Wake up your saw with precision CNC porting from 309 Machine. Our focus is simple: maximize power while maintaining the reliability and durability professionals expect. The HP400 Cylinder Kit represents the ideal balance of high performance and longevity, delivering increased torque and horsepower along with improved throttle response and cutting performance. What’s Included • Brand new OEM Stihl Cylinder Kit • Stihl Part Number 1140-020-1212 • OEM cylinder • OEM piston • Piston rings • Piston Wrist Pin • Circlips• 309 Machine Decomp Plug Base gasket must be reused or replaced. Gaskets are sold separately. We recommend using a piston ring clamp set when installing a new cylinder. Performance Work Includes • CNC cylinder porting• Exhaust port enlargement, timing, and polishing• Squish band machining for improved combustion efficiency• Base cut for increased compression• Transfer port adjustments and flow optimization• Intake port timing Perfect for refreshing a tired saw or for those who want ported performance without long lead times. These units are in stock and ready to ship. For maximum performance, we recommend pairing this cylinder with a performance exhaust and high flow air filter. Fitment • Stihl MS 400
