Regulator Screw Set for 91 120 140 Engines - YSF1251 by YS Engine  [YSF1251]

Product summary and fitment

This regulator screw set serves as a scale RC replacement kit listed for 91, 120 and 140 engine sizes, intended for direct swap where original regulator screws are worn or degraded. The kit targets model engines and their carburetor or regulator attachment points.

Fitment note: the screws match the 91, 120 and 140 size references shown in the product title, so double-check your engine specification before installing. This description keeps to RC use and does not suggest other applications.

Fitting guidance: select the properly sized hex driver, insert screws slowly to avoid cross-threading, tighten to a secure fit without over-torquing, verify linkage alignment after fitting and run the engine gently to confirm stable idle and control response.

Durability benefit: replacing fatigued regulator screws can reduce play in linkages and improve long term consistency of adjustments, supporting cleaner tuning sessions and reduced field maintenance.