Bleed Screws

[Rocket Guy]

I am trying to get the carbs on my '82 adjusted.  My problem right now is the bleed screws.  My question is, does screwing the bleed screw in make the mixture richer or leaner?

TIA,

Greg

[zore]

I'm not sure what you are referring to as a bleed screw.



number 3 is the Idle Mixture screw.  Everyone has their method of adjusting it but here is how I do mine.  First off, I'd screw the screw in until it seats and keep track on the number of turns you're screwing it in.  This way you can always bring it back to the way it was before you "tuned" on it. 

Get the bike warm so it idles and set the idle to 1200 rpm with the Idle adjustment knob located on the right side of the bike. 

Now back the idle mixture adjustment screw out or in until you notice the idle speed rise.  When the idle is at it's highest point, lower the idle with the adjustment knob back to 1200 rpm.  Now do the same to the second carb.  I repeat this 2 or 3 times until it's good.  Remember that the further out the screw is turned, the more fuel you'll burn at idle so I'll take it to where the highest idle point and then start turning it back in provided the idle speed doesn't change.

Keep in mind that if you have other issues with your carbs, this wont work.  Pic was taken off http://www.xz550.com/bowl.html

[silicon_toad2000]

screwing the idle mixture screw in makes it leaner, out makes it richer

[Lucky]

Actually, that's wrong, but it's ok to think of it that way if it helps. here's why:

The pilot (or idle) mixture screw meters the amount of air/fuel bypassing the throttle plates.  fuel & air are already mixed when they reach the needle, so your really only changing the AMOUNT of mixture bypassing the throttle plates.

that's your carb lesson for today.
--Lucky

[silicon_toad2000]

you knew you'd get a bite didn't you lucky.

The air jet in the idle circut is to allow air to be mixed or 'emulsified' with fuel. The same as the main circut.
Generally my understanding of the term mixture is the stuff that fills the cylinder.
So if the idle circut allowed 'mixture' to bypass the throttle plates, then the bike would still run if the throttle plates were completely closed and you could adjust the idle speed with the idle mixture screw.
I can see your point about air and fuel being emulsified when it passes the adjustment needle, and that the emulsified fuel will only be changed by the idle air jet, the idle jet and the float level (which actually impacts on the progressive circut more than the idle circut). I do think it is a long bow to draw to call the emulsified fuel used by the idle circut the mixture.
The air is mixed with the fuel to reduce the mass of the fluid so it more closely matches the flow of air, reduces the inertia to the fluid to make it more responsive to changes in the vacuum signal from the carb.

For homework I would like you all perform some kind of maintenance on you bikes and once that is complete you will have to ride you bikes until you grin involuntarily.

[Ron_McCoy]

Sorry, just looking at my bike makes me grin involuntarily.

Ron

I will, however do my homework.

[Lucky]

So if the idle circut allowed 'mixture' to bypass the throttle plates, then the bike would still run if the throttle plates were completely closed and you could adjust the idle speed with the idle mixture screw.

if the throttles were completly closed then there wouldn't be any vacuume to emulsify the fuel & air...

[silicon_toad2000]

The idle outlet is under the throttle, the engine is trying to draw in air, creating a vacuum under the throttle plates.
If the throttle plates were fully closed and the starter was turning the engine over, theres plenty of vacuum to draw fuel and air through the carb.

[Coil Coyle]

But no air, so it would be rich.

Lucky, you forgot the pure air passing the plate in your first post.

Back to my homework ;) grinning ;D

coil

[jasonm.]

Low speed screws...CW in leaner.  No matter what Lucky says. An EGA(exhaust gas analyzer) machine does not lie. On one of these. 3 to 4 turns out CCW from tight, is in the ballpark.

[Rocket Guy]

Thanks for all of the inputs.  I thought CW was leaner.

I think I have other issues like needing to change jets on the front carb because it is set at less than 1 turn out from seated.

[Lucky]

Geeze.. beat me up!
my post is technicly correct, you guys are splitting hairs now

[silicon_toad2000]

appology accepted, no more confusing the issue.   ;D