BB-86 Counterbore Unit - Fully Portable and Simple to Operate

The BB-86 is a fully portable and simple to operate tool to recut Diesel sleeve counterbores.To guarantee a perfect seal between engine block and wet liners, the counterbore seat of an engine block must be refaced during engine overhaul and in case of leaks. This job is rapidly and simlpy carried out with the accurate BB-86 unit which fits and centers directly on the engine block. Its centering is automatic and the unit is clamped by means of a strong electro magnet. As the unit is placed directly on the sealing surface of an engine block, the reface counterbore seats will automatically be parallel with the sealing surface. The refacing procedure can be carried out on installed as well as on removed engine blocks or even built-in underfloor engines.


Following individual MIRA BB-86 units are available:

  • BB-86 Mini              (154mm inside magnet diameter)
  • BB-86 Standard     (170mm inside magnet diameter)
  • BB-86 Giant            (198mm inside magnet diameter)
  • BB-86 Extension    (Up to 200mm in depth.Complete Kit)


The BB-86 unit includes

  • BB-86 unit
  • turning handle
  • service tooling (screw drivers)
  • Instruction manual
  • wooden storage box


Standard MIRA cutting tool range

Cutting tools Bore diameters in mm
MB85 73.00 - 86.00mm
MB86 85.00 - 104.00mm
MB87 97.00 - 126.00mm
MB88 123.00 - 160.00mm
MB88DAF 123.00 - 162.00mm
MB88AD 130.00 - 166.00mm
MB89* 158.00 - 194.00mm
MB136 105.00 - 130.00mm
MB137 130.00 - 160.00mm
MB138 160.00 - 190.00mm
MB139 190.00 - 220.00mm
MIRA BB Katalog 201708
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