YS Engine YSS9121 Throttle Barrel 91SR Replacement Part  [YSS9121]

YS Engine YSS9121 Throttle Barrel Overview

This YS Engine YSS9121 throttle barrel is a purpose-built replacement for 91SR model engines. It functions as the throttle slide within the carburetor, controlling airflow and influencing throttle response during both tuning sessions and normal running.

This item is intended for 91SR engines as shown by the designation. Prior to fitting, verify that the carburetor body and throttle linkage on your model match the physical size and mounting of the existing throttle barrel to ensure correct movement and clearance.

Installation notes: remove the carburetor from the model, inspect mating surfaces, and transfer the throttle slide carefully to preserve orientation. Reassemble and check that the throttle linkage moves smoothly through the full travel without binding. You may need small linkage or idle adjustments after replacement to recover the desired idle and full-throttle behavior.

Tuning role: the throttle barrel has a direct effect on idle stability and transient throttle response; replacing a worn or damaged barrel helps restore consistent airflow and simplifies carburetor tuning. Regular inspection and gentle cleaning of the barrel and bore will maintain predictable operation.