See full version: How to Adjust Motorcraft 2 Barrels
Turn the idle mixture adjustment screws on the front of the carburetor 1/4th of a turn at a time, alternating back and forth until they reach the highest reading possible on the vacuum gauge while maintaining the optimum smoothness. here
Turn the two idle mixture adjustment screws clockwise with a screwdriver until they stop. Do not over-tighten the screws. Turn both screws back 1 1/2 turns counterclockwise to have an even start point for adjusting the Motorcraft 2 barrel carburetor. more
Start the motor and let it warm up until you see the choke plate inside the carburetor open up. Remove the rubber vacuum hose from the vacuum port on the front of the carburetor and attach the vacuum gauge to the port.
Put the vehicle in "Park" and readjust the idle mixture screws in the front to the highest vacuum reading with the optimum smoothness. Both screws should be adjusted within a 1/4th of a turn of each other. [links]
Adjusting the Motorcraft 2 barrel carburetor to the proper settings will provide you with more performance and better fuel mileage. The Motorcraft 2 barrel carburetor has two idle mixture adjustment screws on the front near the base, and an idle speed adjustment screw next to the choke cable. The carburetor can be adjusted with some basic tools in just a few minutes, keeping the engine running properly and helping to extend the life of the motor.
Inspect the carburetor's linkage and choke. Be sure it was installed correctly and operates as intended. Replace the air cleaner, connect its vacuum hoses and secure it to the carburetor by hand with its wing nut. more
Correct the idle speed with the idle-speed screw after you adjust idle mixture. It is located at the bottom left hand corner on the driver's side of the carburetor. Turn it with your screwdriver until engine rpm is where it was before adjusting the left idle-mixture screw. [links]
Write down the current rpm of the engine at idle. Move to the front of the engine to adjust the left idle-mixture screw with your flat-head screwdriver. Turning the screws in (clockwise) leans the mixture, and turning them out (counterclockwise) makes it richer. Your goal is to increase the rpm with this adjustment. Stop adjusting when the highest rpm is reached. [links]
Insert the screwdriver into the idle-mixture screw on the right. Turn the idle-mixture screw to increase rpm. Increase rpm as high as it will go with this adjustment. Correct the engine idle again with the idle-speed screw.
Tuners are often confused when it comes to being able to identify whether a particular adjusting screw on a carb is a fuel screw (that adjusts low speed fuel delivery) or an air screw (that adjusts low speed air delivery). Carb accessory guru Lonn Peterson at Thunder Products tells us that generally, if the adjustment screw is on the engine side of the carb slide it is a fuel screw and thus can be used to fine tune low speed fuel delivery. If the adjustment screw is on the airbox side of the carb, then it is (generally) an air screw and is used to fine tune the low speed air delivery. On most carbs found on late model sleds, this seems to be fairly consistent. [links]
This is helpful to know, as (generally) turning an airscrew out adds more air (a leaner mixture) and turning a fuel screw out adds more fuel (richer mixture). Knowing which is which and what happens when you crank it this way or that aids in off-throttle performance (as the engine comes off idle) and low speed operation, as well as idle stability. Many riders use this adjustment to maintain a crisp throttle response, especially as riding conditions (elevation, temperature, barometer) vary. more
Hey Bill – Thanks for the info! That rubber cap, part #27, has gotten so hard, I thought it may be rubber coated steel. The hardness of it may be causing it to bind up on the brass part #23 that has to slide through it. here
I’ll see if it runs tomorrow!
Dave
Although the manual shows the choke assembly disassembled, it does not have specific wording on how to do it. #27 is a “rubber cap” and under that, is #26, the retaining clip. Prying off the rubber cap seems a safe bet. more
I noticed a subtle thing about the design of the carb. It appears that each time you use the choke, a small amount of gas/oil mix stays behind to lubricate the choke’s piston where it slides in the carb body. here
I got it together and got the binding choke working – several issues there, some because somebody else messed it up worse. [links]