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How to tune honda Cd70 Euro2 Idle mixture

honda cd70 red

The Honda CD70 Euro2 carburetor is equipped with an air screw for adjusting the idle mixture. The optimal method for adjusting the carburetor's idle mixture involves delicately balancing the air-fuel mixture within the provided adjustment range.

carburetor engine side profile

Front or engine side

carburetor adjustment side

Adjustment Screw Side

carburetor air filter side

Air Filter Box Side

Step 1: To adjust the idle speed to 1500 rpm, utilize the idle screw. Turn the screw clockwise to increase the engine RPM and counterclockwise to decrease it.

carburetor rpm adjuster screw turn left

Turn Left to decrease the Engine Rpm

carburetor rpm screw turn right

Turn Right to Raise the Engine Rpm

air fuel adjustment Air Screw

Idle Mixture Adjustment Screw in this case ( Air Screw)

Step 2:

Begin by turning the idle air mixture screw left by 1 and a half turns to adjust it to the factory setting.

Next, starting from this position, gradually turn the screw a quarter turn to the right, pausing each time to check if the engine RPM decreases.

Once you observe a decrease in engine RPM, take note of this point.

Then, turn the adjustment screw to the left until the RPM begins to stumble or become irregular.

Finally, set the adjuster screw between these two points where the engine stumbles or the RPM starts to decrease.

For example :

At one turn, you'll notice the engine RPM starting to decrease. By two turns, the RPM begins to get irregular. At two and a half turns, that's the sweet spot where the idle mixture screw should be set.

idle adjustment screw

Idle Adjustment Screw

Step 3: Following the adjustment of the air mixture screw, fine-tune the RPM using the idle RPM screw until it reaches 1500 RPM.

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