BASE ENGINE
ENGINE MECHANICAL11A-8
CONNECTING RODS
The connecting rods are made of highly rigid, forged
carbon steel. The cross section of the rod portion is
shaped like the letter H.
A fracture-split process has been adopted for split-
ting the big end of the connecting rod.
The fracture split connecting rod has the high inser-
tion force between the rod and the cap as well as the
high installation location accuracy.
The oil holes that feed oil from the main journals of
the crankshaft to the crankshaft pins lubricate the
bearings at the big ends of the connecting rods.
CONNECTING ROD BEARINGS
The upper and lower connecting rod bearings are the
same. Each connecting rod bearing is provided with
a backing plate. Its bearing portion is made of an alu
-
minum alloy and its backing plate is made of ordinary
sheet steel.
The width of the connecting rod bearing has been
made as narrow as possible in proportion to the
bearing cap in order to reduce friction loss.
24
AK502491
D
L d
AD
20
ItemSpecifications
Small end hole diameter
(d) mm (in)21 (0.87)
Big end hole diameter (D)
mm (in)51 (2.01)
Center-to-center distance
(L) mm (in)149.25 (5.876)
AK502492AD A
H
Identification
color
ItemSpecifications
Width (H) mm (in)17 (0.7)
Thickness (A) mm (in)1.5 (0.06)
BASE ENGINE
ENGINE MECHANICAL11A-9
CRANKSHAFT
A forged crankshaft has been adopted.
It has 5 main bearings and 8 balance weights.
The crankshaft pins are located at equal 180° inter-
vals.
The oil holes feed engine oil from the journals to the
pins.
A crankshaft sprocket and an oil pump drive shaft are
press-fit to the front of the crankshaft.
CRANKSHAFT BEARINGS, THRUST BEARINGS
The upper crankshaft bearings have oil grooves and
the lower crankshaft bearings do not.
Each crankshaft bearing is provided with a backing
plate. Its bearing portion is made of an aluminum
alloy and its backing plate is made of ordinary sheet
steel. A thrust bearing, which sustains the load in the
thrust direction, is provided at each end of the No. 3
bearing.
AK502493AD
Balance weight
Balance weightBalance weightOil hole
Oil hole
ItemSpecifications
Pin outer diameter mm
(in)48 (1.9)
Journal outer diameter
mm (in)52 (2.0)
AK602940AC
Groove
Front
Thrust bearing
Upper bearingLower bearing
Oil groove
Oil hole
Identification
colorIdentification
color
ItemSpecifications
Crankshaft bearingWidth mm
(in)18 (0.71)
Thickness
mm (in)2.0 (0.08)
Crankshaft thrust
bearingThickness
mm (in)2.0 (0.08)
