Zenoah G620PU User manual

OWNER’S MANUAL
848H5693A3 (208)
August 2012
•Do not modify any parts of the engine.
•This engine is designed to be used to Radio
controlled products.
•In case any modification by customer,
ZENOAH shall not bear any responsibility from
the damage caused by such modification.
•Keep ignition system well maintained.
WARNING
●この製品はラジオコントロール
飛行機用に設計されています。
●改造、組み替えされて使用され
た場合当社は一切の責任を負い
ません。
●特に電装品は常に点検、整備し
てご使用ください。
警 告
MODEL: G620PU
G620PU-1

•This manual describes the engine. For its mounting and control, see the instruction
manual for a model plane.
•This engine is designed for use on the model plane. If it is used for any other
purpose, we cannot be responsible for its reliability or safety.
•Use genuine parts for replacement.
•Check the propeller every time. If it is damaged replace it with a new one.
•If the propeller hits something while the engine is in operation, immediately stop
the engine and check it.
•Start the engine on flat surface without pebble stones.
•Never modify the flywheel.
•Check the flywheel. 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.
Make sure that the engine is mounted on the aircraft grade plywood with more than 10mm of
thickness or a mount of equivalent strength and is firmly fixed with 4 bolts.
[ NOTE ]
1. Be sure to set flat washers or metal plate on the reverse side of the mount to prevent
bolts from sinking into the mount. Before flying the air-plane, be sure to check for loose
bolts.
2. The mounting bolts should be screwed into the crankcase within 8 ~ 12 mm of depth.
3. Since this engine is equipped with a float-less carburetor with a diaphragm pump, the
direction of cylinder and position of fuel tank can be freely selected.
1. Recommended prop size.
The recommended prop sizes are as shown in the table bellow.
This engine produces the maximum output when the engine is running at about
8,500rpm. Be sure to use a propeller which makes the engine speed approximately
7,000 ~ 9,000rpm while the airplane is flying. When using a propeller of small diameter, a
light weight propeller is not suitable.
2. There are two types of propeller mounting bolts; L=45 and L=50. Select the proper type
of bolt depending on the thickness of propeller used and the use of the spinner.
[ NOTE ]
1. When mounting a thin propeller, cut off the end of bolt or add a flat washer.
2. When mounting the spinner, set a pin on the hub with more than 3 mm of diameter, thus
preventing slipping.
•Mix gasoline (octane over 90) and high grade 2 cycle engine oil (mixing use type; F3C
grade or ISO-L-EGC grade) at mixing ratio 25~40:1.
•The mixing ratio is according to the oil recommendation.
4. Fuel
3. Propeller
2. Mounting
1. Safety Precautions
2
Diameter x Pitch (in.)
22 x 6 ~ 8, 20 x 7 ~ 10, 18 x 8 ~ 12

[ 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.
Hand flip start
Since the engine is equipped with the ultra compact C.D.I. type flywheel magneto ignition
system, it should be started according to the following procedure;
✽The magneto system of the engine is designed in such a way that when the exhaust port
is closed by the piston, that is, when the compression stroke starts (Refer to Fig.1-A),
sparks are never produced on spark plug no matter how fast the propeller may be flipped.
Be sure to quickly flip the propeller when the edge of magnet on the rotor is approaching
the coil (Fig.1-B). It means that the propeller should be quickly flipped about 90 degrees
in crank angle before the compression is about to start.
✽Because of the above conditions the propeller should be mounted to the hub as shown in
(Fig. 2) and quickly flipped within the range of about 180˚ from the horizontal position.
[ NOTE ]
When the engine is mounted so the cylinder is kept horizontal, the propeller should be set at
a different angle of 90˚.
How to Start the Engine
1. Fill the fuel tank with the fuel.
2. Close the choke valve and open the throttle valve approximately 1/3 ~ 1/2 of the full open
position.
3. Quickly flip the propeller in the counterclockwise direction according to the procedure
described above. When flipped several times, the sound (popping sound) of initial
explosion is heard.
4. When the initial explosion is heard, open the choke valve, set the throttle valve at the idle
position or at the position slightly open from the idle position and flip the propeller a few
more times. Then, the engine starts.
5. Operation
3
Magnet
Coil
A
Fig.1
B
Cut portion
Fig.2
The cut portions of propeller
mount and the propeller should
be set in the same direction.

4
[ NOTE ]
•Be sure to open the choke when the initial explosion is heard.
•When the choke is opened, be sure to close the throttle valve to a position near the idle
position before starting the next flipping (If the engine is started while the throttle is wide
open, a great thrusting force is produced, which is very dangerous).
•Be sure to wear a thick glove when flipping the propeller. Use all fingers, except thumb,
for the flipping operation.
How to Stop the Engine
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.
The carburetor is provided with 3 adjust screws which are set to the best (approximately)
positions by our company, but 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-functioning.
[ NOTE ]
Be sure to stop the engine before starting the adjustment, thus ensuring safety.
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.
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 1/4
open from the maximum R.P.M. position while the airplane is on ground.
[ NOTE ]
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.
No specific break-in is required. The engine is gradually getting break-in as it is used and the
output is also increased gradually.
This engine is used for power source for radio controlled airplane so you are strictly
requested to check engine and relative parts of airplane.
8. Maintenance
7. Engine Break-in
6. Carburetor Adjustment
KILL
SWITCH
BLACK
LEAD
RED LEAD
ENGINE BODY EARTH
Low Speed
Needle High Speed
Needle
Idle Screw
Standard Opening Position :
LOW SPEED NEEDLE : 11/2±1/4
HIGH SPEED NEEDLE : 11/4±1/4

5
1) Daily check (before starting)
•Leakage, damage, crack
•Muffler fixing bolts (torque, crack)
•Propeller hub (transformation, fixing bolts/nut)
(P/N: 2629-51410 or 2629-91510, 3544-11510 and 1100-43231)
•Rotor (transformation, play, airgap)
2) Every 25 hours check
•Spark plug (gap, cleaning)
•Cylinder (abrasion)
•Piston/Ring (abrasion)
•Bearing (Gritty)
According to the checks, replace any part if necessary.
The engine can be disassembled or reassembled without any specific difficulties, but be
careful of the following matters;
a. For disassembling, the special tools shown in the parts list are required in addition to the
general tools. Be sure to use a new gasket when the crankcase and cylinder have been
disassembled.
b. Removing rotor
1. Screw in the stopper (P/N:3350-96220) in place of the spark plug. Then turn the rotor
counterclockwise until the piston touches the stopper. Take care it can cause damage
to the piston or connecting rod if the stopper is not screwed in to the bottom.
2. Loosen and remove the rotor securing nut.
3. Remove the rotor by using the puller (P/N:1490-96101). Do not hit on the crankshaft by
a hammer, that can increase the runout of the shaft.
c. Assembling crankcase
1. Apply grease on the oil seal lips and oil on the bearing.
2. Assemble the crankshaft with a new gasket.
3. When both front and rear crankcases are tightened, the portion of gasket protruding on
the cylinder mounted surface should be cut off with a knife until the gasket becomes
flush with the cylinder mounted surface.
d. Assembling piston
Before assembling the piston, apply the oil on the small end bearing and piston, and set
the piston ensuring that the arrow mark on the top of piston is directed toward the
direction of exhaust port.
e. Assembling cylinder
1. Coat the oil on the inner surface of cylinder.
2. The piston is provided with a knock pin which stops the piston ring from turning. Set the
splitted section of piston ring at the knock pin and assemble the cylinder ensuring not to
break the piston ring.
f. Assembling rotor
Make sure to put lock tight (Medium strength type: TreeBond 1322N, LOCTITE 242,243,
PACER ZAP Z-42) on the rotor fixing nut (P/N:1100-43231).
g. Adjusting air gap of coil.
The air gap of coil should be adjusted to 0.3 mm (0.01").
h. Adjusting ignition time.
This engine with the point-less C.D.I. type requires no adjustments of ignition time.
9. Servicing

6
10. Specifications
11. Parts List
Model ......................................................G620PU · G620PU-1
Type .........................................................Air cooled two stroke cycle gasoline engine
Displacement ...........................................62.0cc (3.78cu. in)
Bore x Stroke ...........................................47.5mm x 35mm (1.87 in x 1.38 in)
Compression ratio ...................................8.2 : 1
Maximum Output .....................................5.7 PS/9500rpm [4.9 PS/9500rpm with Muffler]
Operating engine speed ..........................2000 ~ 10000rpm
Weight .....................................................2.0kg (4.4Ibs) [2.3kg (5.1Ibs) with muffler]
Ignition system .........................................CDI type Flywheel magneto
Carburetor ...............................................WALBRO HDA-48D
Fuel ..........................................................Gasoline oil mixture 25 ~ 40 : 1
Spark plug ...............................................CHAMPION RCJ-7Y
Recommended prop sizes (inch) .............22 x 6 ~ 8, 20 x 7 ~ 10, 18 x 8 ~ 12
Specifications are subject to change without notice.
G620PU, G620PU-1

7
13366-12116 Cylinder 1
2848C9014B3 Gasket,insulator 1
32618-14120 Insulator 1
4848C9014C2 Gasket,carburetor 1
52616-14211 Gasket,cylinder base 1
63310-12281 Bolt 4
72629-15111 Muffler 1
83356-15210 Gasket,muffler 1
9T2100-15220 Bolt 2
10 2850-15230 Nut 2
11,12 2629-21100 Crankcase comp. 1
13 2629-21130 • Pin 3
14 04065-03515 Snap ring 1
15 06030-06202 Bearing 2
16 1520-21220 Oil seal 1
17 1400-21220 Oil seal 1
18 2629-21311 Gasket,crankcase 1
19 3350-21320 Bolt 4
20 2618-41112 Piston 1
21 2618-41210 Ring,piston 2
22 3366-41310 Pin,piston 1
23 3350-41320 Snap ring 2
24 1400-41410 Needle bearing 1
25 2616-41510 Thrust washer 2
26 2629-42002 Crankshaft comp. 1
27 1000-43240 Key 1
28 1300-42410 Shim 0~2
29 1100-43231 Nut 1
30-1 2628-51101
Hub,propeller comp. for G620PU-1 1
30-2 04025-00312 • Pin for G620PU-1 2
31 2629-51111
Hub,propeller comp. for G620PU 1
32 3544-11510 Bolt 2
33 2629-51310 Washer,hub 1
34 2629-51410 Bolt, L45 1
35 1490-71110 Rotor 1
36 2629-71210 Source coil 1
37 2629-71311 Ignition coil 1
38 2850-72110 Cap,plug 1
39 1400-72121 Spring,plug cap 1
40 0263-30416 Screw 2
41 0260-30422 Screw 2
42 3699-90032 Spark plug, RCJ-7Y 1
43 2629-81004 Carburetor assy, HDA-48D 1
44 • Body assembly 1
45 3306-81380 • Screen, inlet 1
46 3350-81130 • Cover, pump 1
47 3350-81140 • Cover, diaphragm 1
48 2629-81150 • Shaft assy, throttle 1
Q' ty
/unit
DescriptionParts No.
Index
No.
49 3366-81340 • Valve, throttle 1
50 3356-81170 • Shaft assy, choke 1
51 2629-81180 • Valve, choke 1
52 3350-81190 • Stop, throttle 1
53 3356-81310 • Valve, inlet 1
54 3350-81220 • Ball, friction 1
55 3350-81230 • Gasket, pump 1
56 3350-81240 • Gasket, diaphragm 1
57 3350-81250 • Lever, metering 1
58 2618-81260 • Diaphragm, pump 1
59 3350-81270 • Diaphragm assy 1
60 2880-81470 • Screw, valve 3
61 3310-81240 • Screw, metering lever 1
62 1491-81130 • Screw, pump cover 1
63 3310-81250 • Pin, metering lever 1
64 2630-81330 • Screw, idle speed 1
65 3310-81351 • Screw assy 4
66 3350-81350 • Spring, friction 1
67 1491-81160 • Spring, needle adjust 2
68 3350-81370 • Spring, metering lever 1
69 3350-81380 • Spring, idle speed 1
70 2629-81390 • Spring, throttle return 1
71 2629-81411 • needle, high speed 1
72 2629-81420 • needle, idle 1
73 1480-81420 • plug, welch 1
74 2629-82210 Bolt 2
75 01641-20508 Washer 2
76 01601-20513 Washer 2
77 2629-91510 Bolt, L50 1
78 01641-21016 Washer 1
79 0290-21025 Washer 1
80 2628-91110 Mount 1
81 01252-30614 Bolt 4
82 0290-20615 Washer 4
83 1490-96101 Puller assy (Optional) 1
84 3350-96220 Stopper (Optional) 1
85 3356-96230 Guide, piston pin (Optional) 1
Q' ty
/unit
DescriptionParts No.
Index
No.
✽
for G620PU-1

G620PU, G620PU-1

12. Warranty
Printed in Japan
Head Office : 1-9 Minamidai, Kawagoe-city, Saitama, 350-1165 Japan
Phone: [phone] Fax: [phone]
WARRANTY TERMS
1) Scope of Application
This engine manufactured by Husqvarna Zenoah Co., Ltd. (herein after “Zenoah”).
And sold to the user directly or through distributor/manufacturer, shall entitle to be
covered by this warranty.
2) Limits of Warranty
Zenoah warrants that;
1. The quality disclosed in the specifications.
2. The engine which shall be considered defective by Zenoah, caused by material or
production fault.
3) Limits of Compensation
1. Zenoah compensates such quality, material and production faults by repairing or
replacing through distributor/manufacture.
2. Zenoah shall not compensate any other accompanied or benefit losses caused to
user and distributor/manufacture by such faults and through repairing or
replacing.
4) Term of Warranty
Three (3) months after purchased by end- user subject to 12 months from produced
month.
5) Exempt from Warranty
Zenoah shall not warrant this engine even if the fault has been caused during the
period of terms of Warranty, in case that.
1. Any faults, failures caused from neglect of proper operation and maintenance
described in OWNER’S MANUAL.
2. Any modification not approved by Zenoah.
3. Normal abrasion and deterioration.
4. Consuming parts.
5. Using any parts which have not been certified by Zenoah.
6. Add-on or modified use.