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Discussion Starter #1
I am currently working on a custom project based on a 1995 GSXR1100, E34 Italian market, carbs: Mikuni BST40SS.

The bike has 4-1 headers and a SC Project slip-on, original airbox has been eliminated in favor of K&N filters.

Because of the modifications to the bike its not an option to put the original airbox back on the bike, it would also ruin the look.
Since this will be a cafe racer/scrambler type of bike I do not need top end, I want good running 1/4 thru 3/4 throttle

The bike idles great, standing still there is no problem revving up to redline, but under load it starts to struggle at 4k and basically cant climb over 5.5k.

The current status is the following:
  • carbs have been cleaned and are spotless.
  • the jet needle is in the highest position.
  • increased main jets, original: 125 - 125 - 127.5 - 125 now: 157.5 - 157.5 - 160 - 157.5
moving the jet needle and increasing the size of the main jets didn't really give a noticeable improvement.

It is clear that it isn't getting enough fuel, at this point what are my options? Since moving the jet needle to the highest position didn't help, do i need to increase the diameter of the needle jet?

There can I buy the needle jet/jet needle and which specs do you recommend for my needs?

569936


569937
 

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there was nothing as sexy as an oil burner gixxer with a set of flatsiders and pod filters. She looks well, have you considered a Pingle fuel tap that might sort out a bit more flow on the fuel. I put one on a WR1100, they are not plug and play , you need to file a bit but they work very well and they are gravity driven you just block off the vacuum on the no 3 carb

like my water cooled one , the dyno stage kits only were avaible to stage 2 for them forgotten models lol, you could have done it with them dual pods but another company called factory pro came out with a stage 3 set of jets. WCS a bit of an odd back fire now and then
 

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Discussion Starter #4
Any recommendations of websites where I can buy the needles (needle jet)? Can't find them where I usually buy carb related parts.

According to the manual the original jet needle is "6ZD13", which specifications should I look for?

So in your opinion it's enough to change the jet needle, not the needle jet?

Never heard of that fuel tap, might look into it, now it has a brand new original one.
 

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Discussion Starter #6 (Edited)
Yes, the next step is new needles with different diameter/tapers. I would get a couple in the range up and down from where you are now and start experimenting.
it seems CRB-S72-3.0 is the kit I need, as I have the the non-USA 40mm carbs with K&N 3092 filters.
Does anyone have pictures of the kit, or a list of whats included. Does it contain emulsion tubes or do I keep the stock ones?

Since I already changed the main jets do I only need the needles from the kit? If so can I get just the needles from somewhere?
gsxr1100, suzuki, tuning, carb, roadrace, products
 

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factory pro has a jet kit, congig 30 i beleive, about 150 dollars, I bout one in 96 for my bike with 40's and a yosh/vance and hines powerpak

the guy suggested a jet size and needle position with my 40's and a pod filter set and was literally right on the money, no further tuning needed, literally perfect
 

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I have an 89 1100 with a full hindle exhaust and the 40mm BST carbs. I am dumping the stock air box too. I ordered a complete stage three jet kit from Six Sigma. You tell them what bike, what mods, and what altitude and they work out the best kit for your bike. Was about 80 dollars US and includes everything you need...no gaskets though. Will let you know how they work when I have them installed.
 

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Installed the sigma kit yet? Ordered one myself a few days ago, need the bike running yesterday !
 

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factory pro has a jet kit, congig 30 i beleive, about 150 dollars, I bout one in 96 for my bike with 40's and a yosh/vance and hines powerpak

the guy suggested a jet size and needle position with my 40's and a pod filter set and was literally right on the money, no further tuning needed, literally perfect
Nice, which setup with jets and needle position did you get recommended?
 
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