Pinned Needles and needle jets/emulsion tubes - FZR250 Mikuni BDST28 Carurettors

My memory may be incorrect, however I believe I've been through most of that site in search of potential alternative emulsion tubes - vague recollection that N-8 was a consistent problem as most tubes started at O-0 - (OH - Zero), which could be made to work with another needle of appropriate dimensions

It all gets very complex very quickly unfortunately

 

I've got 4 keyster emulsion tubes that I won't use if anyone is interested, 3LN3/5. I only have 3LN6/7 carbs left and unfortunately they're different. Brand new, never used. PM me, I'll let them go cheap.

 

An old thread I know, but as we all know, Fizzer carbs are problem that just wakes you in the middle of the night thinking I might have a solution.

On a whim I purchased a set of '93 MC22 carbs from @kiffsta (really nice guy and I was pleased to meet him and see his projects).
I purchased them to pass some time while I'm stuck in Brisbane, and to see if they can possibly be re-racked to go onto a Fizzer.

Preliminary disassembly says yes it's doable and actually quite easy for the mechanical elements and should require disassembly of the set, moving some butterfly mechanisms and drilling and tapping three holes - it's actually quite simple.

Another good thing is that @maelstrom has full o-ring and seal sets available for these carbs, which I will be fitting once the spacing mods are done.

I will do a writeup once I've got a good camera to hand for pics.

There still remains the possible issue of a suitable needle, because the fizzer needles are dual taper with the first taper shallow and the second taper to the tip steeper, whereas the MC22 needles have a steep first taper and a shallower second taper.

I'm slowly trawling through Keihin needle data to get my head around it, but hopefully there will be something suitable in their lineup.

 

OK so I've been looking at some needles in various online charts - @my67xr located the diameter of the very top of the MC22 needles, it is 2.9mm, whereas Mikuni needles are 2.6mm - that's a challenge right there, however I stopped in again at Motorecycle @kiffsta and also grabbed a set of ZXR250 carbs, just to stickybeak them also and to measure the needles

All of this is a little preemptory as the carbs haven't been tested as they are as @Murdo has advised, but if the fuelling is seriously out of whack because of the MC22 needle taper, it's nice to at least have options IF that component needs attention

 

Hmm... something interesting that might help is that I found, based on an old post by @GreyImport that chinese suzuki bandit 250 diaphragms (relatively cheap) fit and work well in 3LN's. I wonder... just wonder... what about the needles?

 

@Joker - I realise that your post is over a year old and at the risk of doing myself out of a bargain, do you still have the emulsion tubes as I lost 4 complete Keyster carb kits off of the back of the ute last week.

FWIW - the 3LN3/5 and 3LN6/7 emulsion tubes are the same according to the specs on this page
https://www.2fiftycc.com/index.php?...8-26mm-carb-settings-specs-3ln-3yx-zeal.9787/

So if you've still got the tubes and they're from 3LN3/5 I'd also need the pilot jets, plot air jets, started jets and main jets to make sure that everything matches if you still have them

 

I'll have to have a look in the shed... I literally cleaned out all my 250 stuff recently. Got sick of it all. But I may have kept those. I have tried 3LN3/5 emulsion tubes in a 3LN6/7 carburetor set but they don't fit. There are differences making them incompatible, I think it's to do with the seating of the tubes into the carburetor body (I'm a bit rusty on what the problem was I just know I was very annoyed not to be able to use them).

 

I have been intending to come down to you and get that 250 transmission, however I've not been in Victoria much at all in recent months, so I guess I'm too late for that, but if the emulsion tubes are still lurking, I'm definitely interested

I will very likely be in Melbourne on the 6th of May

 

Well, it was a while since I installed the keyster kit in the FZR, but now and then the engine stalls and cold starts are an disaster. So I bite the bullit and try to get the original parts.
Four years ago, needles and tubes were easely available, but now, only the tubes... sigh.
I tried to get some info from neighbour countries, like Germany and Austria. There are some companies that are listing the original needles. Contacted them, but no answer yet..hmm, not good either.

CMSNL does not carry the FZR250 at all.

Megazip does still carry them:
https://www.megazip.net/search?q=3LN-1490J-30-00
and
https://www.megazip.net/search?q=3LN-1490J-20-00

Is Megazip reliable? Never bought anything there.

 

Cannot register at Impex? Some kind of server error.

 

Succeeded now. Made an account and paid. Now wait and see what happens.

 

Well, unfortunately, today I received an message: status: cancelled!
"Item is impossible to order, out of production"

Anyone other good idea's?