Crankshaft; Piston And Piston Rings - wsm BX1800 Workshop Manual

BX1800 · BX2200, WSM

[3] CRANKSHAFT

[4] PISTON AND PISTON RINGS

The crankshaft with the connecting rod converts the
reciprocating motion of the piston into the rotating
motion.
The crankshaft is made of tough special alloy steel,
and the journals, pins and oil seal sliding portions are
induction hardened to increase the hardness for higher
wear resistance.
The front journal is supported by a solid type bearing,
the intermediate journal by a split type, and the rear
journal by a split type with thrust bearings.
The crankshaft is provided with an oil gallery, through
which engine oil is fed to the crankpin portion, and
lubricate it.
The piston has a slightly oval shape when cold (in
consideration of thermal expansion) and a concave
head.
Three rings are installed in grooves in the piston.
The top ring (1) is a keystone type, which can stand
against heavy loads, and the barrel face on the ring fits
well to the cylinder wall.
The second ring (2) is an undercut type, which
effectively prevents the oil from being carried up.
The oil ring (3) has chamfered contact faces and an
expander ring, which increase the pressure of the oil ring
against the cylinder wall.
Several grooves are cut on the top land to help heat
dissipate and to prevent scuffing.
(1) Top Ring
(2) Second Ring
(3) Oil Ring
1-M3
ENGINE
W1012847
(4) Depression
(5) Valve Recess
W1013119
KiSC issued 07, 2006 A