idle issues.... please help!!

[worrp8nt]

I have a 1990 katana 750. I have recently encountered a fast idle issue and I cannot seem to figure it out. When I start the bike, after it is fully warmed up, the idle speed is anywhere between 2300 and 3000 rpm. After it sits idling for a few minutes, it seems to emit smoke from underneath the bike. I was unable to distinguish exactly where the smoke is coming from, but it seemed as though it was coming from or near the headers. It may just be burning oil or grease (it appears there is a layer of grease on the underside of the bike, but none on the exhaust), but I have a feeling whatever is smoking could be my problem.

Anyway, I cleaned the carbs and replaced a damaged diaphragm with no luck. I dont think I have an intake leak because I was unable to get the engine to rev up when spraying carb cleaner around the intake, but it is still plausible.

I have a vance and hines exhuast with jetted carbs and a K&N stage 3 filter kit on the bike if it is any help.

If anyone has any ideas at all as to what the problem is, I would appreciate some feedback. Thanks

[arsenic]

you just sated you're problem.
a K&N stage 3 filter kit

[worrp8nt]

See, the filters were on there when i bought the bike, and i have been told countless times that having them on there can negatively affect performance, but is it really possible for the idle to run at almost 3000 rpms just becuase of the filter kit?

[arsenic]

yup

[worrp8nt]

I will order a stock airbox asap then. question though...

wouldn't the K&N filter kits allow more airflow, there by making the mixture lean?

If my idle is high than I would have too rich of a mixture right?

Im a little confused

[BarMatt80]

before you run off and buy an $80 to $170 box or so...try some free things.

turn your a/f screws 2.25 to 2.5 turns out, needles on a 3.5 or 4, main jets 124 or 126. stock float hieght.

140 or 144 mains are way to much, go put those in a gas gussling chevy trefiddy. take them out of the bike.

this goes without saying. ensure good orings, and emulsion tubes. those are generally worn expecially a bike of your age.

it is a problem of vacuum with the pods. harder to regulate like that of the stock box.

[worrp8nt]

ok thanks ill give that a shot. Ill let you know how it works after i get that stuff done...

[arsenic]

If you do want the air box. I have one.

[worrp8nt]

i actually got one on ebay for 20 bills shipped so im all set on that... thanks though...

Im gonna see how she works after I replace the pods with an airbox and check the floats and jets

[worrp8nt]

ok so i tried everything and put the new airbox on and still a high idle...

[couplekats]

I have the same problem with a 90 600, minus the K&N filters, stock everything. swapped carbs with another bike, no change

[worrp8nt]

i got stock filters on it too now actually, this problem seems impossible!!

[arsenic]

it's not impossible, adjust you throttle cable.