Zama High Speed Adjustment Screw for Carburetor

The Zama High Speed Adjustment Screw is a carburetor mixture screw, also called a high speed needle, H screw or high speed mixture screw. It lets you fine-tune the fuel mixture your engine gets at high RPM and under load. Zama carburetors are used on many two-stroke outdoor power tools, including chainsaws, string trimmers, leaf blowers and edgers.

Key Features:

• Controls the high speed fuel circuit, usually marked "H" on the carburetor body
• Lets you dial in full-throttle fuel delivery for smooth, consistent power
• Replaces a worn, damaged or seized adjustment screw to restore proper tuning
• Made by Zama, a well-known name in small engine carburetors
• Adjusts with a standard screwdriver or the appropriate tuning tool

Tuning Notes:

• Turn the screw gently, and do not over-tighten it. Forcing it can damage the screw seat or needle.
• Make small adjustments and let the engine settle after each one.
• A lean high speed setting can damage the engine, so keep full-throttle running time short while tuning.
• Refer to the equipment manual for factory settings and maximum RPM.

Choose the correct child item for your specific carburetor to get the right screw for your application.