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A short tutorial on replacing the keihin PWK emulsion tube

Darryl, thank you! I'll likely press the tube into place. I'm not a fan of hammering on small aluminum parts, especially when they are not readily available. billie

One comment, this is actually more properly called a needle jet. An emulsion tube serves a bit different purpose and is located in basically the same location of the carburetor, but the emulsion tube has a lot of small holes drilled around it in the middle section. The emulsion tube is also typically a combination part that includes the main jet receiving threads. Sometimes the emulsion tube is also the needle jet as well as the main jet holder.

Chuck78 wrote: 07:50 pm Dec 26 2025 One comment, this is actually more properly called a needle jet. An emulsion tube serves a bit different purpose and is located in basically the same location of the carburetor, but the emulsion tube has a lot of small holes drilled around it in the middle section. The emulsion tube is also typically a combination part that includes the main jet receiving threads. Sometimes the emulsion tube is also the needle jet as well as the main jet holder.

Agreed but I've found needle jet and jet needle get confused and the average person seems to call them emulsion tube so I just went with that vocabulary
Keihin CV 26mm has the last that you stated,a combined emulsion tube and needle jet, the keihin PE from Japan has no emulsion tube but the PWK 28 and Thai made keihin pe28 have an emulsion tube and separate needle jet although they don't share the same emulsion tube

Its JD in Texas, got your tube installed today and it instantly required less idle screw, was all the way in before and barely idling and smoking heavily, with gobs of spooge. After tuning the carb, the idle screw is way out from where it was and adjustment is very responsive. Initial warm up riding has the throttle MUCH snappier and tons more power than before. I still need to verify further jet changing back the other way isn't required (currently 142m, 38 pilot middle clip, R1174 needle.) since I've been chasing the rich condition with no luck til now. Thanks for sharing and thanks for offering the part.

That's great news, glad it fixed your problem, it takes time to get a bike dialed in perfectly but at the very minimum we want a usable bike, 9 years ago when I bought my first kdx220 it was unusable and the same thing, idle screw turned all the way in just to get an idle, previous owner gave up on it as did all the previous mechanics
How on earth did this emulsion tube thing go unnoticed/unsolvable for the last 25 years

I meant to thank you for the video when I originally saw this post.. So THANK YOU! It seems relatively simple, and even though I am running a Lectron full time now, I may do this to the 2 extra PWK35's I have, assuming that the needle jet/emulsion tube is the same size.. You said this is off of a 220, so that means the carb is a PWK33 if I remember correctly.
One question, did you make the part yourself/get some machined for you? Or can you buy them somewhere online? Scratch that, I found your post on TT. I'll be in touch!

Thanks!!

SpruceItUp wrote: 10:58 pm Jan 23 2026 I meant to thank you for the video when I originally saw this post.. So THANK YOU! It seems relatively simple, and even though I am running a Lectron full time now, I may do this to the 2 extra PWK35's I have, assuming that the needle jet/emulsion tube is the same size.. You said this is off of a 220, so that means the carb is a PWK33 if I remember correctly.
One question, did you make the part yourself/get some machined for you? Or can you buy them somewhere online? Scratch that, I found your post on TT. I'll be in touch!

Thanks!!

Stay tuned, I have a lectron tuning video I will do next week

Darryl, are you able to ship to the USA yet/again, by chance?

Also, I'm just curious what the exact i.d. of the needle jet orifice in the emulsion tube was? I'm quite sold on the newest generations of Lectrons ( the Billetron Pro Series Xcelerator & even the new billet version of the H-Series Lectron) as well as the more affordable but more difficult to tune SmartCarb SC3 34mm that's basically ready for release any day now for the 200H & 220R.

It'd be nice to see what it'd take to DIY machine one and finish hone with emory cloth perhaps, if a drill bit finish was not enough.

Chuck78 wrote: 01:45 pm Jan 24 2026 Darryl, are you able to ship to the USA yet/again, by chance?

Also, I'm just curious what the exact i.d. of the needle jet orifice in the emulsion tube was? I'm quite sold on the newest generations of Lectrons ( the Billetron Pro Series Xcelerator & even the new billet version of the H-Series Lectron) as well as the more affordable but more difficult to tune SmartCarb SC3 34mm that's basically ready for release any day now for the 200H & 220R.

It'd be nice to see what it'd take to DIY machine one and finish hone with emory cloth perhaps, if a drill bit finish was not enough.

I have the new Billetron Pro Series Xcelerator (or just Pro Series? I'm unsure) Lectron in my E series, and while it is easy to make adjustments, the stock settings they ship it with were WAY off. I went through several Xcelerator rods (covered by Lectron) finding the proper one for the bike. I ended up at a X3-3 rod for my bike. I can't remember the one it shipped with, but I still have it and I'll provide it eventually. It took me several months to get tuned (some due to my part as it burned me out like crazy after dealing with the Lectron and getting the same results each time). It runs like a top now, though. Thankfully Lectron support was extremely helpful and were willing to send the rods for free (they're about $90 a piece on their own).
Blah blah blah.. this isn't the thread to discuss this.. but I get carried away. I've been meaning to make a thread reviewing it, but I just haven't had time to do so yet.

I'll be sure to check out your Lectron post, Darryl. Thanks!