Example B - Mira BB-86 Mini Instruction Manual

Sealing shim

3.2 Example B

If an engine is only partially dismounted or only one counterbore needs work, the situation changes. In such
a case the block is not re-surfaced. Instead, the leaky sleeve has to be replaced by an oversized sleeve, or
a sealing sheet needs to be applied to the standard sleeve. The correct counterbore depth must be
determined by either the thickness of the sealing sheet, or the oversized collar.
If only one counterbore needs to be repaired, a repair centering ring is available to simplify the procedure.
The repair centering ring compensates for the protrusion of the neighboring sleeves (see „Special
accessories" on page 36). The picture shows the important surfaces to be worked on. These include the
sealing surface for the cylinderhead and also the sealing and bearing surface for the sleeve collar. The
sleeve should be set according to the specifications of the engine manufacturer. The sleeve can be recessed
instead of protruding.
19 July 2023/v1.7
Protrusion
Counterbore-Ø
BB-86 | Serial-No. 865 / 0609 ©
Engine
block
17
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