Generally the AFR screw will adjust the amount of fuel and so turning the screw in will reduce the amount of fuel and therefore weaken the mixture.
Some carbs have an idle air screw and it as well to be aware of this even though it isn't likely to be encountered with motorcycles/small engines. An air screw tends to be physically bigger and turning it in will slow the idle speed and weaken the idle mixture.
This design of carb tends to be used where stringent emission control is required. Very cheaply made carbs of this type often do not have a fuel screw but better quality carbs usually have a fuel screw that is factory preset and sealed.
That direction should be lean
SOURCE: Repair manual for mcculloch B320 blower
The hose with the filter in the tank is the pick up, the other is return. the pick up is usualy goes towards the middle pipe on the carby. if you get them around the wrong way it wont pick of fuel..
Screw the mixtures in untill they just bottom and screw them out 1 to 1.5 turns start up set low mix untill its just "four stroking" the set the high.
SOURCE: "L" adjustment screw on the carburator
L is for idle speed mixture and H is for full throttle mixture. Adjust H, when engine is warmed up, with full throttle--adjust for high speed, but 4-stroking which should smooth out just as soon as you start cutting. Allow to idle and adjust L for smooth idle, but rich enough to allow the engine to 'follow the throttle'. Set idle speed screw to just allow the chain to stop moving.
SOURCE: i have a 27499-85 carburetor on a 1979 harley
This is not the original carburetor that came on the bike. The orignial was a Kehien "butterfly" carburetor. This carburetor is a later "CV" version with the large square looking top on it.
I'll tell you how to access the idle mixture screw on each model. The "butterfly" carb had it's idle mixture screw in a "tower" on top of the carb just forward of the carburetor mounting flange. The square topped "CV" carb has the idle mixture screw underneath the carb at rear of the float bowl.
They both came from the factory with an "anti-tamper" plug of about 3/16 inch diameter (5mm) pressed in over the adjuster screw so that the owner could not mess with the idle mixture.
To get access to the idle mixture adjustment screw, you must drill a small hole in the "anti-tamper" plug. Be very careful not to drill too deeply or you will damage the brass screw underneath the plug. Drill just enough to go through the plug with a small drill bit. Screw a sheet metal screw or start a tap in the hole. If you use the sheet metal screw, use a pair of pliers or something to pull the plug out. If you're using a tap, once you get the hole tapped screw a screw into the hole and use the pliers to pull the plug out.
If your bike will idle at all, start the bike up and allow the engine to warm up. If it won't idle, screw the idle mixture in until it just barely "bottoms" in the hole. Back it out 1 1/2 turns on the "butterfly" carb and about 3 turns on the "CV" carb and start the engine. Adjust the screw to obtain the highest smoothest idle. Then use the throttle stop screw to set the idle speed of the engine. Once you're finished, put a small dab of RTV sealant in the hole over the screw. If you don't do this, water will seep down by the fine threads permanently seizing the screw making it impossible to adjust the idle mixture in the future.
Testimonial: "i'll pull the carburetor and she if the plug is where you said it should be. i'll let you know if this does the trick."
SOURCE: how do i adjust the rich/lean fuel mixture cracked intake
You can't do it with out a tech 2 scanner, so your going to have to go back to the Mechanic to have it reprogrammed. As long as it's running rich, your going to have bad fuel economy and will not pass the emission test when you have to have it done. Good luck and glad to know you got your car running almost 100%
SOURCE: 1997 jeep cherokee, check engine light on,
o2 sensor: or you have stopped up injectors or a vaccum leak or egr valve sticking
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