STIHL Ring - 4243 642 8201

Key Features

• OEM-manufactured sealing ring engineered to STIHL dimensional tolerances for pressurized fuel system integrity.
• Synthetic elastomer compound formulated to resist chemical breakdown from E10 gasoline and 50:1 two-stroke oil formulations.
• Precision-controlled cross-section maintains uniform compression force, preventing vacuum leaks that cause lean-running engine conditions.
• Direct mechanical replacement eliminates adapter hardware or machining during routine maintenance sequences.

Product Details

This genuine STIHL replacement ring is engineered for high-pressure fluid interfaces within carburetor assemblies, fuel pump housings, and cylinder base mating surfaces. The component utilizes a hydrocarbon-stabilized synthetic rubber matrix to prevent accelerated hardening when exposed to modern oxygenated fuel blends. Designed for continuous cyclic compression, the ring retains elastic recovery across standard operating temperature ranges and provides reliable long-term sealing against fuel vapor migration. Installation follows manufacturer torque specifications and surface preparation guidelines detailed in the corresponding operator service manual.

• Manufacturer part designation: 4243 642 8201
• Material classification: Sulfur-free synthetic elastomer rated for petroleum-based hydraulic and fuel environments
• Primary application zones: Carburetor flange gaskets, fuel line pressure couplings, pump diaphragm chamber seals
• Manufacturing protocol: Produced under STIHL quality assurance standards matching original equipment assembly specifications

Compatibility

• MS 250, MS 251, MS 261 chainsaw series
• MS 361, MS 391 professional chainsaw platforms
• FS 38, FS 40, FS 46, FS 56 brushcutter variants
• KMV 56, K 56 cut-off machine engine blocks
• SR 400 leaf blower intake assemblies
• Integrates with complete gasket kit replacements bearing part codes 4243 700 21XX through 4243 700 34XX where factory ring substitution is documented