Got it - well, my idle air screws are in good shape, and I also replaced the 32.5 pilot with brand new this week, so I'm good there. Are your mains 102.5? While I'm at it, I might as well buy new mains while I'm spending the money.

Bummer you don't have the needles or spacers.

yeah, the main jets are marked 102.5

Thanks for checking, man. I appreciate that. If for some reason I can't get a hold of new 102.5 mains I'll snag yours. I plan on keeping the bike so I'll spend the money on it. Until my approval on bandit alley goes through, keep an eye out for a set of carbs being offered up for parts for me. I'd grab the other parts.

Other thing I should ask you about that I read online is the "egging" of the emulsifier tube where the needle smacks it. I've noticed that two of the four show wear. Is that something I can get by without replacing or should I get that taken care of as well?

Seems like with brass, it's just going to happen again.

Other thing I should ask you about that I read online is the "egging" of the emulsifier tube where the needle smacks it. I've noticed that two of the four show wear. Is that something I can get by without replacing or should I get that taken care of as well?

Just curious, what method did you use to determine that you have emulsion tube wear? I don't doubt that you could indeed have some wear but I'm kinda surprised, didn't you say your B4 only has 3,800 miles showing?

But yes, the emulsion tube wear phenomena is real and to my mind it's one of the biggest flaws in the whole Mikuni carb design. Although I don't lay the blame completely on Mikuni because there are other forces at work and one of them is, of course, stupidity. And that's where "boy racer" tuning comes into the story.

You would think that the gasoline would have a lubricating effect on the interface between needle and emulsion tube, but somehow it doesn't help enough to completely prevent wear.

So here are what I see as contributing factors to emulsion tube wear:
1. Obviously the needle, dangling from the bottom of the CV slide is going to be subjected to the "pull" force of the engine's intake vacuum and so is the the plastic CV slide (when it isn't in the fully retracted position, held up by the carb's diaphragms).
2. I've seen write-ups and pictures showing CV slides that had worn substantially against the carb body on their "downwind" side. I guess the bike with this type of wear might have been ridden in really dusty conditions, maybe? Or maybe without an airbox attached or maybe without a filter element in the airbox? But no matter how the slide wear happened it will have the effect of moving the needle further forward, causing it to rub on the emulsion tube even harder.
3. Even with the B4's OEM Suzuki-spec needle + spacer combination installed there's a little "wiggle" to the needle. I'm sure that contributes to the emulsion tube wear. But...
4. From what I've seen the aftermarket needles (Dynojet) are much more wiggly. It seems that introducing the ability to tune the needle with multi-level e-clip system makes them less stable in their seat.

It's funny that I'm talking carbs with you because I've abandoned them for fuel injection. Both of my bikes, the '93 GSF400 and my '05 EX250, have been my do-it-yourself fuel injection conversion projects. I love the older bikes but not the carbs.

Ok, this shows how much reading I've done. Now my mind is playing tricks on me where I can't remember if I READ a post where the tubes were egged, or if mine actually are. I'm having trouble with the memory. I'll check when I finish dismantling the carbs tomorrow - I had to work on another bike tonight to get it ready for a VIN inspection Monday.

I looked down the top of the carb with the top cap off and I can't see any egging so it must have been a thread I read and my mind got the two mixed up.

I'll give it another look. Hope. Don't have to replace those because they are $100 for a set of 4.

You started talking about the emulsion tubes and I realized I still have the set from my B4's carbs. So I hunted them down and put them under a USB microscope at about 100X magnification to see if they were still round.









I think they look pretty good, nice and round. If my set looks this good at 19,000 miles I'm betting your set from a B4 with only 3,800 miles on it are probably near perfect.

Thank you!! (And cool that you have a USB microscope).

I'll take mine apart tonight and shoot some pics.

Also, what's the best way to post pics up here? I've been using Tapatalk on my phone which makes it easy to post up pics but I'm not sure if they show up in the thread. Did the picture of my bike on the trailer show up in the thread or did it only give you a link?

USB microscope = about $25 on Ebay, plug and play with anything on your computer that can control a web-cam (cheap, fun, nerdy Chinese techno-trash).

Pictures = I put all of my pictures into my Photobucket account, then I re-size them to "forum friendly" size (about 700 by 500 ish). When it comes time to post I click the "Img" button and paste in a direct URL link to the picture in my Photobucket library.

Your attempt at posting a pic of your B4 was sort of a fail. It didn't show the picture itself in this forum thread and it didn't even show up as a Hyperlink. I had to copy the URL manually then open another browser window and paste it in before I could see your bike (But I did see the bike and it is a beautiful specimen).

SevenThreeSeven wrote:Your attempt at posting a pic of your B4 was sort of a fail. It didn't show the picture itself in this forum thread and it didn't even show up as a Hyperlink. I had to copy the URL manually then open another browser window and paste it in before I could see your bike (But I did see the bike and it is a beautiful specimen).

Hmm, I haven't had that issue through Tapatalk on my other forums (Dotheton, HondaTwins...etc).

No problem, I use photobucket as well. I figured the bike pic didn't work because it only showed me a link as well in my browser. Easy problem to solve, thanks.