Hello fellow Gixxer people!
As my title say, I have changed my old used up ( ) Gsxr400(89mod) carburetors with some bandit gsf400 carburetors (91mod).

They fitted as expected, and after finding someone on the internet saying I needed to change the Main jet and the needle from my original carburetors, I did before mounting. That seemed fair, and I changed the 100 something main jet from bandit with my 97,x mainjet from the original gixxer carburetors. (Bandit from the EU, not US)
Started the bike and the Idle don't go under 3k ; rises with choke. No power when mid/full throttle,and needle height did not help.
I figured that it's pretty obvious that it's running lean, but do I put back the 100 nozzle and try?
The Pilot screw is 1,5-2 turns on original carburetors, but think the bandit had 3,x turns. Anything to mess with?

I'm tired of using time on the carburetors now, and the girls in my life is starting to get worried about my obsession of this old ugly bike (they're words), so I hope I can get some pinpoints from the blessed people of Greybikes, so I dont loose my mind and my girlfriend or most importantly my beloved bike.

So if anyone have done this before and have an recipe on what main jet and/or needle adjustments that I need to do, or have any input at all, I would appreciate it a whole bunch !

Unless I'm missing something here You can't use bandit 400 carbs or gk73a carbs on a 76a.
The 76a is semi downdraft, the bandit carbs are conventional. You will have to fight on with the 76a carbs.

Here they are : http://www.ebay.com/itm/Used-Suzuki-GSF ... SI:US:1123
I did not see any difference in anyway, except for the slightly longer needle, and an bigger main-jet.

Post a picture of your bike. Is it a 73 or a 76a? You say you have a 89 gk76A?! They don't exist.. gk76a made from 1990.

http://www.suzukicycles.org/GSX-R-series/GSX-R400.shtml

- High revs on idle, can be throttles miles out of synchro or chronic air leaks at manifold or through carb o rings.

moforockband wrote:Post a picture of your bike. Is it a 73 or a 76a? You say you have a 89 gk76A?! They don't exist.. gk76a made from 1990.

http://www.suzukicycles.org/GSX-R-series/GSX-R400.shtml

- High revs on idle, can be throttles miles out of synchro or chronic air leaks at manifold or through carb o rings.

Yes yes, Im sorry, It's an GK73A, my bad
EDIT: Bonus pic http://imgur.com/L2YjwRd

These carbs are all ancient now, and need the internal o-rings replacing if they have not been done, to get them to run properly, and keep your engine from flooding etc.
The bandit came with 32mm and 33mm cv carbs, check you are replacing like with like, as they use different carb rubbers. Measure the internal bore to check you have bought the correct ones,
The carbs are easy to clean out with comp air and solvent, no need for ultrasonic cleaning. There's some youtube vids to show the refurbishment process for the gk73a.

Few tips-
Spray carb cleaner around the rubbers to identify leaks
Check throttles are synced with vacuum balance gauges.
If your valve clearances are massively out, or your engine has very low compression it will not idle nice!
- settings 2 turns out on mixture. make sure idle jets are clean and correct size. Set needle to std (usually clip 2 position). You can forget about the main jet, this has no effect on idle.

There's lots to go wrong, it all needs working through methodically!

moforockband wrote:These carbs are all ancient now, and need the internal o-rings replacing if they have not been done, to get them to run properly, and keep your engine from flooding etc.
The bandit came with 32mm and 33mm cv carbs, check you are replacing like with like, as they use different carb rubbers. Measure the internal bore to check you have bought the correct ones,
The carbs are easy to clean out with comp air and solvent, no need for ultrasonic cleaning. There's some youtube vids to show the refurbishment process for the gk73a.

Few tips-
Spray carb cleaner around the rubbers to identify leaks
Check throttles are synced with vacuum balance gauges.
If your valve clearances are massively out, or your engine has very low compression it will not idle nice!
- settings 2 turns out on mixture. make sure idle jets are clean and correct size. Set needle to std (usually clip 2 position). You can forget about the main jet, this has no effect on idle.

There's lots to go wrong, it all needs working through methodically!

Thanks for lots of good information! =) Yes, should have changed the seals when I had it up, will do that next, was just thinking(hoping) they would be ok since it was 91, nvm. Have checked for leaks around the rubber and it looked good.
Will also measure the size of the carburetors.
Do you know if it's likely that I need to go up in main jet (nozzle) size if the carburetor is smaller? And /or can leave it alone if it's same size;just change the seals and hope.. :) Thanks again

All the gsxr400's from your era use quite restricted airboxes and small main jets to keep the power delivery constant, so if you are still using the std airbox, filter and intake snorkel then just jet it to Suzuki specs, which for your bike is 97.5. Your bike uses the 32mm carbs.

If you remove the airbox, or drill holes etc you have to increase the main jet, and risk it running lean/or poorly.

Have you changed all jets over?

I cannot remember if the pilot jets are the same, also the pilot air jet but they may be different .
And check that the throttle is fully closing, not the slides as these are opened by vacuum but the actual plates that are opened by the throttle cable.

I had a quick look.
32mm carbs use a 35 pilot jet - there is no data for pilot/main air jets (perhaps they are pressed in and un-replaceable?)_

33mm carbs use a 32.5 (leaner)pilot jet with a 1.2mm Pilot air jet. The main air jet is 0.6mm as std.

Due to the difficulty in removing the small jets in these carbs, I recommend enriching the mixture 1st. You have to use a perfect fitting flat blade screw driver to remove the jets or..... Get the drill out!