Q.

What jet size or venturi size do you recommend?

A.

There is no single “correct” jet size or venturi size for every car.

The proper setting depends on many factors, such as:

• Vehicle model
• Engine specifications
• Engine displacement
• Camshaft
• Exhaust system
• Ignition timing
• Fuel type
• Climate and altitude
• Your preferred driving feel (low RPM response, high RPM power, etc.)

Even with the same jet size, the result may change depending on the engine condition, fuel level, synchronization, ignition setting, and many other factors.

Because of this, it is impossible for us to give an exact answer without actual vehicle data and testing.

The standard setup included with the carburetor or kit is only a starting point.

Please install the included parts first and test the vehicle carefully.

From there, adjust step by step by changing:

• Main jets
• Air jets
• Venturi sizes
• Pump system parts
• Other settings

Please repeat trial and error to find the setting that best matches your engine and driving style.

That process is one of the real pleasures of carburetors.

If technical tuning is difficult, we recommend asking a professional tuning shop to help with the setup using the actual vehicle.

We cannot guarantee any specific setting or performance result.

Q.

Idle mixture screw(Pilot screw) precautions
parts list No.61

A.

The tip breaks easily. Do not tighten it too much, but adjust it gently and slowly.

If the tip breaks off, poke it from the other side of the hole with a thin needle-like, approximately 0.8 mm or less in diameter than the hole to remove it.
When doing this, be very careful not to damage the carburetor or other parts.

 Q.

 Can the return spring be made softer?

A softer return spring can make the accelerator pedal feel lighter.

However, if the spring tension is too weak, problems may occur, such as:

• The throttle not fully returning
• Idle RPM not dropping correctly
• Unstable synchronization
• Increased risk of sticking or delayed throttle response

For safety and stable operation, the spring tension must be balanced carefully.

We are also testing softer return spring setups ourselves, but achieving both a light pedal feel and stable throttle return is very difficult.