See full version: How to Adjust an Evinrude Carburetor
Tell your assistant to reduce the throttle setting to "Idle." Turn the idle speed adjustment screw with a screwdriver until the shop tachometer indicates that the engine is running in the correct r.p.m. range, 1,000 to 1,300. Allow at least 15 seconds between each turn of the idle speed adjustment screw.
Set the shop tachometer to the two-cycle setting. Connect the tachometer to the primary lead for the ignition coil. Tell your assistant to start the motor and run it at half-throttle in "Forward" until it warms up to its normal operating temperature. [links]
Evinrude carburetor adjustments should be made with the motor on the boat and underway. A second boater is required to navigate and control the vessel while you make the adjustments. These adjustments require you to work in close proximity to the engine's moving parts, which poses potential safety risks. Only attempt the adjustments on clear days and in calm waters. more
Confirm the idle speed adjustment is correct by running the engine at various throttle positions. If the engine is running too rich it will "bog down" when the throttle is advanced more than two-thirds throttle, and the idle will be higher than the target idle speed. Since the idle adjustment screw also controls the mixture, readjust the idle speed and repeat the test until the idle speed is correct and the motor no longer "stumbles" during rapid acceleration. more
Shift the motor into forward. The optimum idle speed range for this motor lies between 800 and 900 rpm, with the ideal idle near the center of that range.
Turn the cover locking handle upward and remove the motor cover. Connect the alligator clip of a digital shop tachometer to the motor's no. 1 spark plug. Start the motor and allow it run until it warms to its normal temperature. [links]
There are few adjustments you can make to the carburetor of the 40-horsepower Johnson. It is a single piece, unitized in its construction except for the float bowl and carburetor cover, which are removable. Fuel metering is by a removable jet mounted in the float chamber. The mixture of this single-barrel, float feed-type carburetor is preset at the factory. The motor's idle speed is adjusted using a screw mounted on the side of the carburetor cover, that is jammed in place by a lock nut,. more
Standard slotted screwdriver more
Avoid moving or hot parts. If an adjustment is required, loosen the lock nut on the idle speed screw with a small adjustable wrench and turn the screw clockwise with a standard slotted screwdriver to increase the idle speed or counterclockwise to decrease the idle speed.
Here is the process of the engine.
gaww these 2 strokes are a pain for me.
here is an overview of how two stroke motors work. Two stroke motors are more efficient that four strokes for a few reasons. 1 is the displacement, they generally have smaller combustion chambers, which means less fuel burned. 2 is the fact that they have fewer moving parts, which decreases the constant load on the engine, allowing it to burn the air-fuel mixture more efficiently, and reach much higher revolutions per minute.
You can quickly determine if the spark plugs need to be adjusted by inspecting their color. If it is brown or black, it indicates richness, and if the plugs’ color is dusty white, it means it is burnt, and the mixture is lean. [links]
With the bowls out of the way, you can quickly check out the float levers to see whether all the floats are at the same height or not when the carburetor is held upside down. Check the manual for specified float levels.
Set the carburetor and start the engine. The engine should fire up immediately if the adjustments are correct. Let the engine warm up a bit and set the idle speed. more
These variables will change with the ambient you ride your dirt bike in. So, while adjusting the carburetor mechanism, make sure to keep these three factors in mind.
When the throttle is closed, the tapered needle doesn’t allow the flow from the needle. On the other hand, the needle lets the fuel pass by the taper, needle, and jet wall when it is open. [links]
This vacuum is controlled by the throttle slide cutaway, which measures the height of the upstream bottom edge of the throttle slide. here