Yamaha Fz6 N Service Manual

							
CRANKSHAFT
5-70
9. 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 corner of the con-
necting rod bolt “2” and the connecting rod 
cap “3”.
d. Tighten the bolt further to reach the speci- fied angle (120 °).
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.
 If they are not flush with each other,  remove the connecting rod bolt and big 
end bearing and restart from step “7”. In 
this case, make sure to replace the con-
necting rod bolt.
CAUTION:
ECA4S81029
 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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EAS4S81038
CHECKING THE CRANKSHAFT
1. Measure:  Crankshaft runout
Out of specification  → Replace the crank-
shaft.
2. Check:  Crankshaft journal surfaces
 Crankshaft pin surfaces
 Bearing surfaces Scratches/wear  → Replace the crankshaft.
EAS4S81039
CHECKING THE CRANKSHAFT JOURNAL 
BEARINGS
1. Measure:
 Crankshaft-journal-to-crankshaft-journal  bearing clearance
Connecting rod bolt15 Nm (1.5 m·kg, 11 ft·lb) + 
120 °
a. Side machined face
Crankshaft runout
Less than 0.03 mm (0.0012 in) 
						

							
CRANKSHAFT
5-71
Out of specification → Replace the crank-
shaft journal bearings.
CAUTION:
ECA4S81028
Do not interchange the crankshaft journal 
bearings. To obtain the correct crankshaft 
journal- to-crankshaft-journal-bearing 
clearance 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, 
crankshaft 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.
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.
*Loosen the bolts following the tightening 
order and then tighten to specification 
torque.
NOTE:
Lubricate the crankcase bolt threads with 
engine oil.
Crankshaft-journal-to-crank-
shaft journal bearing clearance0.028–0.052 mm 
(0.0011–0.0020 in)
Crankcase boltBolt “1”–“10”
1st: 12 Nm (1.2 m·kg, 8.7 ft·lb)
2nd: 25 Nm (2.5 m·kg, 18 ft·lb)
3rd*: 27 Nm (2.7 m·kg, 20 ft·lb)
Bolt “11”, “12”
24 Nm (2.4 m·kg, 17 ft·lb)
Bolt “13”, “14”
14 Nm (1.4 m·kg, 1.0 ft·lb)
Bolt “15”–”27”
12 Nm (1.2 m·kg, 8.7 ft·lb) 
						

							
CRANKSHAFT
5-72
Refer to CRANKCASE on page 5-55.
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.
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2. Select: Crankshaft journal bearings (J1–J5)
NOTE:
 The numbers “A” stamped into the crank-shaft web and the numbers “1” stamped into 
the lower crankcase are used to determine 
the replacement crankshaft journal bearing 
sizes.
 “J1–J5” refer to the bearings shown in the 
crankshaft illustration.
 If “J1–J5” are the same, use the same size  for all of the bearings.
 If the size is the same for all “J
1 to J5” one 
digit for that size is indicated. (Crankcase 
side only) For example, if the crankcase “J
1” and 
crankshaft web “J
1” numbers are “6” and 
“2” respectively, than the bearing size for 
“J
1” is:
EAS4S81040
INSTALLING THE CRANKSHAFT
1. Install:  Crankshaft journal upper bearings “1” (into the upper crankcase)
“J1” (crankcase) – “J1”
(crankshaft web) – 1 =
6 – 2 – 1 = 3 (brown)
CRANKSHAFT JOURNAL BEARING  COLOR CODE
0 White
1Blue
2Black
3Brown
4 Green 
						

							
CRANKSHAFT
5-73
NOTE:
 Align the projections “a” on the crankshaft journal upper bearings with the notches “b” in 
the upper crankcase.
 Be sure to install each crankshaft journal 
upper bearing in its original place.
2. Install:  Crankshaft
3. Install:  Lower crankcase Refer to CRANKCASE on page 5-55. 
						

							
TRANSMISSION
5-74
EAS26240
TRANSMISSION
Removing the transmission, shift drum assembly, and shift forks
Order Job/Parts to remove Q’ty RemarksLower crankcase 1 Refer to CRANKCASE on page 5-55.
1 Drive axle assembly 1
2 Circlip 1
3 Oil seal 1
4 Bearing 1
5 Shift drum retainer 1
6 Shift fork guide bar 2
7Spring 4
8 Shift fork-L 1
9 Shift fork-R 1
10 Shift drum assembly 1
11 Shift fork-C 1
12 Main axle assembly 1
13 Oil pipe 1
14 Oil baffle plate 1
15 Thrust plate 1
16 Washer 1 For installation, reverse the removal proce-
dure. 
						

							
TRANSMISSION
5-75
Disassembling the main axle assembly
Order Job/Parts to remove Q’ty Remarks1 Bearing 1
2 2nd pinion gear 1
3 Toothed lock washer 1
4 Toothed lock washer retainer 1
5 6th pinion gear 1
6 Collar 1
7 Washer 1
8 Circlip 1
9 3rd pinion gear 1
10 Circlip 1
11 Washer 1
12 5th pinion gear 1
13 Collar 1
14 Main axle 1
15 Bearing housing 1
16 Bearing 1 For installation, reverse the removal proce-
dure. 
						

							
TRANSMISSION
5-76
Disassembling the drive axle assembly
Order Job/Parts to remove Q’ty Remarks1 Washer 1
2 1st wheel gear 1
3 Collar 1
4 5th wheel gear 1
5 Circlip 1
6 Washer 1
7 Collar 1
8 3rd wheel gear 1
9 Toothed lock washer 1
10 Toothed lock washer retainer 1
11 4th wheel gear 1
12 Collar 1
13 Washer 1
14 Circlip 1
15 6th wheel gear 1
16 Circlip 1
17 Washer 1
18 2nd wheel gear 1
19 Collar 1
20 Collar 1
21 Oil seal 1
22 Bearing 1
23 Circlip 1
24 Drive axle 1 
						

							
TRANSMISSION
5-77
For installation, reverse the removal proce-
dure.
Disassembling the drive axle assembly
Order Job/Parts to remove Q’ty Remarks 
						

							
TRANSMISSION
5-78
EAS26250
REMOVING THE TRANSMISSION
1. Remove: Main axle assembly “1”
(with the Torx® wrench)
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a. Insert two bolts “2” of the proper size, as  shown in the illustration, into the main axle 
assembly bearing housing.
b. Tighten the bolts until they contact the  crankcase surface.
c. Continue tightening the bolts until the main 
axle assembly comes free from the upper 
crankcase.
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EAS26260
CHECKING THE SHIFT FORKS
The following procedure applies to all of the 
shift forks.
1. Check: Shift fork cam follower “1”
 Shift fork pawl “2” Bends/damage/scoring/wear  → Replace 
the shift fork. 2. Check:
 Shift fork guide bar Roll the shift fork guide bar on a flat sur-
face.
Bends  → Replace.
WARNING
EWA12840
Do not attempt to straighten a bent shift 
fork guide bar.
3. Check:
 Shift fork movement (along the shift fork guide bar)
Rough movement  → Replace the shift 
forks and shift fork guide bar as a set.
EAS26270
CHECKING THE SHIFT DRUM ASSEMBLY
1. Check:  Shift drum groove
Damage/scratches/wear  → Replace the 
shift drum assembly.
 Shift drum segment “1”
Damage/wear  → Replace the shift drum 
assembly.
 Shift drum bearing “2”
Damage/pitting  → Replace the shift drum 
assembly. 
						

							
TRANSMISSION
5-79
EAS26300
CHECKING THE TRANSMISSION
1. Measure: Main axle runout
(with a centering device and dial gauge “1”)
Out of specification  → Replace the main 
axle.
2. Measure:  Drive axle runout (with a centering device and dial gauge “1”)
Out of specification  → Replace the drive 
axle.
3. Check:  Transmission gears Blue discoloration/pitting/wear  → Replace 
the defective gear(s).  Transmission gear dogs
Cracks/damage/rounded edges  → Replace 
the defective gear(s).
4. Check:  Transmission gear engagement (each pinion gear to its respective wheel 
gear)
Incorrect  → Reassemble the transmission 
axle assemblies.
5. Check:
 Transmission gear movement Rough movement  → Replace the defective 
part(s).
6. Check: Circlips Bends/damage/looseness  → Replace.
EAS26350
INSTALLING THE TRANSMISSION
1. Install:
 Oil pipe “1”
 Main axle assembly “2” (with the Torx® wrench)
NOTE:
Make sure to caulk the bolts at three positions 
after installing the bearing housing.
2. Install: Shift fork-C “3”
 Shift drum assembly “4”
 Shift fork guide bar
NOTE:
 The embossed marks on the shift forks should face towards the right side of the 
engine and be in the following sequence: “R”, 
“C”, “L”.
 Carefully position the shift forks so that they 
are installed correctly into the transmission 
gears.
 Install shift fork-C into the groove in the 3rd 
and 4th pinion gear on the main axle.
Main axle runout limit
0.02 mm (0.0008 in)
Drive axle runout limit0.02 mm (0.0008 in)