Drilling out jets, where can I find size chart?

Rather then buying new jets I would like to drill the ones I have. Could someone point me to a chart that shows me what size drill bit equals what size jet? I need a 92 and a 70 jet size and I am not sure I can drill out a pilot jet but if I can I need to know what size drill a 36 jet is.

I don't know if a chart exists since the 'number' on a jet does not mean the same thing between different manufacturers. Keihin jets are numbered different than Mikuni, etc.

A sure fire way to find out is to find someone with a set of gage pins that you can use to measure the diameter fo the hole in your jet. Next, calculate the AREA of the hole of your jet (area=radius^2 * pi (3.14)).

From there, you can calculate the percent increase you desire by dividing the number on the jet you want have with the number of the jet you curently have.

Multiply this number by the area of your current jet, then solve for the diameter that equals that area ((sq. root of (area / pi)) * 2) and you will get the diameter of the jet you want.

Please note: this is just an educated guess, not a verified method of drilling jets!

Jason

By the time you figure out the math, find the drill, drill, not f**k it up, and test it.... you could buy the jets from Z1 for a couple bucks each

The parts I need are all special order and I am not afraid to drill out a jet. it's just a small hole that you enlarge.

Well, it's the best I could do.:laugh:

So find a drill that fits and go one size larger, right..? Use the drill shank as a pin gage, I guess.

OK I can do better.Heres a Mikuni chart. (Tell me you have Mikunis:whistle: )

www.iwt.com.au/MIKUNI.HTM

that is a great find but I have keihins. Thanks for trying though.

that is a great find but I have keihins. Thanks for trying though.

www.dirtrider.net/justkdx/jetneedles.html maybe this will help

Drilled jets are not consistent,ever look
at a drilled hole with a magnifying glass?
You will need to purchase the right sized
reemer,and undersized drill.Then you will
have to mark the jets so you don't mix them
up later.It's easier just to buy the jets
if you can.Or you can go all the way,get a
lathe,some brass,a thread cutting tool....

Tim, You will also need to bevel the hole ends in exactly the same way that Mikuni did to get the correct fuel dispersion. If not, the fuel will come out in a splatter. I believe that drilling jets is a waste of time as you have noted, it can't be done consistently unless you have a drill press and way to secure the jet plus bevel the edge at the correct angle. Not saying it couldn't be done but certainly it isn't all that easy to get right without the correct set up.

like previously mentioned....most jets are cheap, mistakes are not.

Post edited by: arobsum, at: 2007/10/06 13:08