Emulsion Tubes

[Ticketyman]

Okay, is it possible for a bike "1993 GSXR 1100W" with 28,000klms on it to have elongated emulsion tubes? If so what cause and effects may this make?

[mike-s]

elongated? uhm, i cant see how that would be much of a good thing as the emulsion tube is supposed to stop nearly flush with the bottom edge of the venturi. If it was longer one of three thing would happen.

1) if it was a slight increase, possibly nothing, but unlikely.
2) change the midrange fuelling to a further lean condition. This is due to the way fuel is metered in the midrange, as the needle is exposed the quantity of fuel allowed through increases. If the emulsion tube was 2mm longer for example then the quantity of fuel being permitted for a given air requirement would be much less. Which could (and i suspect would) cause a massive lean condition and the bike to run hot and perform like a dog, assuming it doesn't end up eating a piston because of it.

3) the carb slider may be held open a little more, which may screw low end fuelling as well.

Hence i doubt that there is such a thing as "elongated emulsion tubes" unless they've done the dodgy and gotten emulsion tubes from a different bike and "made them fit".

[Ticketyman]

Elongated may be the wrong term, what I was trying to say was oval or out of round not longer!

[mike-s]

Ohhhh, right! i was wondering why the hell anyone would fit the wrong parts, it just didn't make sense.
Well getting the bike to run at a correct state of tune is going to be a right bastard if you get this happening as no matter what you do, you wont be able to fix the state of tune. First off if you fix the idle by winding it in, you may get close, but you'll never quite get it. Same with the midrange or higher throttle openings, it just won't open up correctly and will always seem bogged up to some degree. You can work around it to a degree, but it's going to be a pain in the arse to live with when $100 or so for the emulsion tubes (and the cost of any gaskets or o rings that need replacing along the way) will fix the problem if you do it yourself, provided you know what you are doing. While you have the carbs apart you might as well strip it down and give it a good once over if you go this far.

The two web pages which i have found a absolute bible when looking at tuning are this and this.

[bonester]

Bloody Mikuni carbs wear the emulsion tubes badly even as early in the life of the bike as you state. Factory Pro (I think) make better longer lasting replacements if you want.

[Gosling1]

.....Okay, is it possible for a bike "1993 GSXR 1100W" with 28,000klms on it to have elongated emulsion tubes? If so what cause and effects may this make?.....

Yes, happens all the time on these bikes.

Its because the needle jet, which slides up and down inside the emulsion tube (or jet needle), bangs its way up and down the tube due to the extremely rapid pressure changes within the carbie throat. The airflow inside the carbie throat is not a steady constant one-way flow. The jet needle is fixed, but the needle jet is not, and so it can, and does, wear out the inside of the jet needle in an oval shape. Once they are worn, they are fucked and have to be replaced. They cause all sorts of fuel problems from overly rich running.

Mind you, this is such not a problem on 70's 2-strokes fitted with Mikuni carbies. Back then, they made stuff that lasts.

Get a DynoJet or Factory Pro kit for your gixxer, and you will never look back.