Mixture screw on Vx 800 carbs

That is the mixture screw. Turn clockwise to get a leaner mixture, counter-clockwise for richer. For initial setting, try with the mixture screw open 1/4 turn. Start the engine and adjust the mixture screw for good running. After it is warmed up, lean the mixture until the engine starts to miss and then turn the screw about 1/8 turn CCW

Let's focus on adjusting the air/fuel mixture. This adjustment can help balance the fuel-to-air ratio for both cylinders. Here are the steps you can follow:

Idle Screw (Air/Fuel Mix):
The idle screw, also known as the pilot screw, adjusts the air/fuel mixture at idle. It affects the fuel flow from the pilot jets (idle jets) into the carburetors.
Locate the idle screw on your carburetor. It's usually a small black knob near the choke.
Turn the idle screw to achieve the desired idle speed. Listen to how the bike sounds while adjusting it.
Note: Adjusting the idle screw shouldn't significantly affect the mixture setting.

Pilot Screw (Idle Mixture):
The pilot screw (idle mixture screw) fine-tunes the air/fuel mixture from idle rpm up to about 1/8th throttle.
To access the pilot screws, you may need to remove the air box and carb side cover.
The factory default setting for the pilot screws is typically 2.5 turns out.
Carefully screw each one in until it lightly seats closed, and then count the number of turns.
You can adjust the pilot screws to make the mixture richer (more turns out) or leaner (less than 2.5 turns).

Dual Carburetor Sync:
Since your bike has dual carburetors, it's essential to ensure they are synchronized.
Use a vacuum gauge set to synchronize the carbs. Adjust the linkage screw until both throttle butterflies are in the same position for idle2.
Synchronization helps maintain consistent performance between the front and rear cylinders.

Check Rear Cylinder Idle:
If the rear cylinder isn't running correctly at idle, it could be due to a partially plugged idle jet.

Consider cleaning the carburetors if needed. While it can be a bit of work, it's essential for proper performance.
If the issue persists, consult a mechanic or consider opening up the carburetor for a thorough inspection.

Remember to take your time and make gradual adjustments. If you're unsure, consult your bike's service manual or seek professional assistance.

Adjusting the Mixture Screws - VT750DC.com

Carb Cleaning on 03 spirit 750 ' Honda Shadow Forums

Carb Adjustments ' Honda Shadow Forums

usually turning screw clockwise sends the main jet down (opening more) getting more fuel through (richer) and opposite is 'usually' for leaner, or 'weaker' mixture...
get hold of a Colourtune carb tuning tool.. this will help endlessly..

As you have not said what machine this is, most carbs will run on a basic setting of one and a quarter turns out on the H and the L screw, you will need to fine adjust from there, they are both fuel, not air screws, so the more you unscrew them the richer the mixture gets, the L screw will adjust the mixture from idle up th.o half throttle, and the h screw will control from half to full throttle including the max rpm.

Hi jbboitnott,

There are 3 things I can think of that would cause that problem. First, the saw was not warmed up enough. Second, did you cut the choke back after your saw warmed up? The third cause would be that your carburetor is not adjusted correctly.
If you did the first two things, then you could try adjusting your carburetor. The carb has to have a richer mixture when it's cold than when it has warmed up. If you have your carburetor set with the mixture too high, it would start but then choke on the extra gas when it was warmed up. Thus, you should lean out the carb.
Huskys carb adjustment screws are on the same side as the oil and gas fill caps. They are above the gas cap. The screw on the left is for leaning the carb, the one on the right is to richen the mixture.
So, turn the left screw, sometimes marked "L", counterclockwise to richen the carb. Adjust a very small amount at a time. Let it run a little, cut some wood, then adjust again, if need be.

I hope this helps. If it does, I'd appreciate your vote. Thanks for visiting fixya.com

Handie Andie

If the screw is on the air filter side of the slide of the carb then it regulates air and screwing it in will make the idle circuit run richer (more fuel, less bleed air). If it is on the engine side of the slide then it regulates fuel and screwing it in will make the idle circuit run leaner (less fuel).

Lightly seat the screws all the way in....then back them out about 1 and 1/2 turns. From there here is how to do the final Zama diaghragm carburetor adjustments.
http://www.zamacarb.com/tipspage.html

If you're talking about simply adjusting the idle mixture screw, you need to turn the screw inwards to lean it out. But, if you can get to the idle mixture screw, your carb has been modified as this screw has a "anti-tamper" plug covering the screw. The mixture screw is on the back side of the float bowl facing upwards.

More than likely, it sounds as if someone has rejetted the carb. That year model CV carb came with a a #42 slow jet in the carb. The modification to make them run better was to go to a #45 slow jet. This was in the original Keihen 40mm CV type carb. You can try to adjust the mixture screw and see if that allows you to pass. If it doesn't, repost and let us know. Maybe we can help you rejet your carb. Good Luck!

Carb.basic setting.
On the Carb to Intake manifold there is an AIR/FUEL volume control screw. Gently screw it in Clockwise until it bottoms out, then back it out 2 turns.
Next, find the Throttle Butterfly Fast/ Slow idling screw, and back it out until the Throttle linkage is released.
Then slowly wind it back in 2 turns
If you have SPARK and FUEL up, then it should Fire Up.
When it does, using the Air/Fuel screw to stabilise the idle mixture, adjust the Idling Speed Screw to run balanced at around 750 RPM.
Happiness!!!
All the best and Regards, DT

Yes, Colorado is much higher in altitude. Do to higher altitude the barometric pressure is less than sea level by a long shot. Lower barometric pressure mean that less air is entering your engine. Which in turns mean that your engine is now running richer than it was at a a lower altitude. So I recommend checking you engine timing, and adjusting your carbs air/fuel mixture. yes this means that you may need to rejet. but first there is a screw on your 22r's carb that you must adjust to lean the air mixture just right. I have had a stock 22r carbortor before and never had to rejet it. i probibly should have but it ran fine at sea level and all the way to about 10000 ft. after 10000 feet i had to lean the fuel mixture to even alow the engine to run. This screw that you must turn is hidden due to toyota not wanting you to tamper with it and burn your engine to the ground by running your engine to lean. it has a metal plug on the passenger side of the carb about the size of a pencil eraser. you must drill that out and then you can adjust the air fuel mixture. Clock wise is to lean the air fuel. and Counter clock wise is to richen the air fuel mixture.A good rule of thumb is to turn the air/fuel screw all the way clock wise and then back out about 2 and 1/2 turns. That is the factory adjustment. you may only need 2 turns out. Best of luck i hope you get it running perfect. Try this adjustment first then if it still runs rich then think about rejetting.

Here is a picture of what i am talking about.

#1 is the air/fuel mixture, #2 and #3 are cold and warm idle screws.
#4 is a A/c idle adjustment.