S-25 Silencer O-ring OS42525310 Replacement for RC Mufflers by O.S. Engine  [OS42525310]

How the S-25 Gasket Affects Engine Performance

The S-25 silencer gasket supplied by O.S. Engine is intended as a single replacement O-ring for silencers that use the S-25 profile. Associated references include F-6020 and FSa-155; the ring restores a sealed joint at the silencer to reduce blow-by and help maintain intended exhaust flow.

Installation is direct: detach the silencer, clear any carbon or burrs from the mating face, seat the O-ring neatly into its channel, and refit ensuring the seal is compressed evenly. Avoid twisting during installation and check the connection under low rpm to confirm there is no leakage.

A correctly installed silencer gasket helps keep backpressure consistent at the exhaust outlet, which can improve idle stability and throttle response for tuned glow engines. Replace the ring if it becomes stiff, cracked, or misshapen as part of regular maintenance.