CV Flatsides pilot jet size and fuel screw turns

[stain]

I am using the Mikuni BDST model from a 89 GSXR1100. Are these what you are using or did they put different carbs on some? I am trying to follow some of these threads concerning tuning these 36's on the GS 1000 but there are so many models its hard to get a direction. Right now I am at 147.5 mikuni mains, 37.5 pilot, 2 turns out on the fuel screw, needle up all the way and 1 slide hole plugged. It still seems to be a little lean with a little stumble in the midrange but it screams on top. Plugs still too white. Also my idle is inconsistant. I am really condidering RS 36 or 34's.

[posplayr]

I am using the Mikuni BDST model from a 89 GSXR1100. Are these what you are using or did they put different carbs on some? I am trying to follow some of these threads concerning tuning these 36's on the GS 1000 but there are so many models its hard to get a direction. Right now I am at 147.5 mikuni mains, 37.5 pilot, 2 turns out on the fuel screw, needle up all the way and 1 slide hole plugged. It still seems to be a little lean with a little stumble in the midrange but it screams on top. Plugs still too white. Also my idle is inconsistant. I am really condidering RS 36 or 34's.

The 36mm slingshot GSXR carbs are all BST36SS which is what I have listed.

BDST is a down draft and did not come on the GSXR 2nd Generation Slingshots (GSXR 1100's used BST36SS).

http://www.motorcyclecarbs.com/Mikuni_BDST_Carburetor_C686.cfm

Right now I am at 147.5 mikuni mains, 37.5 pilot, 2 turns out on the fuel screw, needle up all the way and 1 slide hole plugged.

That sounds like what would be my exact starting point(I'm just sorting out the combinations at the moment; I have three sets one bing on my GSXR 1052 1st Gen).

Hum, what jet needles and needle jets are you using?
Dynojet or Factory pro?

What size is your MAJ?

[posplayr]

If you really have BDST down draft carbs your float level is probably screwed up with the angle difference.

That would probbaly cause the inconsistency of idle and lean condition at low RPM.

[stain]

--My MAJ is 1.5. I am using factory pro needles and emulsion tubes which are mikuni parts.
I think I may be confused as to which carbs I have. I bought them as 89 GSXR1100 carbs but they look like BDST carbs. When getting parts I always use the 89 GSXR fiche and the internals look the same. I did notice after reading these posts that the float bowl sealing surface is not level when the carb is, That is the tops are flat but the float bowl sealing surface is tilted ? ? ?

[posplayr]

--My MAJ is 1.5. I am using factory pro needles and emulsion tubes which are mikuni parts.
I think I may be confused as to which carbs I have. I bought them as 89 GSXR1100 carbs but they look like BDST carbs. When getting parts I always use the 89 GSXR fiche and the internals look the same. I did notice after reading these posts that the float bowl sealing surface is not level when the carb is, That is the tops are flat but the float bowl sealing surface is tilted ? ? ?

I'm guessing BDST and BST share parts but the main carb body is different, floats need to be level. Everything else sounds right on.

So your jets are probably the O-8's if you bought them from the parts Finche for the 89 GSXR 1100

[stain]

Yes they are 0-8 but I bought them from Factory pro. The stock ones were so far worn I don't know how the previous bike even idled!!
Should I try to get some intake boots to level the carbs or do you think I can work with the float adjustments enough to get them correct? Did any GSXR come with BDST's?

[posplayr]

Yes they are 0-8 but I bought them from Factory pro. The stock ones were so far worn I don't know how the previous bike even idled!!
Should I try to get some intake boots to level the carbs or do you think I can work with the float adjustments enough to get them correct? Did any GSXR come with BDST's?

Yea Factory pro kits use the stock emulation tubes.

I mentioned already all GSXR 2nd gen 1100's (89-92) are BST

[stain]

But what did the BDST come on, if any, Suzuki's ? Does anyone have a picture of the BST mounted on a GS1000/1100?
Also how big a role does the MAJ play? Facory pro makes no mention of it in there jet kit.

[posplayr]

But what did the BDST come on, if any, Suzuki's ? Does anyone have a picture of the BST mounted on a GS1000/1100?
Also how big a role does the MAJ play? Facory pro makes no mention of it in there jet kit.

I think I would find some BST's and swap your parts into them.

I think the MAJ causes changes in the MJ (they must be kept somewhat in proportion).

I plan on drilling my GSXR 750's out to 1.5mm so the main will remain at about 147.5 Mikuni

[stain]

I think if I am going to spring more money for carbs they will be the RS type--

[Tomas03]

I primarily did the 750/1100 GSXR Sling carbs. The most pronounced pattern I see here is:

Main jets for stage 3 1100 are about 145 (Mikuni) 155 (Djet)

Main Air jet is 1.5 mm v.s. 0.5 for 1100 and 750 respectively but on the 1990-92 750 they increased both teh main jet and the MAJ to #127.5 and 0.9/1.2 mm where typically it would have been #112.5 and 0.5mm. So if the MAJ is smaller, then you would need a correspondingly smaller MJ. I see this seems to match your numbers were you probably had a MAJ=0.5 and ended up with a small 140 DJ main (130 Mikuni).

As far as needles are concerned about being different, I have compared the
DJ 3122.008 kit for 88-89 and Cal 90-92 GSXR 750 kit with the
DJ 3136.003 kit for 89-92 GSXR 1100 and they are identical except for larger mains in the 1100 (160/155 v.s 144/140) and there is no emulsion tubes in the 3122.008 kit.

Both 3122 and 3136 use the exact same needles (DNO356) and there is hardly any taper to them. .

Sorry for any misunderstanding but I did not use any DJ stuff. My mains, 140, are mikuni. Any comparisons I make are between factory stuff. The needles were so different the 750 needles wouldn;t fit in the 1100 emulsion tube. There was a 10mm difference in needle length, the 750 needles have 2 tapers (one big one small) the 1100's only one fine taper all the way. Your own chart is good and shows the differences. (the letter ID on the needle is the taper)
I left the 750 main air jets (got lucky there) and just changed to the 90 model 1100 emulsion tube and needle, and along with the 140 main that did the trick, running pods.
To answer your question about what is the easiest way to tell what carb you have - take out the emulsion tubes and they will tell you. Go from there.
Before doing this I did heaps of research of which I've forgotten most and there is no need for a stage 3 kit.
I have to reiterate that after I did this and synced the carbs, the bike went like hell and it was my daily ride that I rode everywhere without any problems.

[posplayr]

Sorry for any misunderstanding but I did not use any DJ stuff. My mains, 140, are mikuni. Any comparisons I make are between factory stuff. The needles were so different the 750 needles wouldn;t fit in the 1100 emulsion tube. There was a 10mm difference in needle length, the 750 needles have 2 tapers (one big one small) the 1100's only one fine taper all the way. Your own chart is good and shows the differences. (the letter ID on the needle is the taper)
I left the 750 main air jets (got lucky there) and just changed to the 90 model 1100 emulsion tube and needle, and along with the 140 main that did the trick, running pods.
To answer your question about what is the easiest way to tell what carb you have - take out the emulsion tubes and they will tell you. Go from there.
Before doing this I did heaps of research of which I've forgotten most and there is no need for a stage 3 kit.
I have to reiterate that after I did this and synced the carbs, the bike went like hell and it was my daily ride that I rode everywhere without any problems.

Thanks for clairifying I'm trying to sort out different reports by people.

A couple of Questions:

You started with a Australian set of GSXR 750 carbs?

Are you having needle/jet wear issues?

How many miles on your bike?

Looks like yours is a vintage racer and not much street riding where the needle rattle is worse.

[Tomas03]

Vintage Racer/Road Bike

The vintage racer has mikuni smoothbores

The BST's went on my road bike. Unfortunately I found it necessary to sell my girl after I did all that work, but before doing so, and after putting about 6000 miles on it I checked the carbs (because I took them off and still have them in the shed). They were fine.

I know where you're coming from though as all the guys in my race club who race gsxr's complain about he emulsion tubes wearing out and going out of round.

By the way have you checked out http://www.theflyingbanana.com/gsxrcarbies.htm. The owner of this site was my sounding board when I was going thru my trials and tribulations. It was his idea to check emulsion tubes as they might be worn. They weren't worn.

[Tomas03]

You started with a Australian set of GSXR 750 carbs?.

Whilst jabbering away forgot to answer Yes. But the innards are the same as the UK one on your chart.

[stain]

You kept the 0.5 MAJ and ran the the larger mains for the 1100--correct? Did you tune with the MAJ at all and what differences did it make? I am fighting some inconsistant idleing on my BST's ( yes finally determined they were BST's ) and was wondering the role of the MAJ.
It's hard to compare tuning with the Dyno-jet stuff and Mikuni parts due to the diffences in the jet needle and needle jet. I am going to stick with all mikuni parts for now