Yamaha MZ300 User manual

MZ300
MZ360
SUPPLEMENTARY
SERVICE MANUAL
7CR-F8197-10LIT-19616-01-81
7CR-F8197-10_cover.indd 1 2012/03/06 10:26:00

7CR-F8197-10_cover.indd 2 2012/03/06 10:26:00

FOREWORD
This Supplementary Service Manual has been
prepared to introduce new service and new
data for the MZ300 and MZ360.
For complete information on service proce-
dures, it is necessary to use this Supplementary
Service Manual together with following manual:
This manual was written by the YAMAHA
MOTOR POWERED PRODUCTS CO., LTD.
primarily for use by Yamaha dealers and their
qualified mechanics. It is not possible to put an
entire mechanic’s education into one manual,
so it is assumed that persons using this book
to perform maintenance and repairs on
Yamaha Multi-Purpose Engine have a basic
understanding of the mechanical precepts and
procedures inherent to Multi-Purpose Engine
repair technology. Without such knowledge,
attempted repairs or service to this model may
render it unfit for use and/or unsafe.
YAMAHA MOTOR POWERED PRODUCTS
CO., LTD. is continually striving to further
improve all models manufactured by Yamaha.
Modifications and significant changes in speci-
fications or procedures will be forwarded to all
Authorized Yamaha dealers and will, where
applicable, appear in future editions of this
manual.
MZ300/MZ360
SUPPLEMENTARY SERVICE MANUAL
©2012 by Yamaha Motor
Corporation, U.S.A.
1st Edition, February 2012
All rights reserved. Any reprinting or
unauthorized use without the written
permission of Yamaha Motor
Corporation, U.S.A.
is expressly prohibited.
Printed in USA
LIT-19616-01-81
MZ300/MZ300R, MZ360/MZ360R
SERVICE MANUAL:
7RJ-28197-N0 (310069). April 1996
HOW TO USE THIS MANUAL
PARTICULARLY IMPORTANT
INFORMATION
Particularly important information is distin-
guished in this manual by the following
notations.
This is the safety alert symbol. It is used to
alert you to potential personal injury haz-
ards. Obey all safety messages that follow
this symbol to avoid possible injury or
death.
WARNING
A WARNING indicates a hazardous situa-
tion which, if not avoided, could result in
death or serious injury.
NOTICE
A NOTICE indicates special precautions
that must be taken to avoid damage to the
machine or other property.
TIP
A TIP provides key information to make
procedures easier or clearer.
MANUAL FORMAT
The procedures in this manual are organized
in a sequential, step-by-step format. The infor-
mation has been compiled to provide the
mechanic with an easy to read, handy refer-
ence that contains comprehensive explana-
tions of all disassembly, repair, assembly, and
inspection operations.
In this revised format, the condition of a faulty
component will precede an arrow symbol and
the course of action required will follow the
symbol, e.g.,
9 Bearings
Pitting/damage → Replace.
EXPLODED DIAGRAM
Each chapter provides exploded diagrams
before each disassembly section for ease in
identifying the correct disassembly and
assembly procedures.

ILLUSTRATED SYMBOLS
(Refer to the illustration)
SYMBOL DEFINITION SYMBOL DEFINITION
General information Wear limit, clearance
Periodic inspections and
adjustments Engine speed
Engine Electrical data
Electrical
M
Molybdenum disulfide oil
Specifications
E
Engine oil
Special tool LS Lithium-soap base grease
Filling fluid LT Apply locking agent (LOCTITE®).
Lubricant Replace the part with a new one.
T
R
.
.
Tightening torque MMolybdenum disulfide grease

INDEX
GENERAL INFORMATION GEN
INFO
PERIODIC INSPECTIONS
AND ADJUSTMENTS INSP
ADJ
SPECIFICATIONS SPEC
1
2
3

CHAPTER 1.
GENERAL INFORMATION
MACHINE IDENTIFICATION .....................1-1
SERIAL NUMBER ................................1-1
STARTING SERIAL NUMBER ..................1-1
DIMENSIONS .............................................1-2
DIMENSION CHART ............................1-2
MOUNTING BASE ................................1-2
TOP .......................................................1-3
SIDE ......................................................1-3
FRONT ..................................................1-4
SPECIAL TOOLS AND TESTERS .............1-5
CHAPTER 2.
PERIODIC INSPECTIONS AND
ADJUSTMENTS
INTRODUCTION ........................................2-1
PERIODIC MAINTENANCE/
LUBRICATION INTERVALS ......................2-1
CHAPTER 3.
SPECIFICATIONS
GENERAL SPECIFICATIONS ...................3-1
MAINTENANCE SPECIFICATIONS ..........3-2
ENGINE ................................................3-2
ELECTRICAL ........................................3-3

1-1
GEN
INFO
1
2
3
GENERAL INFORMATION
MACHINE IDENTIFICATION
SERIAL NUMBER
The serial number 1 is printed on the label 2
affixed to the position 3 of the Multi-Purpose
Engine as shown in the illustration.
TIP
The first four digits identifies a model, and
the remaining digits indicates a production
number.
STARTING SERIAL NUMBER
Model Code Serial number
AMZ300 A2 7CRJ 7CRJ-1000101
BMZ360 A2 7CTJ 7CTJ-1000101
TIP
Designs and specifications are subject to
change without notice.
7CR –
1
7CT –
1
A
B
MACHINE IDENTIFICATION/STARTING SERIAL NUMBER
1

1-2
GEN
INFO
DIMENSIONS
DIMENSION CHART
Unit: mm
Model (Code) PTO shaft dimensions (Type) Mounting face dimensions
MZ300 A2 (7CRJ)
25.4
146.08
21.8
110
72.2
28
60.3
88.5
6.31
5
4.5
0
-0.021
0
-0.1
0
-0.040
0
+0.054
0
+0.058
3/8-24UNF-2B
4 3/8-16UNC
4 M8 1.25
110
127
146.08
165.1
30
30
45
45
0
-0.040
0
+0.054
2B DEPTH 18
MZ360 A2 (7CTJ)
*1: UNF; Unified fine thread (Unit: in)
*2: UNC; Unified coarse thread (Unit: in)
MOUNTING BASE
(Unit: mm)
2 11
6537
16
2 11
90.5 105
DIMENSIONS

1-3
GEN
INFO
DIMENSIONS
TOP
(Unit: mm)
SIDE
(Unit: mm)
423
485
451
162
133.5
(195.5)
103
90.5
70
2 M8 1.25 DEPTH 18
284

1-4
GEN
INFO
DIMENSIONS
FRONT
(Unit: mm)
425
188
204
99
118
(37)
10262
(16)
65
2 11 (HOLE)
2 11 27 (SLOT HOLE)

GEN
INFO
1-5
SPECIAL TOOLS AND TESTERS
SPECIAL TOOLS AND TESTERS
The proper special tools are necessary for complete and accurate
tune-up and assembly. Using the correct special tool will help pre-
vent damage caused by the use of improper tools or improvised
techniques.
TIP
9 For U.S.A. and Canada, use part number starting with “YM-”,
“YU-”, or “ACC-”.
9 For others, use part number starting with “90890-”.
1. Narrow gauge set
P/N. YM-34483
Thickness gauge
P/N. 90890-03079
This gauge is used to adjust valve clearance, piston clearance
and piston ring end gap.
2. Cylinder gauge
Commercially obtainable
This instrument is used for checking cylinder bore size and
condition.
3. Digital tachometer
P/N. YU-39951-B, 90890-06760
This tool is needed for observing engine r/min.
4. Engine compression tester
P/N. YU-33223
Compression gauge
P/N. 90890-03081
This tool is used for checking engine compression.
5. Extension
P/N. YU-33223-3, 90890-04082
This tool is used for checking engine compression.
6. Dial indicator gauge
P/N. YU-03097
Dial gauge
P/N. 90890-03097
This instrument is used for checking crankshaft side clearance.
SVU1160
SVU1190

GEN
INFO
1-6
SPECIAL TOOLS AND TESTERS
7. Analog pocket tester
P/N. YU-03112-C
Pocket tester
P/N. 90890-03112
This instrument is necessary for checking the electrical system.
SVU1230
8. Oppama pet-4000 spark checker
P/N. YM-34487
Ignition checker
90890-06754
This instrument is necessary for checking the ignition system
components.
9. Primary clutch holder
P/N. YS-01880-A
Sheave holder
P/N. 90890-01701
This tool is necessary for holding the magneto rotor.
10. Six piece tappet set
P/N. YM-A5970
Tappet adjusting tool
P/N. 90890-01311
This tool is used to adjust the valve clearances.
ø9ø8 ø10
ø3 ø4
YM-A5970
90890-01311
3mm
11. Heavy duty puller
P/N. YU-33270-B
Flywheel puller
P/N. 90890-01362
This tool is necessary for removing the magneto rotor.
SVU1220
12. Valve spring compressor
P/N. YM-01253, 90890-01253
This tool is used to remove the valve springs.
13. Piston ring compressor
P/N. YM-08037, 90890-05158
This tool is used to compress the piston rings when installing
the piston.

2-1
INSP
ADJ
PERIODIC INSPECTIONS AND ADJUSTMENTS
INTRODUCTION
This chapter includes all information necessary to perform recommended inspections and adjust-
ments. These preventive maintenance procedures, if followed, will ensure more reliable machine
operation and a longer service life. The need for costly overhaul work will be greatly reduced. This
information applies to machines already in service as well as new machines that are being pre-
pared for sale. All service technicians should be familiar with this entire chapter.
PERIODIC MAINTENANCE/LUBRICATION INTERVALS
No. Item Remarks
Pre-Opera-
tion check
(daily)
Initial Every
1 month
or 20 hr
3 months
or 50 hr
6 months
or 100 hr
12 months
or 300 hr
1. Spark plug
Check condition,
adjust gap and clean.
Replace if necessary.
8
2. Valve
clearance
Check and adjust
when engine is cold. 8
3.
Crankcase
breather
system
Check breather hose
for cracks or damage.
Replace if necessary.
8
4. Idle speed Check and adjust
engine idle speed. 8
5. Exhaust
system
Check for leakage.
Retighten or replace
gasket if necessary.
8
Check spark arrester.
Clean/replace if
necessary.
8
6. Engine oil Check oil level. 8
Replace. 8 8
7. Air filter Clean. Replace if
necessary.
8
8. Fuel filter
Clean fuel petcock
and fuel tank filter.
Replace if necessary.
8
9. Fuel line
Check fuel hose for
cracks or damage.
Replace if necessary.
8
10. Choke lever Check choke
operation.
8
11. Cooling
system
Check for fan
damage.
8
12. Starting
system
Check recoil starter
operation. 8
13. Muffler screen Clean. Replace if
necessary.
8
14. Spark arrester
Check condition.
Clean and replace if
necessary.
8
2
INTRODUCTION/
PERIODIC MAINTENANCE/LUBRICATION INTERVALS

2-2
INSP
ADJ
INTRODUCTION/
PERIODIC MAINTENANCE/LUBRICATION INTERVALS
No. Item Remarks
Pre-Opera-
tion check
(daily)
Initial Every
1 month
or 20 hr
3 months
or 50 hr
6 months
or 100 hr
12 months
or 300 hr
15.
Decarbonization
More frequency if
necessary. 8
16. Fittings/
fasteners
Check all fittings and
fasteners. Correct if
necessary.
8

3-1
SPEC
GENERAL SPECIFICATIONS
SPECIFICATIONS
GENERAL SPECIFICATIONS
Model name MZ300 MZ360
Model code number 7CRJ 7CTJ
Dimensions:
Overall length mm (in) 425 (16.7)
Overall width mm (in) 451 (17.8)
Overall height mm (in) 485 (19.1)
Engine:
Type Air cooled 4-stroke gasoline OHV
Rated out put 6.8 (9.2) / 3600 7.6 (10.3) / 3600
kW (PS) / r/min
Starting method Recoil starter
Ignition timing BTDC 23° ± 3°
Fuel tank:
Fuel tank capacity 6.1 (1.61, 1.34)
L (US gal, Imp gal)
Engine oil:
Engine oil quantity 1.1 (1.16, 0.97)
L (US qt, Imp qt)
Recommended engine oil å YAMALUBE 4 (10W-40),
SAE 10W-30 or 10W-40
∫ SAE #30
ç SAE #20
∂ SAE 10W
Recommended engine oil
grade
API service SE type or higher
3

3-2
SPEC
Model name MZ300 MZ360
Model code number 7CRJ 7CTJ
Piston: mm (in)
Piston skirt “D”
77.960–77.980
(3.0693–3.0701)
84.977–84.998
(3.3456–3.3463)
<Limit> 77.904 (3.0671) 84.921 (3.3433)
Piston pin hole inside
diameter
20.004–20.015 (0.7874–0.7880)
Piston ring: mm (in)
Top ring
Dimensions “B × T” 1.50 × 3.40 (0.059 × 0.134) 1.50 × 3.60 (0.059 × 0.142)
End gap 0.20–0.35 (0.008–0.014)
<Limit> 0.9 (0.0354)
2nd ring
Dimensions “B × T” 1.50 × 3.40 (0.059 × 0.134) 1.50 × 3.60 (0.059 × 0.142)
End gap 0.30–0.45 (0.012–0.018) 0.20–0.35 (0.008–0.014)
<Limit> 0.9 (0.0354)
Oil ring
Dimensions “B × T” 2.50 × 2.80 (0.098 × 0.110) 3.0 × 3.0 (0.118 × 0.118)
Valve: mm (in)
Valve clearance (cold)
IN 0.07 (0.003)
EX 0.07 (0.003)
Valve spring: mm (in)
Set length
IN 29.0 (1.1417)
EX 29.0 (1.1417)
Set force
IN 10.0 kg (22.0 lb)
EX 10.0 kg (22.0 lb)
Tilt limit “A” 1.6 (0.06)
MAINTENANCE SPECIFICATIONS
ENGINE
MAINTENANCE SPECIFICATIONS
D
H
B
T
A

3-3
SPEC
Model name MZ300 MZ360
Model code number 7CRJ 7CTJ
Carburetor:
Type BV24-18 BV26-20
Bore size mm ø24 ø26
Main jet #100 #112.5
Pilot jet #53.8 #57.5
Pilot screw 1-1/2 1-3/4
Valve seat size mm ø1.8
Float height “H” mm (in) 14.9 (0.59)
MAINTENANCE SPECIFICATIONS
ELECTRICAL
Model name MZ300 MZ360
Model code number 7CRJ 7CTJ
Ignition system:
Spark plug cap resistance 3.75–6.25 kΩ
TCI:
Primary coil resistance 1.2 Ω
Secondary coil resistance 11.7 kΩ

3-4
SPEC

7CR-F8197-10_cover.indd 3 2012/03/06 10:26:00

PRINTED IN USA
(E)
7CR-F8197-10_cover.indd 4 2012/03/06 10:26:00