Yamaha Fz1n Service Manual

							
CRANKSHAFT
5-73
NOTE:
Identify the position of each crankshaft journal 
upper bearing so that it can be reinstalled in its 
original place.
ET2D1032
CHECKING THE CYLINDER AND PISTON
1. Check: Piston wall
 Cylinder wallVertical scratches  → Replace the cylinder, 
and the piston and piston rings as a set.
2. Measure:
 Piston-to-cylinder clearance
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a. Measure cylinder bore “C” with the cylinder  bore gauge.
NOTE:
Measure cylinder bore “C” by taking side-to-
side and front-to-back measurements of the 
cylinder. Then, find the average of the mea-
surements.
b. If out of specification, replace the cylinder, 
and the pistons and piston rings as a set.
c. Measure piston skirt diameter “P” with the  micrometer. 4 mm (0.16 in) “a” from the bottom edge of 
the piston
d. If out of specification, replace the piston  and piston rings as a set.
e. Calculate the piston-to-cylinder clearance  with the following formula.
f. If out of specification, replace the cylinder,  and the piston and piston rings as a set.
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ET2D1015
CHECKING THE PISTON RINGS
1. Measure: Piston ring side clearance
Out of specification  → Replace the piston 
and piston rings as a set.
NOTE:
Before measuring the piston ring side clear-
ance, eliminate any carbon deposits from the 
piston ring grooves and piston rings.
Cylinder bore “C” 77.00 – 77.01 mm
(3.0315 – 3.0319 in)
Wear limit 77.06 mm (3.03 in)
Taper limit “T” 0.005 mm (0.0002 in)
Out of round “R” 0.005 mm (0.0002 in)
“C” = maximum of D
1 – D6
“T” = maximum of D1 or D2 – maximum 
of D
5 or D6
“R” = maximum of D1 D3 or D5 – 
minimum of D
2 D4 or D6
Piston size “P” 76.975 - 76.990 mm(3.0305 - 3.0311 in)
Piston-to-cylinder clearance = Cylinder bore “C” –
Piston skirt diameter “P”
Piston-to-cylinder clearance0.010–0.035 mm
(0.0004–0.0014 in)
Limit: 0.120 mm (0.0047 in) 
						

							
CRANKSHAFT
5-74
2. Install: Piston ring(into the cylinder)
NOTE:
Level the piston ring into the cylinder with the 
piston crown.
5 mm (0.20 in) “a”
3. Measure:  Piston ring end gapOut of specification  → Replace the piston 
ring.
NOTE:
The oil ring expander spacer’s end gap cannot 
be measured. If the oil ring rail’s gap is exces-
sive, replace all three piston rings.
ET2D1016
CHECKING THE PISTON PINS
The following procedure applies to all of the 
piston pins.
1. Check:  Piston pinBlue discoloration/grooves  → Replace the 
piston pin and then check the lubrication 
system.
2. Measure:  Piston pin outside diameter “a”
Out of specification  → Replace the piston 
pin.
3. Measure:  Piston pin bore inside diameter “b”Out of specification  → Replace the piston.
Piston ring side clearance
Top ring0.030–0.065 mm
(0.0012–0.0026 in)
Limit 0.115 mm (0.0045 in)
2nd ring 0.020–0.055 mm
(0.0008–0.0022 in)
Limit 0.115 mm (0.0045 in)Piston ring end gapTop ring 0.15–0.25 mm
(0.0059–0.0098 in)
Limit 0.50 mm (0.0197 in)
2nd ring 0.30–0.45 mm
(0.0118–0.0177 in)
Limit 0.80 mm (0.0315 in)
Oil ring
0.10–0.40 mm
(0.0039–0.0157 in)
Piston pin bore outside diame-
ter16.991–17.000 mm
(0.6689–0.6693 in)
Limit 16.971 mm (0.6682 in) 
						

							
CRANKSHAFT
5-75
4. Calculate: Piston-pin-to-position clearanceOut of specification  → Replace the position 
pin and piston as a set.
ET2D1017
CHECKING THE BIG END BEARINGS
1. Measure:  Crankshaft-pin-to-big-end-bearing crear-
ance
Out of specification  → Replace the big end 
bearings.
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The following procedure applies to all of the 
connecting rods.
CAUTION:
ECA14900
Do not interchange the big end bearings 
and connecting rods. To obtain the correct 
creankshaft-pin-to-big-end-bearing clear-
ance and prevent engine damage, the big  end bearings must be installed in their orig-
inal positions.
a. Clean the big end bearings, crankshaft 
pins, and the inside of the connecting rods 
halves.
b. Install the big end upper bearing into the  connecting rod and the big end lower bear-
ing into the connecting rod cap.
NOTE:
Align the projections “a” on the big end bear-
ings with the notches “b” in the connecting rod 
and connecting rod cap.
c. Put a piece of Pleastigauge® “1” on the crankshaft pin.
d. Assemble the connecting rod halves.
NOTE:
 Do not move the connecting rod or crank- shaft until the clearance measurement has 
been completed.
 Lubricate the bolt threads with molybdenum 
disulfide grease.
 Make sure that the “Y” mark “c” on the con- necting rod faces towards the left side of the 
crankshaft.
 Make sure that the characters “d” on both the  connecting rod and connecting rod cap are 
aligned.
Piston pin bore inside diameter17.002–17.013 mm
(0.6694–0.6698 in)
Limit 17.043 mm (0.6710 in)
Piston-pin-to-pistonclearance = Piston pin bore size -Piston pin outside diameter
Piston-pin-to-piston clearance
0.002–0.022 mm
(0.0001–0.009 in)
Limit
0.072 mm (0.0028 in)
Crankshaft-pin-to-big-end-bear-
ing clearance 0.034–0.058 mm(0.0013–0.0023 in)
Limit 0.09 mm (0.0035 in) 
						

							
CRANKSHAFT
5-76
e. Tighten the connecting rod bolts.
NOTE:
Install by carrying out the following procedures 
in order to assemble in the most suitable con-
dition.
NOTE:
 First, tighten the bolts to 15 Nm (1.5 m·kg, 11 ft·lb).
 Retighten the bolts to 29.4 Nm (3.0 m·kg, 21 
ft·lb).
f. Replace the connecting rod bolts with new  ones.
g. Clean the connecting rod bolts.
h. After installing big end bearing, assemble  the connecting rod and connecting rod cap 
once using a single unit of the connecting 
rod.
i. Tighten the connecting rod bolt while 
checking that the sections shown “a” and 
“b” are flush with each other by touching 
the surface.
 Side machined face “a”
 Thrusting faces (4 places at front and rear)  “b”
NOTE:
To install the big end bearing, care should be 
taken not to install it at an angle and the posi-
tion should not be out of alignment. j. Loosen the connecting rod bolt, remove the 
connecting rod and connecting rod cap and 
install these parts to the crankshaft with the 
big end bearing kept in the current condi-
tion.
k. Tighten the connecting rod bolts.
CAUTION:
EC2D1014
Tighten the connecting rod bolts using the 
plastic-region tightening angle method.
l. Clean the connecting rod bolts.
m. Tighten the connecting rod bolts.
n. Put a mark “1” on the corner of the con- necting rod bolt “2” and the connecting rod 
“3”.
o. Tighten the bolt further to reach the speci- fied angle (150 ° ).Connecting rod bolt
29.4 Nm (3.0 m·kg, 21 ft·lb)
Connecting rod bolt20 Nm (2.0 m·kg, 14 ft·lb) 
+150 ° 
						

							
CRANKSHAFT
5-77
p. After the installation, check that the section shown “a” is flush with each other by touch-
ing the surface.
 Side machined face “a”
WARNING
EWA13120
 When the bolt is tightened more than the  specified angle, do not loosen the bolt 
and then retighten it.
Replace the bolt with a new one and per-
form the procedure again.
 If they are not flush with each other,  remove the connecting rod bolt and big 
end bearing and restart from step “e”. In 
this case, make sure to replace the con-
necting rod bolt.
CAUTION:
EC2D1015
 Do not use a torque wrench to tighten the nut to the specified angle.
 Tighten the bolt until it is at the specified 
angles.
q. Remove the connecting rod and big end  bearings.
Refer to REMOVING THE CONNECTING 
RODS AND PISTONS on page 5-72.
r. Measure the compressed Plastigauge®  width on the crankshaft pin.
If the crankshaft-pin-to-big-end-bearing 
clearance is out of specification, select 
replacement big end bearings.
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2. Select:
 Big end bearings (P1 – P4)
NOTE:
 The numbers “A” stamped into the crank-shaft wed and the numbers “1” on the con-
necting  rods are used to determine the 
replacement big end bearings sizes.
 “P1” - ”P4” refer to the bearings shown in the 
crankshaft illustration.
For example, if the connecting rod “P
1” and 
the crankshaft web “P
1” numbers are “5” 
and “2” respectively, then the bearing size 
for “P
1” is:
“P1” (connecting rod) – “P1” 
(crankshaft) =
5 – 2 = 3 (brown)
BIG END BEARING COLOR CODE 1Blue
2Black
3Brown
4 Green 
						

							
CRANKSHAFT
5-78
EAS26190
INSTALLING THE CONNECTING ROD AND 
PISTON
The following procedure applies to all of the 
connecting rods and pistons.
1. Install: Top ring “1”
 2nd ring “2”
 Upper oil ring rail “3”
 Oil ring expander “4”
 Lower oil ring rail “5”
NOTE:
Be sure to install the piston rings so that the 
manufacturer’s marks or numbers “a” face up.
2. Install: Piston “1”
(onto the respective connecting rod “2”)
 Piston pin “3”
 Piston pin clip “4”  
NOTE:
 Apply engine oil onto the piston pin.
 Make sure that the “Y” mark “a” on the con- necting rod faces left when the arrow mark 
“b” on the piston is pointing up as shown.
 Reinstall each piston in to its original cylinder 
(numbering order starting from the left: #1 to 
#4).
3. Lubricate: Piston
 Piston rings
 Cylinder (with the recommended lubricant)
4. Offset:  Piston ring end gaps
5. Lubricate:  Crankshaft pins
 Big end bearings
 Connecting rod big end inner surface(with the recommended lubricant)
6. Check:  Cylinder stud bolts “1”
7. Install:  Cylinder gasket “2” 
Recommended lubricantEngine oil
a. Top ring
b. Lower oil ring rail
c. Upper oil ring rail
d. 2nd ring
e. Oil ring expander
Recommended lubricantEngine oil
Cylinder stud bolt8 Nm (0.8 m·kg, 5.8 ft·lb) 
						

							
CRANKSHAFT
5-79
8. Install: Big end bearings(onto the connecting rods and connecting 
rod caps)
NOTE:
 Align the projections “a” on the big end bear-ings with the notches “b” in the connecting 
rods and connecting rod caps.
 Be sure to reinstall each big end bearing in 
its original place.
 Make sure that the characters “c” a on both  the connecting rod and connecting rod cap 
are aligned.
9. Tighten:  Connecting rod bolts
NOTE:
 Install by carrying out the following proce-
dures in order to assemble in the most suit-
able condition.
 First tighten the bolts to 15 Nm (1.5 m·kg, 11  ft·lb)
 Retighten the bolts to 29.4 Nm (3.0 m·kg, 21 
ft·lb)
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a. Replace the connecting rod bolts with new  ones.
b. Clean the connecting rod bolts.
c. After installing the big end bearing, assem- ble the connecting rod and connecting rod 
cap once using a single unit of the connect-
ing rod.
d. Tighten the connecting rod bolt while  checking that the sections shown “a” and 
“b” are flush with each other by touching 
the surface.
NOTE:
To install the big end bearing, care should be 
taken not to install it at an angle and the posi-
tion should not be out of alignment.
e. Loosen the connecting rod bolt, remove the connecting rod and connecting rod cap and 
install these parts to the crankshaft with the 
big end bearing kept in the current condi-
tion.
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10. Install:
 Piston assemblies “1”(into the cylinder)
NOTE:
While compressing the piston rings with one 
hand, install the connecting rod assembly into 
the cylinder with the other hand.
Connecting rod bolt
29.4 Nm (3.0 m·kg, 21 ft·lb)
a. Side machined face
b. Thrusting faces (4 places at front and rear) 
						

							
CRANKSHAFT
5-80
11. Install: Cylinder assembly “1”
 Connecting rod caps “2”
NOTE:
 Make sure that the “Y” marks “a” on the con-necting rods face towards the left side of the 
crankshaft.
 Make sure that the characters on both the  connecting rod and connecting rod cap are 
aligned.
12. Tighten:  Connecting rod bolts
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CAUTION:
ECA14980
Tighten the connecting rod bolts using the 
plastic-region tightening angle method.
a. Clean the connecting rod bolts.
b. Tighten the connecting rod bolts.
c. Put a mark “1” on the connecting rod bolt  “2” and the connecting rod cap “3”.
d. Tighten the bolt further to reach the speci- fied angle (150 °).
e. After the installation, check that the section  shown “a” is flush with each other by touch-
ing the surface.
WARNING
EWA13990
 When the bolt is tightened more than the 
specified angle, do not loosen the bolt 
and then retighten it. Replace the bolt 
with a new one and perform the proce-
dure again.Connecting rod bolt20 Nm (2.0 m·kg, 14 ft·lb)+150 °
a. Side machined face 
						

							
CRANKSHAFT
5-81
 If they are not flush with each other, remove the connecting rod bolt and big 
end bearing and restart from step “9”. In 
this case, make sure to replace the con-
necting rod bolt.
CAUTION:
ECA14680
 Do not use a torque wrench to tighten the 
bolt to the specified angle.
 Tighten the bolt until it is at the specified 
angles.
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ET2D1018
CHECKING THE CRANKSHAFT
1. Measure:  Crankshaft runout
Out of specification  → Replace the crank-
shaft.
2. Check:  Crankshaft journal surfaces
 Crankshaft pin surfaces
 Bearing surfacesScratches/wear  → Replace the crankshaft.
ET2D1019
CHECKING THE CRANKSHAFT DRIVE 
SPROCKET
1. Check:
 Crankshaft drive sprocket “1”Cracks/damage/wear  → Replace the 
defective part(s).
ET2D1020
CHECKING THE CRANKSHAFT JOURNAL 
BEARINGS
1. Measure:
 Crankshaft-journal-to-crankshaft-journal-bearing clearance
Out of specification  → Replace the crank-
shaft journal bearings.
CAUTION:
EC2D1008
Do not interchange the crankshaft journal 
bearings. To obtain the correct crankshaft-
journal-to-crankshaft-journal-bearing clear-
ance and prevent engine damage, the 
crankshaft journal bearings must be 
installed in their original positions.
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a. Clean the crankshaft journal bearings,  cranshaft journals, and bearing portions of 
the crankcase.
b. Place the upper crankcase upside down on  a bench.
c. Install the crankshaft journal upper bear- ings “1” and the crankshaft into the upper 
crankcase.
NOTE:
Align the projections “a” on the crankshaft jour-
nal upper bearings with the notches “b” in the 
upper crankcase.
Crankshaft runoutLess than 0.03 mm (0.0012 in)
Crankshaft-journal-to-crank-
shaft-journal-bearing clearance0.014–0.037 mm
(0.0006–0.0015 in)
Limit 0.10 mm (0.0039 in) 
						

							
CRANKSHAFT
5-82
d. Put a piece of Plastigauge® “2” on each crankshaft journal.
NOTE:
Do not put the Plastigauge® over the oil hole in 
the crankshaft journal.
e. Install the crankshaft journal lower bear-ings “1” into the lower crankcase and 
assemble the crankcase halves.
NOTE:
 Align the projections “a” of the crankshaft 
journal lower bearings with the notches “b” in 
the lower crankcase.
 Do not move the crankshaft until the clear-
ance measurement has been completed.
f. Tighten the bolts to specification in the  tightening sequence cast on the crankcase. M9 x 105 mm (4.1 in) bolts: “1”–“10”
M8 x 60 mm (2.4 in) bolt: “11” LOCTITE®
M8 x 60 mm (2.4 
in) bolts: “12”, “16”
M6 x 70 mm (2.8 in)  bolts: “19”, “21”, “23”
M6 x 65 mm (2.5  in) bolts: “17”, “18”
M6 x 60 mm (2.4 in) bolt and washer: “22”
M6 x 60 mm (2.4  in) bolts: “24”, “25”
M6 x 50 mm (2.0  in) bolts: “20”, “26”
M8 x 50 mm (2.0 in) bolts: “13”–“15”
* Following the tightening order, loosen the 
bolt one by one and then retighten it to the 
specific torque.
NOTE:
Lubricate the crankcase bolt threads with 
engine oil.
Refer to CRANKCASE on page 5-66.
g. Remove the lower crankcase and the  crankshaft journal lower bearings.
h. Measure the compressed Plastigauge® 
width “c” on each crankshaft journal.
If the crankshaft-journal-to-crankshaft-jour-
nal-bearing clearance is out of specifica-
tion, select replacement crankshaft  journal 
bearings.
Crankcase boltBolt “1”–“10”
1st: 20 Nm (2.0 m·kg, 14 ft·lb)
2nd: 20 Nm (2.0 m·kg, 14 ft·lb)
3rd: +60 °
Bolt “11”–“16”
 24 Nm (2.4m·kg, 17 ft·lb)
Bolt “17”–“26”
 12 Nm (1.2m·kg, 8.7 ft·lb)