Zenoah G300PUM User manual

OWNER'S MANUAL
114 06 37-26 (1808)
Model: G300PUM for radio control Boat
WARNING
•This engine is designed for radio controlled boat use.
•When replacing parts, use only parts which have been
certified by Zenoah.
•Zenoah assumes that no responsibility for this engine
that is modified or used for any other applications.
•Purchaser has all responsibilities against any laws
and regulations existing in the country, Zenoah is
exempt from such laws and regulations.
•Read and completely understand this OWNER'S
MANUAL before operating this engine.

2
1. Safety Precautions ............................3
2. Engine Assembling............................4
3. Engine Mounting................................5
4. Screw Propeller .................................6
5. Fuel....................................................7
6. Starting ..............................................8
7. How to Stop The Engine....................8
8. Carburetor Adjustment ......................9
9. Engine Break-In.................................11
10. Operation...........................................11
11.
Maintenance......................................12
12. Special Tools.....................................17
13. Trouble Shooting ...............................18
14. Parts List............................................20
15. Warranty.............................................23
Contents
The engine exhaust from this
product contains chemicals
known to the State of California to
cause cancer, birth defects or
other reproductive harm.
WARNING AVERTISSEMENT ADVERTENCIA
Los gases de escape del motor de
este producto contienen
sustancias químicas conocidas
por el Estado de California como
causantes de cáncer,
malformaciones en recién nacidos
y otros problemas de
reproducción.
Les échappements du moteur de
ce produit contiennent des
produits chimiques connus par
l’Etat de Californie comme étant
responsables de cancers,
d’anomalies congénitales et
d’autres atteintes à l’appareil
reproducteur.
The engine exhaust from this
product contains chemicals
known to the State of California to
cause cancer, birth defects or
other reproductive harm.
WARNING AVERTISSEMENT ADVERTENCIA
Los gases de escape del motor de
este producto contienen
sustancias químicas conocidas
por el Estado de California como
causantes de cáncer,
malformaciones en recién nacidos
y otros problemas de
reproducción.
Les échappements du moteur de
ce produit contiennent des
produits chimiques connus par
l’Etat de Californie comme étant
responsables de cancers,
d’anomalies congénitales et
d’autres atteintes à l’appareil
reproducteur.

3
1. Safety Precautions
•This manual describes the engine. For its mounting and control, see the
instruction manual provided by model boat manufacturer.
•This engine is designed for model boat use. If it is used for any other
purpose, we cannot be responsible for its reliability, safety and any
laws/regulations in the country.
•Use genuine parts for replacement.
•Check the rotor and screw-propeller every time. If it is damaged, replace it
with a new one.
•If the screw-propeller hit something while the engine is in operation,
immediately stop the engine and check it.
•Start the engine on a flat surface without pebble stones.
•Never modify the rotor.
•Check the rotor. If it is damaged, replace it with a new one.
•When mixing the fuel, or operating the engine, carry it out in a well-
ventilated place.
•To prevent electrification, never touch the high-tension wire of the spark
plug during operation.
•The engine metal parts can burn your skin. Never touch the engine and
muffler during operation or right after stopping the engine.

4
The carburetor and air-funnel are not assembled at factory.
Make sure that the assembling for such parts are done according to the Fig.1.
Make sure that gasket and carburetor are mounted as described in fig.1.
The engine does not start if carburetor is mounted upside down position.
CAUTION
2. Engine Assembling
23
456
1
1. Engine
2. Gasket (T2075-13150)
3. Carburetor (580349001)
4. Air-funnel (848ES08300)
5. Spacer (1142-83110)
6. Screw (0263-30555)
Fig.1
G300PUM

5
3. Engine Mounting
Make sure that the engine is to be mounted according to the instruction manual
provided by model boat manufacturer.
In case such instruction manual is not available, make sure that the engine should
be mounted at least by 4 points both at engine's PTO side and recoil starter side.
[ Note ]
1) Be sure to set flat washers or metal plates on the reverse side of the
mount to prevent bolts from sinking into the mount.
Be sure to check if the bolts are securely fastened.
2) The fuel head between carburetor and the bottom of fuel tank must be less
than 100 mm (4 inches)

6
The exhaust system (e.g., muffler) is not equipped with this engine as standard.
When you select the exhaust system, check the engine speed (rpm) when the
maximum output is generated by using the exhaust system you are going to select.
And then decide the appropriate screw-propeller that would meet such engine
speed (rpm) that the exhaust system requires.
In general, standard size of the screw propeller (Surface prop type) are as follows:
Pitch ratio ( mm )
1.9 ~ 1.4
Diameter ( mm )
65 ~ 75
4. Screw-Propeller

7
•Mixed gasoline (octane over 90) and high grade 2 cycle engine oil (mixing use
type; JASO:FC grade or ISO: LEGC grade) at mixing ratio 25 : 1.
•The mixing ratio is according to the oil recommendation.
[ NOTE ]
1) Gasoline may contain maximum of 10% Ethanol (grain alcohol) or up to
15% MTBE (Methyl tertiary-butyl ether).
Gasoline containing Methanol (Wood Alcohol) is NOT approved.
2) Gasoline is very flammable. Avoid smoking, bringing any fires near fuel.
3) To prevent all possible problems on fueling system, make sure to use the
fuel filter which has more than 300 mesh or equivalent and gasoline proof
rubber pipe or equivalent.
Incorrect fuel filter use causes engine trouble like carburetor's fuel
passage stuffing or piston surface scratching etc.
5. Fuel

8
7. How to Stop The Engine
●How to start
a. Put fuel into the fuel tank.
b. While holding the equipment, pull out the starter rope swiftly.
c. In cold-starting, when the engine doesn't start. Partially choke the air-intake of
carburetor by finger to make engine fire.
6. Starting
For stopping the engine, the black lead wire from the coil should be grounded to
the engine body, or the throttle valve should be closed completely.
Red Lead
Black Lead
Kill Switch Engine Body Earth

9
8. Carburetor Adjustment
The carburetor is provided with 3 adjust screws they may need a little adjustment
depending on the temperature, atmospheric pressure (altitude), etc. of the area
where the engine is used. Start the engine without making any adjustments. Make
readjustments only when the engine shows any mal-running.
Standard opening of each needle as follows;
Low Speed needleHigh Speed needle
Idle Screw
HL
1 5/8±1/41 1/8±1/4

10
8. Carburetor Adjustment
Idle Screw:
Turning this screw clockwise increases the idling R.P.M. Turning it
counterclockwise decreases the idling R.P.M
Low Speed needle:
This is the fuel adjust screw (not the air screw). Turning this needle clockwise
makes the mixture gas leaner and turning it counterclockwise makes it richer.
Set this needle at a position which is 1/4 open from best mixture (maximum
R.P.M.) position.
High Speed needle:
Turning this needle clockwise makes the mixture gas leaner and turning it
counterclockwise richer. Set this needle at a position which is 1/8~1/4 open
(counter clockwise) from the maximum R.P.M. position.
1. Do not tighten the High and Low Speed needles too firmly.
2. When the unit has just started and the engine is not warm enough, there
may be insufficient acceleration and the engine may be stopped. Be sure
to perform idling before operation.
CAUTION

11
9. Engine Break-In
10. Operation
No specific break-in is required.
The engine is gradually broken-in as it is used and the output is also gradually
increased.
For checking the whole conditions of the boat, it may be better to operate the
engine at slow RPM for 1/3 tank and mid-high RPM for 2/3 tank.
•The engine is already tuned up to get high performance, and needs correct
maintenance to keep such high performance.
•The details of operating model boat shall be provided by model boat
manufacturer.
•Always keep the engine well according to the Maintenance clause described in
this owner's manual.

12
11. Maintenance
1) MAINTENANCE CHART
Before Every Every
Items Action Use 25 hours 100 hours Note
Leakage, Check ✔✔✔
Damage/Crack
Idling Speed Check/Adjust ✔✔✔
Spark Plug(gap) Check/Adjust ✔✔Replace if necessary
Cylinder(barrel) Check/Cleaning ✔✔ ↑
Piston, Ring Check/Cleaning ✔✔ ↑
Muffler & Bolt Check/Cleaning ✔✔✔ ↑
Bearings Check/Cleaning ✔✔ ↑
Crank Shaft Check/Alignment ✔↑
Rotor Check ✔✔ ↑
Water Jacket Check/Leakage ✔✔✔ ↑

13
11. Maintenance
2) Specifications & Technical Data
ITEMS SPECIFICATIONS
Engine model G300PUM
Type Water Cooled
Bore x stroke (mm) 36 x 29
Displacement (cm3)29.5
Effective Compression Ratio 8.6
Carburetor type Walbro WT-1048
Venturi (mm) ø13.5
Air funel —
Starting Recoil Starter
Ignition type CDI
BTDC (°/rpm) 30/7000
Sparkplug STD RZ7C
Option CMR6H/7H
Idle Speed (rpm) 3500
Weight (kg) 1.57
Specifications are subject to change without notice.

14
11. Maintenance
3) MAINTENANCE SPECIFICATIONS
G300PUM
Items Standard Limit Measuring Device Remarks
Bore (mm) ø36 Plating damaged Eye Checking
Diameter (mm) ø35.97 ø35.87 Micro Meter
Piston Ring 1.01 1.11 Thickness Gauge
Groove width (mm)
Piston Pin Hole (mm) ø8.01 ø8.05 Cylinder Gauge
Clearance between
Piston and 0.03~0.06 0.15
Cylinder (mm)
Clearance between
Groove and 0.02~0.04 0.1 Thickness Gauge
Piston Ring (mm)
End Gap (mm) 0.05~0.25 0.5 Thickness Gauge
Width (mm) 0.98 0.93 Micro Meter
Piston Pin Diameter (mm) ø8 ø7.98 Micro Meter
Connecting Rod Small end (mm) ø11 ø11.05 Cylinder Gauge
Crankshaft Dia. at Main Bearing (mm) ø12 ø11.98 Micro Meter
Eccentricity (mm) — 0.07 Dial Gauge
Axial Play (mm) — 0.5 Thickness Gauge
Gritty or
Main Bearing — —
Feels Flat Spot
A t the skirt end and the right
an
gle to the piston pin.
When inserted in a new cylinder.
Piston
Cylinder
Piston
Ring
Micro Meter
Cylinder Gauge

15
11. Maintenance
4) CARBURETOR
Items Unit Standard Measuring Device
Metering Lever set mm 1.65 ± 0.16 Vanier
MPa 0.16~0.26
Inlet Valve Opening Pressure Leak Tester
kg/cm21.6~2.6
MPa 0.08~0.18
Inlet Valve Closing Pressure Leak Tester
kg/cm20.8~1.8
5) IGNITION SYSTEM
Items Standard Limit Measuring Device Remarks
Spark Plug Air Gap (mm) 0.6~0.7 0.7 Thickness Gauge
Ignition Coil/Rotor Air Gap (mm) 0.3 0.4 Thickness Gauge
1160-71211 ∞/ 185Ω— Coil core – Red wire / Coil core – Black wire
2629-71210 ∞/ 255Ω— Coil core – Red wire / Coil core – Black wire
2.1kΩ—Sparkplug wire – Red wire
2629-71311 0.1 Ω—Volt Meter Red wire – Earth core
2.1 kΩ—Sparkplug wire – Earth core
Coil
Resistance
(Ω)
Source
Coil
Ignition
Coil
Volt Meter

16
11. Maintenance
6) TIGHTENING TORQUE
Standard Limit
Items Screw Size Remarks
N·m kg·cm N·m kg·cm
Carburetor M5 (P=0.8) 3.4 35 2.9~3.9 30~40
Insulator M5 (P=0.8) 4.4 45 3.9~4.9 40~50
Rotor M8 (P=1.0) 12.7 130 9.8~14.7 100~150
Cylinder M5 (P=0.8) 6.9 70 4.9~8.8 50~90
Crankcase M5 (P=0.8) 5.9 60 4.9~6.9 50~70
Spark Plug M10 (P=1.0) 10.8 110 8.8~12.8 90~130
Muffler M5 (P=0.8) 8.8 90 6.9~9.8 70~100
IG Coil M4 (P=0.7) 1.8 18 1.5~2.0 15~20
SO Coil M4 (P=0.7) 1.8 18 1.5~2.0 15~20
Recoil Starter M4 (P=0.7) 1.8 18 1.5~2.0 15~20
Water Jacket M3 (P=0.5) 1.5 15 1.0~2.0 10~20
Mount Plate M5 (P=0.8) 3.9 40 3.4~4.4 35~45

17
12. Special Tools
Part Name Part No. External Appearance Usage
1Puller Assy 577409701 To remove rotor.
2Piston Stopper 4810-96220
3Hex Wrench 3304-97611
4Snap Ring Pliers 5500-96110 To remove snap ring.
To hold crankshaft when
disassembling/assembling
the rotor.
For socket screw of
4mm, 5mm and 6mm.

18
13. Trouble Shooting
1) ENGINE DOES NOT START
Description Cause Countermeasure
No spark in the spark plug
Spark Plug 1. Wet spark, plug electrodes Make them dry
2. Carbon deposited on the electrodes Cleaning
3. Insulation failure by insulator damage Exchange
4. Improper spark gap Adjust to 0.6~0.7mm
5. Burn out of electrodes Exchange
Magneto 1. Ignition coil inside failure Exchange
2. Damaged cable sheath or disconnected cable Exchange or repair
Switch 1. Switch is OFF ON the switch
2. Switch failure Exchange
3.Primary wiring earthed Repair
Sparks appear in the spark plug
Compression & 1. Over sucking of fuel Drain excess fuel
fueling is normal 2. Too rich fuel Adjust carburetor
3. Overflow Carburetor adjust or exchange
4. Clogging of air cleaner Wash with mixed gasoline
5. Faulty fuel Change with proper fuel
Fueling normal but 1. Worn out cylinder, piston, or piston ring Exchange
poor compression 2. Gas leakage from cylinder and crank case gasket Apply liquid gasket and reassemble.
No fuel supply 1. Choked breather air hole Cleaning
2. Clogged carburetor Cleaning
3. Clogged fuel filter Exchange fuel filter

19
13. Trouble Shooting
2) LACK OF POWER OR UNSTABLE RUNNING
Description Cause Countermeasure
1. Air penetration from fuel pipe joints, etc Secure connection
2. Air penetration from intake tube joint or Change gasket or tightening screws
carburetor joint
3. Water in fuel Change with good fuel
4. Piston start to seizure Replace piston(and cylinder)
5. Muffler choked with carbon Cleaning
Overheating 1. Fuel too lean Adjust carburetor
2. Clogging of cylinder fin with dust Cleaning
3. Poor fuel quality Exchange with proper fuel
4. Carbon deposited in the combustion chamber Cleaning
5. Spark plug electrode red hot Thoroughly clean, adjust spark gap
[ 0.6~0.7(0.023~0.028in) ]
Others 1. Dirty air cleaner Wash with mixed gasoline
2. Over loading Reduce load

20
14. Parts List