Question about the rubber plugs on pilot jet passage.

[Squishy]

but why would it suck fuel through the connection port and pilot jet tube when it can just suck more easily from the main jet?

The short answer is: Because it can. (it's the whole "path of least resistance" thing)

Think about this hypothetical situation: If you were to keep installing a bigger and bigger Main Jet (larger orifice) what would happen?  Well, for any given level of vacuum the bigger Main Jet would flow more fuel.  This would be true up to the point where the Main Jet orifice is so large it "defeats" the given amount of vacuum.

Well no, the main jet only really makes a difference until you are WOT and the needle is fully up. 

Anyway I'll order the plugs today and after the weekend I'll see what happens.

[Gouraami]

I plugged my pilots yesterday. Was a bit of a rush job, but was surprised to discover an extremely lean 3 cylinder running bandit once reassembled. I haven't had a chance to check what is going on there, but it is currently a non runner  .

[Squishy]

Bad news.. plugs didn't change anything. It's still dipping below set idle speed occasionally.
I did drop down the needles to stock and that improved the riding-away-bog a lot..

Gonna try to change the mixture screws again this week... I can't reach them on the bike so I have to remove the carbs every time 

[Gouraami]

having any luck yet Squishy?

I have been fiddling with mine, but keep on getting the same symptoms. I havn't had time lately to post on the forum about it.

Summary of what I have been doing:

1: Adjust pilot screws (leaner) - low end running improves - start getting a lean issue at 6000rpm... I think: "is there a performance drop when under full throttle ?"
2: Adjust pilot screws again (leaner) - low end running improves more - starts becoming hesitant at 6000rpm... "definetly a performance drop at full throttle".
3: Adjust pilot screws again  (even leaner) - low end running improves even more! - starts bogging at 6000rpm... at full throttle - "is this a 400cc?"

4: "I will sort this out by bringing the needles up a notch  "
 
It would start Bogging at low rpm again once the needle was adjusted richer. I would then start from "1" again at the new needle position.

Clearly I am getting nowhere. Moving on: I am going to adjust the float heights to be 1mm higher over the weekend (less fuel in the carb bowls), will update when I have a chance.

[Squishy]

Well, yes the GSX600F runs fine.
The rubber plugs didn't change anything.

The low end hesitation was due to needles +1 rich.
I had the same symptoms on my 400 when I had set it to +2 rich, and went high in the mountains.
I didn't think the GSX600F would have the same richness problem, with only +1. It does however have stock exhaust... so maybe that's why.

The mixture setting is still at 1.75x instead of 1.5x. I think it would be better at 1.5x, it still dips a little, but overall it's runs fine now. I've mounted the fairing now and don't want to remove everything just to try it. Can't reach from under like on the 400.

About your problem. I don't think the pilot screws should be affecting anything at 6000rpm.  At full throttle, the only limiting factor should be the main jet.
The mid-range flat spot on the 400 is removed (on my bike) with open exhaust and +1 or even +2 rich on the needle.
I have the mixture screw at 2x out.

[Gouraami]

From all my buggering about I can confirm one thing, pilot screw adjustment affects the performance at all RPMs

[Squishy]

From all my buggering about I can confirm one thing, pilot screw adjustment affects the performance at all RPMs

Yes it affects the whole range, but not such much the higher more throttle position you go.

Don't forget, the fuel that goes across the mixture screw, comes from the main jet (and then through the pilot jet). If you are limited by the main jet (which you will be at WOT - opening the mixture screw won't give more fuel because it's already at the limit. At most, you will allow more air from the air jet up front. But compared to the gaping 34mm hole at the front of your carb it shouldn't affect it that much.

[Gouraami]

For anyone following this thread hoping for answers, my problem was running the incorrect jet needle and needle jet combination.

[Squishy]

For anyone following this thread hoping for answers, my problem was running the incorrect jet needle and needle jet combination.

Non-stock?

[Gouraami]

I have two sets of carbs, a 32mm and a 33mm. During stripping, cleaning and picking the best parts I ended up with stock 32mm jet needles in my 33mm carbs still running the 33mm Needle jets.

It turns out the the 32mm carb jet needle is slightly wider in diameter than the 33mm variant.

Mid range was better with the 32mm jet needles, but low end terrible.