MY33-J85 : Sunnen 400 Grit Hone Stones - 3.3 to 4.2" Range
Special stones for ported cylinders. These specially designed stones allow the hone to pass the intake and exhaust ports while maintaining consistent pressure to remove material accurately and easily. Range: 3.3" - 4.2" (83.8 - 106.7mm). Give a 20Ra finish.