between common jet size.

[333]

One thing mentioned in a recent thread is that when using a twist bit, the hole it makes is ever so slightly larger than the bit size.  It also seems to me that it's a fair amount of work for jets that are readily available and not terribly expensive.

[TwoTired]

Precision holes are reamed to size, instead of simply drilled.  Standard twist drills make holes that aren't very round and the resulting hole is larger than their measured size.

Jet reamers and jet sizing gauges are available.