Piston for 61ST-H Side-Exhaust Engines YSS7106 - YS Engine  [YSS7106]

61ST-H compatible side-exhaust piston

This item is a replacement piston produced to the 61ST-H pattern for side-exhaust RC engines. Provided by YS Engine as a spare, it is intended for use when performing routine service or rebuilding compatible 61ST-H side-exhaust engine units.

Role and fit: the piston is the reciprocating part inside the cylinder that, together with the sleeve, piston ring and conrod, completes the combustion cycle in side-exhaust designs. Fit a new piston if inspection shows wear, scoring or a drop in compression.

Installation notes: piston replacement requires removing the cylinder sleeve and disconnecting the connecting rod to access the wrist pin. Thoroughly clean mating surfaces, follow correct lubrication practice during reassembly, and use standard small-engine service techniques. Seek professional help if uncertain about the process.

Tuning and maintenance context: installing a new piston helps restore compression uniformity and stabilises power output; always pair piston replacement with checks on the sleeve, ring condition and port timing for consistent engine behaviour.