MYSTERY part(s)

[Gorminrider]

I wonder if it slows air at some port under it or, by "turbulating" around the edge of the throat also makes the throat "apparently" a smaller diameter... These are BS30SS carbs

[barnbiketom]

I really almost didn't find it on the fiche.. but read down the list of parts and saw NET haha.
I don't know what they do.. or DID.. but they don't do it anymore hahaha and unless someone tells me it will gain me some low end torque, they are staying OUT!!!! I was already looking on ebay for an airbox because the PO had nearly ruined it... and I was actually contemplating ..ahem..pods..
If I had to remove he carbs again I duno what might happen!!

[JEEPRUSTY]

Yeah they would disrupt laminar flow in the runners would they not.

[barnbiketom]

http://www.ebay.com/itm/SUZUKI-80-81-GS-250T-GS250T-CARBURETORS-CARBS-CARBURATERS-CARBURETERS-/230832560821?pt=Motorcycles_Parts_Accessories&hash =item35beb15ab5&vxp=mtr
ebay listing for carbs with mystery parts visible in TWO pics....

[barnbiketom]

Yeah they would disrupt laminar flow in the runners would they not.

They must have wanted turbulent flow?? but why?
or instead of optimizin the intake runner length, they used these to 'cheat' it out, somehow??
Actually, my brother in law just bought a GS 250 also.. it is running and I'll compare the two bikes.. altho who knows the condition of his ???

[Gorminrider]

my brother in law just bought a GS 250 also

THAT will be interesting he has the mesh.. I don't actually recall any little ports that'd be under the mesh come to think, so I'm swaying towards turbulator slowing airflow/reducing carb throat.... I would not be suprised if you had the same head as my GSX400 but I would have to look it up to see if that is true per valve sizes etc... if the smaller pistons are sucking through the same ports...? If you notice some trouble in the bike's "Pickup"? these thingies might just be important.

I have 34SS carbs though versus your 30SS. Something to mine on the web.hmm

[Grimly]

They're atomiser meshes.
Some carb designs benefit from them, when combined with a particular intake manifold or tract length - others don't benefit at all, and might even be hindered by them.
When parts-bin specials are put together by Suzuki, they might have found the carbs weren't quite right and low airflow over the jet wasn't atomising the fuel properly, so these were fitted as a factory bodge. As I say, some work, some don't.
I know for a fact the downdraught Webers benefit from them, as a significant amount of fuel can drop out of suspension in the intake manifold, leading to rougher running and bad economy.
As you will see from your examples, they get eroded away and the risk is that pieces of them can break off and find their way into the bores.

This is a really old trick, going back pre-war, and only shows there's nothing new about most of the things we think are so. It's all been done before, but the metallurgy of the first efforts wasn't good enough, and many good ideas got shelved until materials improved.

[barnbiketom]

They're atomiser meshes.
Some carb designs benefit from them, when combined with a particular intake manifold or tract length - others don't benefit at all, and might even be hindered by them.
When parts-bin specials are put together by Suzuki, they might have found the carbs weren't quite right and low airflow over the jet wasn't atomising the fuel properly, so these were fitted as a factory bodge. As I say, some work, some don't.
I know for a fact the downdraught Webers benefit from them, as a significant amount of fuel can drop out of suspension in the intake manifold, leading to rougher running and bad economy.
As you will see from your examples, they get eroded away and the risk is that pieces of them can break off and find their way into the bores.

This is a really old trick, going back pre-war, and only shows there's nothing new about most of the things we think are so. It's all been done before, but the metallurgy of the first efforts wasn't good enough, and many good ideas got shelved until materials improved.

Thanks Dave!! the bike really doesn't have much low end grunt, as expected, but I wonder if these things might just help? I won't be placing them back in anytime soon, unless my brother-in-law's same model bike trounces it!

[Gorminrider]

Yes, thanks for the excellent explain, Grimly!

barnbiketom, Don't neglect to report back. I'm a little disappointed you feel the 250 with it's "GSX" head is a bit weak. I can appreciate it's no Thumper and never could be but it shouldn't be too bad overall for a 250....If Suzuki was "tinkering" to get the carbs up to speed....well, anyways-replacing the screens with a stainless steel variety would be a thought....

[barnbiketom]

Yes, thanks for the excellent explain, Grimly!

barnbiketom, Don't neglect to report back. I'm a little disappointed you feel the 250 with it's "GSX" head is a bit weak. I can appreciate it's no Thumper and never could be but it shouldn't be too bad overall for a 250....If Suzuki was "tinkering" to get the carbs up to speed....well, anyways-replacing the screens with a stainless steel variety would be a thought....

If my bro in law's performs better grunt wise then I'll jerk it back apart...ooh well hahaah

It's not that it is weak in that sense... actually it will really scream, but you need to twist it up.. keep the revs up. not nearly as peaky as , say an RD 250/350, and it is fairly "tractable" but I'm 190 lbs..and going up my driveway, unless I get it going, it won't take the gas well at all.
My last outing on it I felt that everything was fine and ran it up to 85 mph and it was still going, so this bike does go.. altho at 60 mph the revs are , i think 7000!!
My brother in law got one also, and I rode it on his road, on the level and cant really say how it ran, it was the maiden voyage after rescuing that one too.. I really didn't thash it at all because we were sorting it out. It ran fine after sitting who knows how long???? carbs seemed fine etc..
I'm going over in the next few days to help put on new tires on his and I will surely report my findings!!!!:

[Gorminrider]

Aah so! 85mph? Yikes! I would be too scared to take my 400 up to that with me as mechanic!
But can't be much wrong with her for sure......you know, you can hope that that might be what they are for ie:

unless I get it going, it won't take the gas well at all

...I've been looking around per "atomiser rings". I even found some decent pictures in the Haynes 250-450 manual ! (available BikeCliff's Website)....
here's some links that lead me to that hope...the first is interesting because it mentions specific for "CV carbs", and CV carbs were really Popular to meet the air-pollution regs, so perhaps they were too lean and this is the "factory Bodge" as Grimly says to give them some low speed takeoff power.

http://www.vtwinmfg.com/webapp/wcs/stores/servlet/VTwinProd1_10101_10102_3309218_-1

http://www.wwag.com/cgi-bin/WebObjects/WebSite.woa/wa/DirectAction?action=forceEnglish&page=!52015

[barnbiketom]

In service on 1000īs of Harley-Davidsons for better fuel mileage, improved throttle response and improved overall performance. Carburetor “stand-off” and low speed cough is virtually eliminated. Atomizers convert your manifold into a maelstrom mixing chamber with improved fuel/gas atomization and intake manifold efficiency. Donīt wait, turbulate!

WOW a HD that doesn't COUGH hhaha.hhhmm.."low speed" and "stand off" to me means low end..
I haven't tried the other gs250, the wheels are off of it for tires and we haven't made much progress, and I'm going to Gettysburg PA to visit my SON and go ghost hunting tomorrow hahahah.. I'll take pics but I really really need to try the other bike to compare.. not to say the mystery parts are in that one either???

[Grimly]

http://www.wwag.com/cgi-bin/WebObjec...sh&page=!52015

Damn! Now this got my wallet twitching.

http://www.wwag.com/cgi-bin/WebObjects/WebSite.woa/wa/DirectAction?page=!WW8716

[Gorminrider]

Well! "Donīt wait-Turbulate!", Grimly! (too funny)

[Grimly]

The odd thing is; I independently thought of the atomiser mesh about 40 years ago, and you can imagine my disappointment when I discovered it had been thought of long, long before. Bang went my dreams of riches for selling bolt-on horsepower. Anyway, as I said earlier, I discovered they were effective on some carbs, but in spite of my long experience with SUs, I've never felt the need to try a mesh on one, as I've found the proper selection of needle was sufficient to atomise fuel properly.
However, I've gone as far as I want to with the current installation and now it's just fiddling at the edges - and one of these might be just the thing to eliminate a slight "Harley-like cough" that occurs in the transition period between start-up and 10 miles warmed up.
It's an easy enough thing to make, but the sealing of it into the carb/manifold is slightly problematic and an off-the-shelf solution like this avoids much trouble, and for the time saved is probably worth the money.