Hanging Idle - Mixture Screws

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I didn't think my carbs had Mixture Screws. Don't ask why. I also filled my crank case with 2 gallons of oil.

Recently upgraded my coils the the Mikes XS Green ones. The bike runs great except for a hanging idle. Noticed before the upgrade that the plugs were a little white. Now the plugs have more white than before. If I understand this right. A hanging idle can happen from a lean mixture. Checked for vacuum leaks with propane. Didn't find any.

Never cleaned the mixture screw when I cleaned the carbs 1.5 years ago. Should I just drill the rubber cap out and back the screws out a half turn and see what happens? Or, should I take the carbs off. Remove the rubber diaphagm slide. Then remove and clean mixture screw? Trying to avoid a problem here. But, i work like water flows. Taking the path of least resistance.

[audijunky]

"I also filled my crank case with 2 gallons of oil."

I actually laughed out loud in my office when I read that!!! Brilliant!!!!!

[audijunky]

turn the mix screws out some. what diaphram are you talking about, the one in the top of the carb, or are you talking about the rubber plug for the mix screws?

Also , your carbs could probably use a good cleaning

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Diaphragm in top of carbs. I don't want to take those screws out if I dont need to.

Why do they need cleaning? Just did them not to long ago. Except for that darn mix screw.

[dbeardslee]

Getty - On the 80/81 carbs there's a plug that has to be removed to access the mixture screws. The mixture screws are primarily for the low-rpm idle (although it will have some affect through the rpm range, but usually not enough to make the plugs white) - after that it's your pilots, then emulsion needles and main jets. What kind of mods do you have on your ride? 4/1 exhaust? Pods? Drilled airbox? Need more details, but off the top of my head it sounds like the jetting may be off.

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No mods at all. Stock bike

[audijunky]

I am no expert, but it sounds to me like the coils are creating more spark, hotter, burning better and you need to increase the fuel a lttle bit now
Just my 2 cent,, if I were you I would go a 1/4 turn out on the mix screws. than see how it runs and recheck the plugs

[audijunky]

you may also wanna check for leaks around the carbs, seems unlikely though if all four plugs are white

[audijunky]

They would need cleaning if you didnt winterize your fuel delivery system and the bike sat for a few months without being started and run. If this is not the case then disregard.

[dbeardslee]

When is the last time your carbs were cleaned? Could be the orifices in the pilots or emulsion tubes have some varnish deposits reducing the fuel flow inside the carbs. Might try running a can of seafoam through her and see if that helps the situation. If you haven't had the mixture screws out, the 80/81's can get a fair amount of crud at the bottom where the screws seat, closing off that orifice. I doubt whether seafoam will be very effective in that location - gotta take 'em out and clean the tunnel. If you do run the seafoam through, try to keep your rpms down (3k or below) for most of the tank - then open her up. You won't get the full benefit of the seafoam if you're running at high rpms. JAT

[Crazcnuk]

The caps that cover the mix screws are aluminum.... Don't be drilling out any rubber plugs!

Removal of the slides/diaphragms isn't necessary for anything but cleaning, or adjusting the needles.

If your bike is running well, you may not need to clean the mix screws, but you should adjust them whenever you do yo a tune-up or carb clean. If they adjust properly, then you can leave them alone, if not, they need to be cleaned, and possible new o-rings.

[Winterhawk]

Turn the idle down. This is what is causing this. Sync them and set the idle mixture screws to the lean best idle setting then set the idle speed until it idles smooth with no hang up when letting off the throttle. When you rev it and it drops below the normal idle speed then stabilizes it's too rich. When you rev it and let off and it increases for a sec it's to lean.

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YES!!! Got it. Started with 3/8 of a turn. She was a little sluggish without a hanging idle. Then I started another carb sync and adjusted the mixture to a 1/4 turn ccw from starting position (1/8 less than the first 3/8). Synced again. PERRRRRRRRRRRRRFECT. Runs smooth/quick. And no hanging idle.

Just put new tires on her. And had the wheel shop take a warp out of the right front rotor. After the SS brake lines arrive she will be 100%.

Thanks for all the help.