What are your low speed fuels screws set at?

Generally, at idle, just want to turn in your fuel screw until idle starts to drop off, then back it out until its at its highest rpm then turn it in 1/2 turn. then do the next carb and so on.
Jet kits often come with bigger pilot jets(small idle jets) and it can require less turns out.
Also did you adjust float levels?

 

By low speed screw, are you referring to the flat-head mixture screw above the float bowls? Currently they're all at 2.5 turns out.

Didn't adjust float levels to be honest. Would that play a role in the idle issue?

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By low speed screw, are you referring to the flat-head mixture screw above the float bowls? Currently they're all at 2.5 turns out.

Didn't adjust float levels to be honest. Would that play a role in the idle issue?

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I've done a little more research and found on another thread that if the engine is lean at idle, the rpms will hang at 2k after the rpms drop from a blipped throttle. The low speed / mixture screw is to be turned out 1/2 a turn if there is a lean condition. However, the dynojet (and what I have done now) says to turn tighten them snug, then turn them out 2.5 turns. Should I continue to turn out the screw 1/2 turn?

Taken from another post a while back, it was noted the below.

NOTE: A lean problem gets better as the engine heats up.
o If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!

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I'm about to take the damn thing to a shop since at this point, I've had the carbs on and off longer than I've been riding this season.

Any thoughts? Oh, and it's a 97 gsxr 600

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You're gunna take it to a shop, pay $200.00 get a shoulder shrug and nothing fixed. OR ur gunna pay $500.00 and it MIGHT get fixed.

But I'm prejudice against "your local mechanic"

 

Yes, the 2.5 turns out is just a baseline. If you start getting more that 3.5 turns out though, generally speaking you would likely be over compensating for another issue causing the lean condition.

How did you clean the carbs?

It may also be a possibility that you didn't go up high enough with the pilot jets, or the needle adjustment. If up to 1 full turn out on the fuel/air screws don't do the trick I would look at the needle adjustment (assuming they have the adjustable circlip on the needle head) If that doesn't do it, I would look into going up one size with the pilot jets.

 

Makes sense. I'll make adjustments to each carb with 1/2 out. Should I do them all at once? Or do one by one and see if it affects idle?

Cleaned the carbs by the following:
-removed bowls, cleaned entire bowl
-replaced / clean pilot and main jets with stage one kit
-removed diaphragm and inspected for any cracks / leaks
-cleaned choke slide and ensured no dirt / rust is in any of the carb
-replaced fuel lines

All using basic carb cleaner and air compressor

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its possible that you have gunk in your pilot circuits. The PROPER way to clean them is to seperate them and soak them in chemdip or an ultrasonic bath. Im not a huge stickler for all of that and have gotten by for the most part with only having to do that on a couple sets or carbs. What I do like to do is while they are disassembled,flip them upside down and spray carb cleaner down the tube of the pilot jet on all 4 and let that sit in there for a while. I feel like it helps break up the gunk stuck to the sides of the circuits inside the carb body. It is entirely possible you are still lean because of this.

Make all the fuel air mixture screws the same amount of turns out, and do them all at the same time. Using the vacuum gauge to balance the carbs will make up for the minor differences between them.

There is a procedure on how to "tune" those Fuel/Air mixture screws individually for the real OCD folks out there. I've never needed to do it. Th F/A mixture screw is like a "Fine Adjustment" to what the jets and needles already do, so making changes on a known good and functional set of carbs is only icing on the cake. You should be able to get a smooth, proper idle with them all even. Once you get the idle figured out, balance the carbs a final time with the vacuum gauge and you should be good.

For more information, google the Idle Drop Procedure for CV Carbs.

http://xlforum.net/vbportal/forums/showthread.php?t=31262

^ This is the first link I found, the process is the same for all CV carbs though.

Also, on my old Katana, black gunk would build up on the wals around the actual butterflies, and in a particular case , actually dampen their closing action which gave it a slow to return idle. If you have them off, it worth getting in there with a tooth brush and some carb cleaner and making sure the butterflies arent sticking.

 

Last time I had the carbs off, I removed the pilot jets and sprayed the cleaner in there. Left if for about 5 minutes or so. Also when I was bench testing I ensured that the butterfly valves / throttle plates were not sticking. They returned to the close position without issue.

That link is a good read. I think what I'm going to try and do is adjust the mixture screws half a turn out. They're at 2.5 right now, so once the bike is at operating temp, I'll shut the bike off, make the adjustment, and see how it goes from there. This should be done at 1200 rpms, correct?

Next time I have them off, I will disassemble all of them for a proper soak.

If all they need is a half turn each to get the idle to stop hanging, I'm gonna be amazed.

Thanks for the help

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No problem man. Hope you get it figured out.

 

WHAT A DIFFERENCE! Turned all 4 mixture screws one more complete turn out, and it's idling / revving without any hanging rpms. Greatly appreciate all your help along the way

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