Piston, Engine

Pistons
General data
Mean piston speed at 5000 rpm
B205 13 m/s
B235 15 m/s

Important: Different makes of piston must not be fitted in the same engine.

Piston types

Classification of pistons and cylinder bores
The piston classification is stamped on the piston crown roof. The piston classes for service are B
First oversize (+0.5)
Second oversize (+1.0)

Piston classification
AB 89.964 - 89.975 mm
B 89.975 - 89.982 mm
First oversize (+0.5) 90.457 - 90.475 mm
Second oversize (+1.0) 90.957 - 90.975 mm
Piston clearance, nominal 0.025 - 0.056 mm

Piston diameter
Piston diameter is measured at right angles to the gudgeon pin holes, 11 mm from the bottom of the piston.

Gudgeon pins
Diameter 23.996 - 24.000 mm
Clearance, gudgeon pin/connecting rod bush 0.012 - 0.021 mm
Length 63 mm

A/B piston fits both A and B cylinder bores 90.000 - 90.020 mm
B piston 90.007 - 90.020 mm
Permitted piston clearance 0.025 - 0.056 mm