Piston Ring OS29203400 for O.S. Engine 108FSR and 105HZ  [OS29203400]

Application and service notes for piston rings

This replacement piston ring is intended for RC engines identified as 108FSR and 105HZ and is catalogued under the O.S. Engine OS29203400 part number. The text emphasises fitment verification, installation care, and the ring's contribution to engine maintenance without making unverified material or manufacturing claims.

A piston ring's role is to re-establish the seal between piston and cylinder to recover compression and limit blow-by. When fitting a replacement, ensure the ring profile suits the piston groove and that the end gap falls within the engine manufacturer's specified range, as incorrect clearance will alter compression and idle stability.

Installation advice: assemble on a clean bench, lightly lubricate the ring and piston with an appropriate glow-engine oil, and turn the crank slowly to check for free operation before finishing the build. Check for cylinder or ring scoring to decide if a ring alone is sufficient or if further engine work is necessary.

Tuning impact: replacing a worn ring can improve compression stability and refine throttle response, offering more predictable engine performance during setup and fine-tuning.