Benelli ZAFFERAN 250, Service Manual

Page: 132 / 187

132
15.
Crankcase
Preparation documents-------------------15.1
Failure diagnosis---------------------------15.2
Crankcase-----------------------------------15.3
15.1
Preparation Documents
Function of the crankcase:
The crankcase is the force-bearing part of the engine. Its main
function is bearing crankshaft, clutch, transmission case, cylinder body and cylinder head, bearing
the inertia force from combustion shock and the movement of crankshaft connecting rod system,
and forming a closed space (oil sealing, gas sealing).
There are suspension holes in the crankcase, connecting the engine to other parts of the body
through the connection with suspension holes in the car circuit
Notes
The crankcase is thin-section casting thus has to avoid shock on operation in case of deformation
and fracture. All components must be cleaned and dried with high-pressure air before testing.
The lubricant in the crankcase should be drained before operation.
Preparation standard
unit
：
mm
Item Standard value Usage limit
Crankshaft
Left-right clearance of rod big end
0.5-0.75 0.9
Radial clearance of rod big end
0.008-0.018 0.05
Shimmy
0.03 0.09
15.2
Failure diagnosis
Noise in crankcase
Loose or broken parts inside crankcase
Loose crankshaft pin bearing