emulsion tubes?

[dru86]

I've no idea why they're so special but it's what a lot of places use to modify jets, guess that why they're called jet drills . Just google jet drill I'm sure you'll find plenty of references to them, crap loads for sale on eBay.

Google is you friend here again for the bars. Found this one min it will do is 2.2mm http://www.directindustry.com/prod/mits ... 59820.html. Another option would be to grind your own from either HSS or carbide. Anyone who does any serious lathe work will have ground their own tools at some point.

[ragedigital]

All of the jet drill bits I have seen (i.e. LINK) are usually carbide micro drill bits and I would imagine are reserved only for Main Jets, etc.

For the time, tooling and wasted material involved in making/fixing your own, you're probably better off working a couple hours of overtime and getting the FP emulsion tubes and not worrying about the inserts falling out, collapsing, differences in machining, etc.

[reelrazor]

For the time, tooling and wasted material involved in making/fixing your own, you're probably better off working a couple hours of overtime and getting the FP emulsion tubes and not worrying about the inserts falling out, collapsing, differences in machining, etc.

That's kinda my thinking:

Yeah, they're pricey, but what is MY 'free time' worth?

And, in my case, it's worth a hell of a lot. So, I buy many things that I could make for 'free'.

[yamaha_george]

I've no idea why they're so special but it's what a lot of places use to modify jets, guess that why they're called jet drills . Just google jet drill I'm sure you'll find plenty of references to them, crap loads for sale on eBay.

Google is you friend here again for the bars. Found this one min it will do is 2.2mm http://www.directindustry.com/prod/mits ... 59820.html. Another option would be to grind your own from either HSS or carbide. Anyone who does any serious lathe work will have ground their own tools at some point.

Dru,
Sorry to say that what you are talking about is a basic drill bit with its flawed cutting of "round" holes ability, in the engineering business they are just plain (as in ordinary) NUMBER series drill bits. The fact that they have apparently been given the title "jet drills" is a piece of marketing speak to imply that they are some how special they are not they are just small but still do not actually cut a "round" hole any better than their big brothers.

I took a look at the boring bar again nothing special just small. The hassle of such small bars is the bit behind the cutting tip flexing the longer the holder the worse the problem of tooling marks becomes and thus the problem of de-laminated flow thro the jet. you would still have to some how (ream / polish ?) the marks off and to extremely tight tolerances.

The latter by the way are NOT practiced in the Jet making industry see: -

http://www.saltmine.org.uk/martin/jet_sizing.html

[dru86]

No where did a say that i would use the jet drills on the emulsion tubes. I was referring to the comment that racing made about not drilling main jets, as you posted in your link hole shape is irreverent to a main jet, its the flow. What i said was to bore the emulsion tubes. The boring bar only has to go in 5mm, flex would not be an issue.

If i did have to do the emulsion tubes I'm guessing it would take me ~1hr. Considering I've already got all the stuff on hand and the tubes cost $160 with post, that's not a bad hours work(no tax either).

[yamaha_george]

No where did a say that i would use the jet drills on the emulsion tubes. I was referring to the comment that racing made about not drilling main jets, as you posted in your link hole shape is irreverent to a main jet, its the flow. What i said was to bore the emulsion tubes. The boring bar only has to go in 5mm, flex would not be an issue.

If i did have to do the emulsion tubes I'm guessing it would take me ~1hr. Considering I've already got all the stuff on hand and the tubes cost $160 with post, that's not a bad hours work(no tax either).

Dru,
I did not imply that you said to drill any thing, I meerly pointed out that drilling to get around hole is flawed and went on to point out that flawed or not drilling main jets is fine since flow is the criteria and pointed to a study done on commercially available jets where the sizing stamped on the jet was almost meaningless.

Those of the group who take tuning SERIOUSLY now know that so called "identical" numbered can vary by quite a lot.
& can now test them individually themselves if needed.

Going back to the emulsion tubes you would turn the outer diameter, pilot drill the bore presumably and then "clean" up to size a 5mm length with the boring bar ? As you say not bad for an hours work in the shed <BG> and have the satisfaction of knowing that you made it , which is always a big grin for me.