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BST36SS carb expert needed.

  • Thread starter Thread starter yoshisakan
  • Start date Start date
You both linked me to CV carb resources, these are flatslides.
 
yoshisakan said:
You both linked me to CV carb resources, these are flatslides.
Click to expand...

I have 4 sets of those BST36SS carbs, what kind are they again? They are not RS Flatslides, but even that doesn't matter; you seem to have a hacked mess and needs someone to straighten it out.
 
If those are off a 750 katana they have very small pilot jets plug up very easy. Second the oil motors dont like a weak battery when dead cold. The faster it cranks the better.
 
akckhim said:
If those are off a 750 katana they have very small pilot jets plug up very easy. Second the oil motors dont like a weak battery when dead cold. The faster it cranks the better.
Click to expand...

This is what I was thinking too. I'm going to look through the pilot circuit and replace the gas.
 
posplayr said:
I have 4 sets of those BST36SS carbs, what kind are they again? They are not RS Flatslides, but even that doesn't matter; you seem to have a hacked mess and needs someone to straighten it out.
Click to expand...

They're from a 1995 katana 750 I guess. They are mikunis, but I thought CVs were limited to the 1980s carbs.
 
yoshisakan said:
They're from a 1995 katana 750 I guess. They are mikunis, but I thought CVs were limited to the 1980s carbs.
Click to expand...

You can call the BST's a CV flatslide but that is close as they get to being a RS flat slide. The BST36/38/40SS was used on most all GSXR 750 and 1100's from 86-92 as well.
 
Oil cooled carbs
I know these carbs and you really have to go through them.
PM me your contact info and I'll walk you through it.
Bill
 
Thanks Chef, PM sent.

In short they are katana carbs, stock katana emulsion tubes, dynojet bandit 1200 needles and 155mains, mikuni 32.5 pilot jets, .5mm fuel air jet (Not removable) and 1.5mm pilot air jet (stock katana).

I'm wondering if the needle/emulsion tubes mismatch is causing a problem.
 
After talking with Chef, he helped me determine that the needles for the bandit are not compatible with emulsion tubes from the katana. Here are the breakdown of BST36SS Emulsion tube sizes from factory pro's website:

I believe these measurements are related to the needle. Which explains why the Bandit needle is smaller than the katana needle. The site also says that all emulsion tubes are 40mm in length, so any of them should be compatible. I'm going to call today to confirm.
89-97 Katana - 3.0mm
88-92 GSXR750 - 3.0mm
96-00 Bandit1200 - 2.5mm
89-98 GSXR1100 - 2.5mm

Which ever set I go with, I'm opting for nickel plated emu tubes and titanium needles. Thanks for the recommendation here Chef. I'm hoping the bandit 1200 factorypro emu tubes are compatible with dynojet bandit 1200 needles. If so I'll just get the emu tubes and call it a day.
 
After looking at the microfiche, http://www.suzukipart.com/oemparts/a/suz/50d4074df8700230d8b4f637/carburetor, I noticed that parts 6 and 9 are different between bst36's with the 3.0mm needle and those with 2.5mm needles. Will this cause a performance problem? I don't want to have to replace the piston valves if it's not necessary as they are expensive as hell. I'm thinking that it might make it draw through a little more air, but I could be completely wrong here.
 
Alright, carbs are back together. The bike idles now, almost. When I hit the throttle it will rev but then promptly dies after that rev. Previously it would die as soon as I opened the throttle, I moved the clip from 2 to 4 notches down to see this improvement. I am using 155 mains, drilled out the main air jet to 1.5mm to match the bandit setup. There is definitely something wonky with my starting/pilot circuit. Currently I'm at 1.5 air jets, 32.5 pilot jets, and the pilot jet's are covered with rubber plugs. I don't see any change in engine speed when adjusting the pilot air screws. My next plan is to bump up the pilot jets to 40s. I feel like 4 clips down and 155s should be way too rich.

Cylinder 4 is not firing and I can't figure out why its not getting fuel. It really doesn't make sense. I've checked the circuits passages and jets and it should be getting fuel. It's absolutely getting spark.
 
Last edited:
Now cylinder 1 won't fire and cylinder 4 works fine. I wonder if there's a problem with this dyna 2000 Or the coil
 
Carter - There was a tee and I figured out that each bank of carbs were steaing fuel from each other. Now i'm temporarily running a direct fuel hose to each from a 2 valve pingel. Float height is about 17mm. I increased it from 14.6, there was no discernible difference at either setting. I think I need to get a set of 40 pilot jets.

I just don't understand why it's not firing on all cylinders, when I first started it after taking the carbs apart this last time, it fired on all 4 for like 3 or 4 seconds, then cylinder 1 cut out. This is with the choke on and I know the choke circuit is working properly. I pulled the wire from cylinder 1 while it was running last and it was sparking.
 
I wonder what would happen w/o the plugs on the pilot jets. My 1990 36mm bst don't have caps on the pilots, but they're off an 1100. Maybe the 750 pilot jet plugs aren't compatible with the Bandit 12 engine, and the displacement is demanding more air/fuel than a 750 Katana would. Is it too cost prohibitive to just get needles that are designed for the 750 emulsion tubes, instead of mixing parts?

Doesn't look like the 97-2000 Bandit carbs have plugs either. Maybe the pilots are starving for fuel after initial startup
and can't replenish quick enough, that might be why it stalls after few seconds.
 
Carter - In theory that sounds like it makes sense. I started the bike with and without the plugs and there wasn't much of a difference, but I've made so many changes that I'm not sure if I fixed something else. I do know that since I drilled out the air jets to 1.5 that i'm going to need to increase the pilot jets. I'll probably try 42.5s.

Also I bought bandit emulsion tubes, so my needles/tubes match @ 2.5mm. Katanas are 3.0mm. This further complicates the tune in my mind because with the pilot jets plugged the pilot circuit gets the fuel mix from the needle jet.

I really should have got rs36's or bandit carbs, but everything I read said that bst36ss were pretty much the same across the board. I've found enough minute differences to cause a few weekends of headache and a few hundred dollars worth of parts.
 
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