Echo PB-651T/H User manual

SERVICE MANUAL

PB-651T/H
PB-751
T/H
PB-755T/H
2
SERVICE INFORMATION
1 SERVICE INFORMATION
1-1 Specifications
Model PB-651T/H PB-751T/H PB-755T/H
Dimensions Length*
mm(in) 375 (14.8)
Width* mm(in) 485 (19.0)
Height* mm(in) 527 (20.8)
Dry weight** kg(lb)
11.2 (24.7) / 11.4 (25.1) 11.6 (25.7) / 11.8(26.1) 11.0 (24.2) / 11.2 (24.6)
Engine Type KIORITZ, air-cooled, two-stroke, single cylinder
Rotation Counterclockwise as viewed from the output end
Displacement cm3(in3) 63.3 (3.863)
Bore mm(in) 48.0 (1.89)
Stroke mm(in) 35.0 (1.38)
Compression ratio 6.3
Carburetor Type Rotary type: Diaphragm, horizontal-draught, with primer (purge bulb)
Model WalbroWYK-192
Ignition Type CDI (Capacitor discharge ignition) system
Spark plug BPM8Y
Exhaust Muffler type Spark arrestor muffler with catalyst
Starter Type Automatic rewind with shutter
Rope diameter x length mm(in) 3.5 x 1000 (9/64 x 39 1/2)
Fuel Type mm(in) Premixed two-stroke fuel
Mixture ratio 50 : 1 (2 %)
Gasoline Minimum 89 octane unleaded
Two-stroke air cooled engine oil ISO-L-EGD (ISO/CD13738), JASO FC
Tank capacity L (U.S.fl.oz.) 2.0 (67.64)
Throttle Mount T type Tube-mounted throttle with cruise contol
H type Hip-mounted throttle with cruise contol
Blower Fan type Centrifugal, single stage
Max. air volume (with pipes)
m3/min (ft3/min) 17.6 (620)**
Max. air velocity (with pipes)
m/s (mph) 92 (205)
Discharge ID mm (in) 62 (2.44)
ID : Inner diameter.
* Without blower pipes.
** With straight pipes.

PB-651T/H
PB-751
T/H
PB-755T/H
3
SERVICE INFORMATION
1-2 Technical data
Model PB-651T/H PB-751T/H PB-755T/H
Engine
Idling speed r/min 2400 - 2800
Wide open throttle speed r/min 6800 - 7300
Compression pressure MPa (kgf/cm2) (psi) 1.0 (10.2) (145)
Ignition system
Spark plug gap mm(in) 0.6 - 0.7 (0.024 - 0.028)
Minimum secondary voltage at 1000 r/ min kV 12
Secondarycoil resistance
k Ω
1.2 - 1.8
Pole shoe air gaps
mm(in)
0.3 - 0.4 (0.012 - 0.016)
Ignition timing
°BTDC
30
Carburetor
Venturi size mm(in) 15.0 (0.591)
Throttle bore
mm(in)
15.0 (0.591)
Idle adjust screw initial setting
turn in*
1 1/2
Test Pressure, minimum
MPa (kgf/cm
2
) (psi)
0.05 (0.5) (7.0)
Metering lever height
mm (in)
1.5 (0.06) lower than diaphragm seat
BTDC: Before top dead center.
* Set idle speed screw to the point that its tip just contacts throttle plate before initial setting.

PB-651T/H
PB-751
T/H
PB-755T/H
4
SERVICE INFORMATION
1-3 Torque limits
Descriptions
Size
kgf • cm
N• m
in• lbf
Starter Starter pawl assembly
M 10
80 - 100
8 - 10
70 - 90
system Starter case M 5*** 35 - 50 3.5 - 5 30 - 45
Ignition
Flywheel
M 10
200 - 240
20 - 24
175 - 210
system
C.D.I module
M 5
60 - 100
6 - 10
50 - 90
Fuel
Spark plug
M 14
150 - 170
15 - 17
130 - 150
system
Carburetor
M 5
40 - 55
4 - 5.5
35 - 48
Intake insulator
M 5
35 - 45
3.5 - 4.5
30 - 40
Fuel tank
M 5
20 - 40
2 - 4
17 - 35
Engine
Crankcase
M 5
70 - 110
7 - 11
60 - 95
Cylinder
M 5
70 - 110
7 - 11
60 - 95
Engine plate
M 5*
20 - 40
2 - 4
17 - 35
Engine mount
M 6
100 - 150
10 - 15
90 - 130
Cylinder cover
M 5
40 - 55
4 - 5.5
35 - 48
Engine cover
M 5**
20 - 40
2 - 4
17 - 35
Muffler
M 6***
110 - 150
11 - 15
95 - 130
Muffler stay
M 5
70 - 110
7 - 11
60 - 95
Muffler guide
M 4
15 - 25
1.5 - 2.5
13 - 22
Others
Fan
M 5
50 - 75
5 - 7.5
45 - 65
Fan case
M 5 **
40 - 55
4 - 5.5
35 - 48
Blower grid
M 5**
20 - 40
2 - 4
17 - 35
Cushion
Frame side
M 5***
20 - 40
2 - 4
17 - 35
Top M 5 ** 20 - 40 2 - 4 17 - 35
Bottoms
M 5** 80 - 100 8 - 10 70 - 90
Main pipe
M 5
20 - 40
2 - 4
17 - 35
High tension lead clip
M 5**
40 - 50
4 - 5
35 - 45
Harness fixture
M 5**
20 - 40
2 - 4
17 - 35
Trigger bracket fixture
M 5
20 - 30
2 - 3
17 - 26
Throttle lever
M 6
20 - 30
2 - 3
17 - 26
Regular bolt, nut and screw
M 3
6 - 10
0.6 - 1
5 - 9
M 4
15 - 25
1.5 - 2.5
13 - 22
M 5
25 - 45
2.5 - 4.5
22 - 40
M 6
45 - 75
4.5 - 7.5
40 - 65
M 8 110 - 150 11 - 15 95 - 130
Fan case side
* Tapping screw
** Tapping bolt
*** Apply thread locking sealant (See next page)

PB-651T/H
PB-751
T/H
PB-755T/H
5
SERVICE INFORMATION
1-4 Special repairing materials
Material
Location
Remarks
Grease
Rewind spring
Lithium based grease
Starter center post
Oil seal inner lips
Thread locking sealant
Ball bearing
Loctite #675 or equivalent
Muffler
Loctite #242, ThreeBond #1324 or equivalent
Starter case
Loctite #222, ThreeBond #1342 or equivalent
Cushion (Frame side)
Loctite #222, ThreeBond #1342 or equivalent

PB-651T/H
PB-751
T/H
PB-755T/H
6
SERVICE INFORMATION
1-5 Service limits
A B C D
5K247 5K248 5K249 5K250
E F G H
5K251 5K016 5K042 5K252
K L
5K219 5K220
Description
mm (in)
A
Cylinder bore
When plating is worn and aluminum can be seen
B
Piston outer diameter Min.
47. 95 (1.888)
C
Piston pin bore Max.
10. 03 (0.395)
D
Piston ring groove,
1st Max.
1. 65 (0.065)
2nd Max.
1. 6 (0.063)
E
Piston ring side clearance Max.
0. 1 (0.004)
F
Piston pin outer diameter Min.
9. 98 (0.393)
G
Piston ring width Min.
1. 45 (0.057)
H
Piston ring end gap Max.
0. 5 (0.02)
K
Con-rod small end bore Max.
14. 025(0.552)
L
Crankshaft runout Max.
0. 05 (0.002)