Idle trouble+hanging rpms

[dbens]

Ive been doin searches for a couple days and tried some things out but nothing has fixed my problem.

First off, its a 1996 Kat600 with 2600 miles all stock to my knowledge.
Problems: it's got rough idle, when starting up at half choke, if you open the throttle a little too quick it just kills the bike. you gotta open it slow, and even then the rpms are rough and slow.
If you do try to open it slow then rev high, the rpms rev right to about 2900-3000 STOP for a second then quickly and smoothly rise to 6-7 whatever rpm.

Now ^ was at startup, after riding for awhile, coming to stops, the rpms will drop to about 3k where it hangs then slowly drops to maybe 1.5k. but after maybe 6 seconds at 1.5k it'll then drop to about 900. Sometimes itll stall here but most of the time it fluctuates from 900-1100 but very consistently. sort of like clockwork, reving between 900 and 1100..kinds sounds like the bike is breathing.

So i read through carbs101, took out the carbs, tried to clean them as best as i could following carbs 101. I got the the pilot jets cleaned and the main jets. I checked to make sure the throttle cables werent getting pinched or too tight or anything. I tried to test for vacuum leaks spraying wd40. I checked the air filter, seems clean.

Im still having trouble though and im not sure what i need to do next.
**I accidently did skip the step about taking out the diaphram slides w/the emulsion tubes..i know i should go back and take care of it, but dont know if thats my problem.
**The baffles on this bike have been punched through, not sure if that's a big deal or not but ive heard stuff about exhausts needing the right backpressure and stuff
**I havnt pulled the plugs, i dont really want to spend $40 on those NGK CR9EK plugs, are there cheaper alternatives?

any help would great- Thanks

oh yeah, and A/F screws have been turned 1.75 out

[kevin2502000]

I believe everyone is pretty much in agreement that a/f should be 2.25-2.50 out for stock set up. I would pull those plugs and see what they look like. How does this only have 2600 miles on it? Or did you mean 26k?

[Kreylyn]

I would change the A/F default starting setting to 2.5. The stock setting is a little lean to start with, and that is one possible reason for the idle.

The second thing I would do is go ahead and go back to that step you skipped, inspect the diaphrams, make sure the emulsion tubes are clean, and not worn.

Krey

[dbens]

Alright, i just went back and pulled the emulsion tubes. cleaned them, although they already looked pretty clean, the holes are clear though.

Ill set the AF screws back out some more and see how that goes

[Cheriff]

I saw you already checked for vacuum leak, but is the line off of carb 4 which opens the petcock connected? I left that off once and it sounded similar to your description. But definitely turn those screws out a little more first. Even though it seems like a small amount, 1/4 or 1/2 turn can make a big difference.

--

Wrote that before I saw your last response.

[DumbLuck]

if you think the carbs are clean, clean um again. the passages plug easy, and so do the jets. your definition of clean may be way different than the skoot's. one carb at a time, on the rail. lots and lots of carb cleaner and lots and lots of compressed air. pay close attention to the pilot circuit. that's what feeds the skoot up untill 3 - 4k when the slides start opening, raising the needle jets. dont forget the pilot air jet up there on top under the slide diaphram.

[dbens]

Alright, well i just got back from a good ride, and you all were definitely right on the A/F screw. after i got the carbs back in, screws out 2.25 turns the thing idles perfectly. crazy how much of a difference it makes.

Thanks everyone for the advice and help!
-Dan