What Drill size Makes 140 Jets?

Anyone?

There is no standard drill size the 140 designates 140cc/Min flow. It is determined by the hole size + length of hole + taper angle at both ends. There might be something close in size but close might +/- 10cc of flow.

Drilling is complete guesswork. Your just drilling, not making a different correct jet size.

Dynajet, Mikunki, and Keihin jet numbers all mean different things too...

If you want 140's you have to buy them, or else drill and chance it.

GL.

Okay thanks for the reply.Im gonna try and drill a set of 115s That I have.I'll see if I can shape the hole.Just some thing I wanna play with.What size drillbit fits in a 140 jet on a set of BSs?
Im gonna try and shape the jet like a small velocity stack.And try some other shape profiles.Just wanna know the diameter of a 140 jet.Seems to be the optimum size for a liter size Kawi.Im just throwing around some ideas cause its pouring rain here and dont wanna ride in it.
Thanks in advance Jeff

















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It would fall between a #53 and a #54 drill bit. That will put you between a 130 and a 160 jet size

Thanks Otto!

Use the #54 drill. Unless you are using a precision piece of equipment, like a mill, and a good quality drill bit then your drill will cut oversize.

If you MUST drill than start out with a #54 drill bit and see what it dose. Before you go to the #53 drill. I would even start out with a #55 IF I HAD TO. But when 4 jets cost $7, why would I the two drill bits will cost just as much. This subject must have been covered a half dozen times in as many months here.

Doing the drilling on a lathe.Playing with shape profiles with a tiny little file and my bare hands.Thanks for the call on oversize.I knew that.Every drillbit cuts a bigger hole then its indicated size.Why is that?Maybe some thing happens with tool deflection during the cutting?

Before anyone gets all flussdered at me I just wanna say that my bikes are toys and I like playing with my toys.You never know until you try EH.

jeffasaki wrote:

Doing the drilling on a lathe.Playing with shape profiles with a tiny little file and my bare hands.Thanks for the call on oversize.I knew that.Every drillbit cuts a bigger hole then its indicated size.Why is that?Maybe some thing happens with tool deflection during the cutting?

Lots of factors play into it. First are the cutting angles on the drill need to be exactly the same for the drill to remain on center and cut to size. Next the relief angle on the cutting edges needs to be the exact same. Also the lengths of the two cutting edges need to be the same. Also since you are using a lathe, you need to make sure that your tailstock is exactly on the centerline of the part in the chuck. Finally you need to make sure that the axis of the drill is aligned axially with the centerline of the drilled hole. Of course none of these factors will ever be perfect, so you come out a little oversize. Mostly you will find that your hole is slightly bell mouthed.

Btw you can experiment all you want, but it is very unlikley that you will be able to repeat your profile even one time by doing it by hand with a file. This would be fine on a single carb bike, but will lead to mucho headaches since you are trying to get four carbs to do the exact same thing.

I almost forgot, you are right about the tool deflection. If you don't get the surface footage (rpm) and feed rate (the rate that you advance the drill into the part) right, then you can deflect the tool. It is more critical on the smaller drills. You can haul ass with a 3" inserted drill, but don't try it with a #54. Recomended surface footage for brass is 200 sfpm with a high speed steel drill. To achieve 200 sfpm with a #54 drill, you would need 13,800 rpm. Recomended feed rate is 0.001"/revolution, so 28 in/min. But if you have drilled with the lathe, then you can feel when it is cutting well.

I'm not trying to bust your balls, I just do this for a living and I want you to know what you are getting yourself into. At the very least, in order to learn anything from your experiment, then you need 4 jets that are exactly the same. Otherwise, you are dealing with unending tuning issues. Even if you get four exact same jets then you need to make dyno pulls to verify your results. I think that Otakar is right here. You can't beat Z1E's price on jets. I'm a machinist who runs the machine that these jets are made on, and it isn't worth my time to make my own jets.

Thank you very much!Testarossa!For a free lesson in turning,It takes me about 5 min to swap my carbs and take it for a blast down the highway.I know your not trying to bust my balls.And the turning info is much appreciated.However Im gonna play around Cause thats what I like to do.Ive got 6 sets of carbs that will mount on my green bike.The next ones Im gonna try are a set of keihn 36mm CVs they came off a 92 ZX600 they have tilted float bowls and dont know if theyll work but Im gonna try.Its all fun and games for me and I usually seem to learn the hard way anyways.Thanks again for the turning info.
PS I get drill bits free at the shop I used to work at and have access to a good mill,lathe and a lapping table.
I'll let you all know what conculsions I come to