HP661C

The HP661C is the ultimate mix of power and durability.

HP stands for High Performance, and that's what we are all about. We strive to maximize power while focusing on durability and reliability.

This is for the Power Head Only (PHO).

Performance work includes;

• CNC Cylinder porting
  • Exhaust Port enlargement, timing and polishing
  • Intake Port enlargement, timing and texturing
  • Squish band cut for smaller combustion area
  • Base cut for increased compression
• Port matching, baffle thinning and hole enlargement on muffler
• 309 Machine Decompression Plug Install
• Undaunted Manufacturing Billet Muffler Cover

Independently modified — not a factory STIHL® product.

This saw is built on a genuine STIHL® MS 661 powerhead that has been independently CNC-ported and modified by 309 Machine, LLC. It is sold as a performance-modified product, not as a new, factory-original saw. 309 Machine is not affiliated with, authorized by, endorsed by, or sponsored by STIHL. STIHL® is a registered trademark of ANDREAS STIHL AG & Co. KG and is used here for identification and descriptive purposes only. Modification voids any original manufacturer warranty; any warranty or support for this product is provided solely by 309 Machine. See our Product Liability Disclaimer for full terms.