STIHL Piston ring 42370343001 / 4237 034 3001

Overview:
This piston ring is a Genuine Stihl part for maintaining engine compression in small 2‐stroke machines. Made from wear‐resistant steel to Stihl's specification, it replaces a worn ring to restore sealing between the piston and cylinder, helping the engine start reliably and deliver steady power. Supplied under Manufacturer Part Number (MPN) 4237 034 3001, it is designed for Stihl handheld equipment such as blowers and hedge trimmers, including the BG 56 and BG 86. A sound piston ring reduces blow‐by, limits oil contamination, and supports cleaner running, making it suitable for routine maintenance or a top‐end refresh after inspection. As a genuine component, it matches the original dimensions for correct fit and function in compatible Stihl machines.

Key Features:
- Genuine Stihl part (MPN 4237 034 3001) for assured fit and performance
- Maintains correct compression and sealing for easier starting and consistent power
- Durable steel construction for long service life in high‐temperature, high‐load use
- Helps restore throttle response and overall engine efficiency when a ring is worn
- Accurate sizing for proper end gap and smooth operation in the cylinder bore
- Straightforward to fit with standard workshop tools during a top‐end service
- Suitable for Stihl 2‐stroke engines used in blowers, hedge trimmers, chainsaws, and mistblowers
- Supports preventive maintenance schedules to extend engine life and reduce downtime

Typical Applications:
Used when compression loss is suspected or confirmed, such as hard starting, reduced power, or poor idle. Ideal during routine decoke and inspection of the top end, or when replacing a scored piston and cylinder set. Common in servicing Stihl handheld tools used for garden, landscaping, grounds care, and light construction site clean‐up.

Also known as:
Engine ring, cylinder sealing ring, top ring, piston sealing ring, motor ring, compression sealing ring.

Fits Models:
BG 56, BG 86, BR 200, HS 45, HS 82, HS 87, MM 56, MM 56 MultiSystem, MS 151 C, MS 151 TC, SH 56, SH 85, SH 86, SR 200, SR 200-Z