emulsion tubes?

[Sooty]

Just a quick question.
Does anybody know what the diameter of the emulsion tubes are at the point of where the needle goes in? The reason for asking is that my bike is suffering from the usual problem of running rich at tick over. Rather than having to pay for a Factory Pro nickel plated set I was looking at the possibility of sleeving the tubes with a short length of stainless and drilling out to the correct diameter. I'm lucky enough to have access to a lathe with a helpful engineers suppliers a couple of hundred yards from where I live.

[Camala_Pillion]

Sooty,
I am not George but I have worked with him on bikes for 30+ years now. I always got the impression that the emulsion jet did not have a straight bore but was slightly tapered rather less than the needles but just enough to help fuel atomization (not sure that is the right word for the process)

I also remember George mentioning a fellow called STIG on this board who ran the FZR1000 uk board who got emulsion tubes made out of something more wear resistant titanium <?????>


I will ask George when I see him later if he is up to it, mean while search the past posts its here somewhere and being computer useless, as George would say, I cannot give you a link just a hint. :-}

[97fzrnoob]

I just went through replacing mine and I ordered the factory ones from BikeBandit. It ran me 70 bux for all four with shipping and I recieved them in 4 days. I looked at the factory pro ones and bout fell out of my chair at the price plus shipping.

[ragedigital]

I looked at the factory pro ones and bout fell out of my chair at the price plus shipping.

The FP tubes are nickel-plated and are supposed to hold up longer than the brass OEM pieces. That is why the cost difference.

[Sooty]

Your lucky in the States as the FZR ran for a lot longer than here in the UK. Prices for spares are also a lot cheaper but kills any price advantage when they come through customs at this end, 20% tax and a handling charge. Emulsion tubes from European supplier are 38.50 Euro's (£30 or $49.00) apiece + shipping, probably get a slightly better price shopping around but for a full set I'd better inform my bank manager! No good looking at second hand as they are likely to be more worn than the set already in.
What I thought I could maybe do was either get some small round stainless or a seamless stainless tube with a bore smaller than the finished size, drill the emulsion tubes out to a depth of 3 or 4mm to take the stainless and silver solder it in place. I could then machine the top to match the original height and drill them back out to the correct diameter. Anybody got any thoughts on whether this would be successful?

[reelrazor]

I am pretty sure the emulsion tubes are cross drilled through the needle passage. The size of those cross drilled holes has a big effect on how the emulsion tubes function

[yamaha_george]

Your lucky in the States as the FZR ran for a lot longer than here in the UK. Prices for spares are also a lot cheaper but kills any price advantage when they come through customs at this end, 20% tax and a handling charge. Emulsion tubes from European supplier are 38.50 Euro's (£30 or $49.00) apiece + shipping, probably get a slightly better price shopping around but for a full set I'd better inform my bank manager! No good looking at second hand as they are likely to be more worn than the set already in.
What I thought I could maybe do was either get some small round stainless or a seamless stainless tube with a bore smaller than the finished size, drill the emulsion tubes out to a depth of 3 or 4mm to take the stainless and silver solder it in place. I could then machine the top to match the original height and drill them back out to the correct diameter. Anybody got any thoughts on whether this would be successful?

Sooty,
Did you check STIG for his source ?

[DonTZ125]

I am pretty sure the emulsion tubes are cross drilled through the needle passage. The size of those cross drilled holes has a big effect on how the emulsion tubes function

absolutely. 4-strokes have 'emulsion tubes' with lots of holes, while 2-strokes have needle jets or main nozzles with no holes.

[ragedigital]

[Sooty]

I have been able to obtain a brand new genuine Yamaha emulsion tube part No. 3EN-14141-90. Measuring the length internal against external it is only the top 5mm that has the restriction for the needle to effect the fuel flow. I would therefore only have to sleeve the top 5mm of the tube to return it back to the original diameter and this would not effect the cross drilling further down the tube. I can obtain some 3.3mm OD seamless stainless steel with a 0.50mm wall, the diameter I'm getting with my vernier on the new tube is 2.75mm for the bore (will confirm this when measured more accurately). These are standard drill bit sizes and are easy to obtain and although nobody seems to have attempted before on the forum it would seem to me to be a relatively simple job. The alternative is to pay a small fortune to Racing Pro for their nickel plated tubes or end up with the same problem I have now with in a few thousand miles with the plain brass.

[DonTZ125]

Sooty - check that bore carefully. Is it cylindrical? Tapered? Double-tapered (wasp-waist, in then out again)?

[yamaha_george]

S,
drills CANNOT be used for this job, they are simply NOT round enough or capable of giving the correct diameter.
If you were to drill a hole it is not round but usually tri-lobed, you must drill undersized then ream it out to size with at least a five flute reamer. The hassle is this must be done when the insert is in situ or the act of insertion will deform the bore.

Please do not take this as a put down just that you need to be aware of the "crudity" of what we humans use as tooling. If you have access to a good lathe and tooling I would suggest making ago/no-go guage to be sure of that bore measurement.

remember that you are dealing with volumetric flow NOT a pure diameter, each part of decimal point wrong in diameter is what ? magnified by square multiplied by the length of tube.

just thinking out loud how about using a Spark erosion device, now they are accurateso much so that I saw a complex hole cut in 12 thick material and at first I thought it was incomplete as the "core" did NOT drop out but had to be pushed out. When re-inserted it took nearly a minute to sink thro under its own weight.

Question did any one get hold of STIG for his source?

[Racing]

George is 100% correct.
Having worked on carbs most of my life there is no such thing as drilling an emulsion tube or mainjet in my book.
It takes reamers. Simple as that.

These can be had though and if you get a hold of a correct one without breaking the bank it might still be an idea to make this into a DIY project.

[dru86]

I guess you guys haven't heard of jet drills then? This is what alot of engine shops use to open jets up.

The proper way would be to drill the emulsion tube, insert the new sleeve and then bore to size on a lathe with a mini boring bar (a boring bar produces a more precise hole than a reamer).

[yamaha_george]

I guess you guys haven't heard of jet drills then? This is what alot of engine shops use to open jets up.

The proper way would be to drill the emulsion tube, insert the new sleeve and then bore to size on a lathe with a mini boring bar (a boring bar produces a more precise hole than a reamer).

Dru,
Enlighten us please, what is so special about a jet drill

Whilst boring bars do produce a more "round" hole I have never seen one that did holes under 1/4" in commercial work, Technology does move on so if you can point us to where you have seen this I for one would be grateful.