LONCIN G250F User manual

SERVICE MANUAL
（ ）
（ ）

Preface
PREFACE
This manual covers construction, function and
servicing procedures of the G250F(D)S
snow engine. Careful observance of the
instruction given herein will result in better, safer
service work.
Due to product improving, we can change
specification ；
CONTENTS
Safety and General Information
1
Specification
2
Maintenance
3
Disassembly and service
4
ALL INFORMATION, ILLUSTRATIONS,
DIRECTIONS AND SPECIFICATION INCLUDED
IN THIS PUBLICATION ARE BASED ON THE
LATEST PRODUCT INFORMATION AVAILABLE
AT THE TIME OF APPROVAL FOR PRINTING.
LONCIN GENERAL-PURPOSE ENGINE CO.,
LTD RESERVES THE RIGHT TO MAKE
CHANGES AT ANY TIME WITHOUT IN
CURRING ANY OBLIGATION WHATEVER.
NO PART OF THIS PUBLICATION MAY
BE REPRODUCED WITHLOUT
WRITTEN PERMISSION.

Section 1 Safety and General Information
1、Safety and General Information
1.1 General safety --------------------------------------------------1－2
1.2 Service rules ----------------------------------------------------1－3
1.3 Serial number location----------------------------------------1－4
1.4 Oil Recommendations ----------------------------------------1－5
1.5 Torque values AND Other Detail Specs ------------------1－5
1.6 Maintenance standards---------------------------------------1－7
1.7 Troubleshooting ------------------------------------------------1－8
1.8 Special tool ------------------------------------------------------1－11
1
1-1

Section 1 Safety and General Information
Safety Precautions
To ensure safe operation please read the following statements and understand
their meaning. Also refer to your equipment manufacturer's manual for other important
safety information. This manual contains safety precautions which are explained below.
Please read carefully.
1.1 General safety
WARNING
NOTE
Note is used to notify people of installation, operation, or maintenance information that is
important but not hazard-related.
Pay attention to these symbols and their meaning
：
WARNING: Warning is used to indicate the presence of a hazard that can cause severe
personal injury, death or substantial property damage if the warning is
ignored.
CAUTION: Caution is used to indicate the presence of a hazard that will or can cause
minor personal injury or property damage if the caution is ignored.
·Stop the engine before servicing, first stop the engine, and remove the spark plug.
·
When the engine is running, make sure the area is well ventilated. Never run the engine in an enclosed
area. The exhaust contains poisonous carbon monoxide gas.
·
Don’t smoke or fire on operation site due to gasoline extremely flammable and explosive under certain
conditions.
·Don’t close to revolved or overheat parts or high voltage lead when running.
·Don’t maintain until the engine is cooled. Otherwise, burn can happen in the hot state of engine.
Section 1
Safety and General Information
1-2

Section 1 Safety and General Information
1.2 Service rules
Follow the instructions represented by these symbols when maintaining：
：Used oil ：Used special tool ：Used grease
○×○(○)：Indicates flange bolt model, length and quantity.
P. ：Indicates pages
1. Use genuine LONCIN or LONCIN-
recommended parts and lubrication oil.
Parts that don’t meet design specifications
may damage the device or engine.
2. Use the special tools designed for this unit.
3. Install new paper gaskets, O-ring when
reassembling.
4. When screwing bolts or nuts, begin with
larger-diameter inner bolt first, and
tighten to the specified torque diagonally
unless a particular sequence is specified.
5. Clean parts in cleaning solvent upon
disassembly. Lubricate any sliding
surfaces before reassembly.
6. After reassembly, check all parts for proper
installation and operation.
1-3

Section 1 Safety and General Information
1.3 Serial number location
The serial number on stamped on the crankcase, as shown on the following drawing when inquiring
about engine or ordering parts in order to get correct parts for the unit being serviced by LONCIN
INDUSTRIAL CO., Ltd’s dealer
TXXXXX XX XX XXXXXXX
ENGINE TYPE
SERIAL NUMBER
1-4
Serial no.
Production month
Production year
Development order no.

Section 1 Safety and General Information
1.4 Oil Recommendations
When the ambient temperature is under -25℃～-30℃, SAE 0W-30/40 is recommended for general
use; when the ambient temperature is above -25℃but under 4.4℃, SAE 5W-30 or 0W30/40 is
recommended for general use. The SA oil viscosity and service classification are in theAPI label on the
oil container. We recommend that you use API SERVICE Category SF or higher class oil.
The SA oil viscosity and service classification are in the API label on the oil container. We
recommend that you use API SERVICE Category SE or SF oil.
1.5 Torque values AND Other Detail Specs
Note: For ALL bolts and nuts listed above, refer to the table of standard torque values.
Bolts and Nuts
Bolts or Nuts
Specs
Torque (N.m)
Dosage
Cylinder Head Cover Bolts
M6×16
8～12
4
Cylinder Head Bolt
M10×65
32～35
4
Shroud Bolt
M6×8
8～12
2
Bottom Shroud Bolts
M6×8
8～12
2
Oil drain extension rod
M12
26～30
1
Connecting Rod Bolts
M7×32
13～15
2
Crankcase Cover Bolts
M8×32
27～30
6
Flywheel Nut
M14×1.5
80～90
1
1-5

Section 1 Safety and General Information
Breather Chamber Bolt
M5×10
8～12
2
Ignition Coil Bolts
M6×25
8～12
2
Starter Bolt
M6×12
8～12
3
Recoil Start Bolts
M6×8
8～12
4
Control Assy Bolt
M6×8
8～12
2
Starter Motor Bolt
M6×35
8～12
2
Governor Arm Nut
M6
8～12
1
Air cleaner Nuts
M6
8～12
2
Protector Muffler Bolts
M6×12
8～12
6
Muffler Hex Nuts
M8
27～30
2
Fuel Tank Bolt
M6×12
8～12
1
Holder Electric Starting Box Bolt
M6×20
8～12
1
Engine Cover2 Bolts
M6×20
8～12
3
Engine Cover1 Acorn Nut
M6
8～12
2
Start Motor Cross Screw
M4×55
1.5～3
2
EX.Stud
M8×34
27～30
2
IN.Stud
M6×113
8～12
2
Valve Adjusting Bolts
M8
26～32
2
Valve Adjusting Nuts
M6
8～12
2
Spark Plug
F7RTC
27～30
1
Note: For ALL Other Detail Specs
Other Detail Specs
Item
Specs
Torque (N.m)
Bolts or Nuts
M4
1.5～3
M5
4～7
M6
8～12
M8
20～28
M10
35～40
M12
50～60
1-6

Section 1 Safety and General Information
1.6 Maintenance standards
Unspecified unit : mm
Part
Item
Standard
Service Limit
G250F(D)S
Engine
Maximum speed（rpm/min）
3300±100
cylinder
Sleeve(inside diameter)
75
75.17
piston
skirt outside diameter
74.97
74.82
Clearance to cylinder
0.015-0.05
0.12
Piston pin bore inside diameter
18.002
18.048
piston –pin clearance
0.002-0.014
0.06
piston pin
Outside diameter
18
17.954
piston ring
side gap
0.015-0.045
0.15
close gap
(top ring)
0.2-0.4
1.0
close gap
(the second ring)
0.3-0.5
1.0
close gap
(oil ring)
0.2-0.7
1.0
Width (top ring)
1.0
0.87
Width ( second ring)
1.2
1.07
connecting rod
small end inside diameter
18.006~18.017
18.07
big end inside diameter
30. 22~30.233
30.274
big end side clearance
0.25-0.65
1.1
crankshaft
neck diameter
29.975-29.99
29.915
valve
Clearance(cold) (intake)
0.10-0.15
－
Clearance(cold) (exhaust)
0. 15-0.20
－
Stem diameter (intake)
5.468~5.48
5.318
Stem diameter (exhaust)
5.428~5.44
5.275
Valve guide
Inside diameter (intake, exhaust)
5.50~5.512
5.572
Stem to guide clearance (intake)
0.02-0.044
0.10
Stem to guide clearance exhaust)
0.06-0.084
0.12
Valve seat
Seat width
0.8
2.0
Valve spring
free length
34~35
32.5
Cam shaft
height (intake)
28.52
28.27
height (exhaust)
28.56
28.31
Outside diameter (bearing)
13.966~13.984
13.916
crankcase cover
Camshaft hole diameter
14.0~14.018
14.048
spark plug
gap
0.7-0.8
－
igniter coils
resistance (primary)
1.0-1.2Ω
－
resistance (secondary)
5.1-6.1Ω
－
gap to flywheel
0.35-0.45
－
1-7

Section 1 Safety and General Information
Oil is sticky at
low temperature
Oil is good
1.7 Troubleshooting
a. Possible cause
b. Starting trouble at low temperature
1. First, check fuel level
2. Check oil
3. Reassemble spark plug and
check electrode
4. Put the spark plug on the cap,
connect electrode to grounding
then, pull the starter and check
igniting.
Add fuel and restart
No fuel
Have fuel
Change the correct oil make
Dry
Wet
Check fuel tube or filter clogged
Check carburetor, nozzle tube
clogged.
Wash electrode, and check
throttle open.
If overflowing, check float valve
No or weak
spark
Replace new spark plug, recheck the
igniting state. Check high voltage lead if
switching off or broken or creepaging.
Check igniter coils.
Good spark
Starting trouble
at low
temperature
Incorrect oil make
Primer pump or primer pump hose damage
Igniter coil trouble
Wrong igniter coil gap
Carburetor trouble
Spark plug trouble
Governor adjusting improper
Wrong valve gap
Valve or valve retainer damaged
Cylinder, piston or piston ring damaged
High speed abnormal
Insufficient
power
Unstable RPM and pre-fire
1-8

Section 1 Safety and General Information
※Check cylinder pressure
1) Disassemble spark plug cap and spark plug.
2) Assemble pressure meter in the spark plug hole.
3) Pull recoil starter several times to measure
cylinder pressure
c. Starting poor
Cylinder
pressure
At 600rpm,
6.0-8.5 Kgf/cm2
5. Inspecting cylinder pressure:
Put the pressure meter on the
spark plug hole and pull starter,
check pressure.
6. Assemble spark plug correct,
restart engine to test.
Pressure
insufficient.
Check valve gap if correct.
Check cylinder cover if
tightened.
Check combustion chamber if
damaged.
Check pad, valve or valve
retainer
Check piston ring, piston and
Check spark
igniting state.
Spark plug
gap
0.7-0.8mm
Replacing spark plug
Switch off
the black
lead, and
recheck.
Engine switch
trouble
Replacing
Poor insulating
High voltage
broken and
creepaging
No
spark
Affirm resistance
of the first and
second class of
igniting coils
Igniting coil
trouble
Replacing
igniting coils
Starting
poor
Check
by new
spark
plug
No
spark
Good
spark
Having
Wrong
resistance
value
7. Pressing the primer pump in
awrong way
Press the pump with thumb
quickly less than 3 times
1-9
Pressure meter

Section 1 Safety and General Information
Checking spark
1) Remove spark plug
2) Put the spark plug on the spark cap
3) Connect (－) electrode of the spark plug（thread）to grounding, pull starter to check if there is spark
at the electrode joint.
WARNING
d. Overheating
e. Engine performance poor
Don’t grab spark terminal by wet hand
when testing.
If touching the high voltage line by wet
hand, pulling starter can produce high
voltage electric, being danger.
Sprinkled fuel can cause fire around the
spark plug. First, clean the fuel, then
check. When checking, keep far away from
the spark plug hole.
Engine starts, but stops
immediately
Spark plug dirt and wet
Carburetor fuel level too high
Carburetor bolt adjusting wrong
Carburetor insulator damaged
Engine speed does not increase
Spark plug trouble/dirt
Throttle closed
Clogged muffler
Improper valve timing
Water in the carburetor
Overheating
Poor valve seat contact
Over load
Engine speed does not decrease
Governor out of adjustment
Throttle out of seat
Faulty governor slider
Speed does not stabilize.
Governor out of adjustment
Clogged carburetor idle speed nozzle
Carburetor tightening screw out of adjustment
Bad oil in the carburetor
Carburetor insulator damaged
Unhooked governor spring
Fuel level low or no
Engine overheating
Cylinder pad or head cover sealing
pad trouble
Oil level low
spark plug
1-10

Section 1 Safety and General Information
1.8 Special tool
Ser.
No.
Description
Note
1
Driver lever，40 mm
6、7、8 lever
2
42×47 mm outside retainer
6204 bearing assembly
52×55 mm outside retainer driver
6205、62/22 bearing assembly
3
30 mm inside retainer driver
timing gear
35 mm inside retainer driver
governor driving gear assembly
4
22 mm assistant driver
62/22 bearing assembly
20 mm assistant driver
6204 bearing assembly
25 mm assistant driver
6205 bearing assembly
30 mm assistant driver
6206 bearing assembly
5
Diamond grinder 45°φ24.5
grinding exhaust valve seat face
Diamond grinder 45°φ27.5
grinding intake valve seat face
Diamond grinder 32°φ25
rinding exhaust valve seat face
Diamond grinder 32°φ28
grinding intake, valve seat face
Diamond grinder 60°φ30
grinding intake, exhaust valve seat face
6
Grinder lever
Grinding valve seat face
7
Flywheel dismounter
Dismounting flywheel
8
Driver lever
2、3、4 lever
9
Valve guide dismounter
Dismounting and assembling guide
10
Valve guide reamer
Guide precision reaming
11
Float height gauge
Carburetor oil height
12
Digit multimeter
Electric testing
1-11

Section 2 Specifications
2、Specifications
2.1 Parameter ---------------------------------------------------------2－2
2.2 Dimensional drawings ------------------------------------------2－4
2.3 P.T.O Dimensional drawings ----------------------------------2－5
2
2-1

Section 2 Specifications
2.1 Parameter
LONCIN SNOW ENGINE SPECIFICATION
MODEL
G250F(D)S
ENGINE TYPE
SINGLE CYLINDER, 4-STROKE, FORCED AIR COOLING, OHV25°
DISPLACEMENT(cc)
252
Bore×Stroke(mm)
75×57
COMPRESSION RATIO
8.5：1
MAX.POWER（KW)
5.2
MAX.TORQUE（N.m/rpm)
15.6/2600
No LOAD SPEED（rpm）
3300±100
OIL CAPACITY( L)
0.7
FUEL CAPACITY (L)
3.0
FUEL CONSUMPTION (g/Kw.h)
≤375
IDLE SPEED (rpm)
no
SPEED FLUCTUATING RATIO
≤10%
NOISE (≤)
70db(A)
ROTATION
ANTI-CLOCKWISE (from P.T.O. side)
FUEL TYPE
REG.UNLEADED
IGNITION MODE
TRANSISTORIZED MAGNETO IGNITION
LUBRICATION SYSTEM
SPLASH
STARTING SYSTEM
RECOIL/ELECTRIC START
DRY WEIGHT(Kg)
21
SNOW ENGINE SPECIFICATION
GOVERNOR
MECHANICAL. SET AT NO LOAD 3300±100RPM
FIXED SPEED
VALVES
OHV INTAKE: MARTENSITE STEEL 4Cr10Si2Mo GB/T1221-1992
OHV EXHAUST: AUSTENITIC STEEL 5Cr21Mn9Ni4N GB/T1221-1992
VALVE SEAT
OHV INTAKE: IRON ALLOY INSERT
OHV EXHAUST: IRON ALLOY INSERT
CRANKSHAFT
EXTENSION:PER CUSTOMER REQUIREMENTS
CYLINDER
ALUMINUM W/CAST IRON BORE ADC12, P-V Casting Iron
1 Section 2 Specifications
2-2

Section 2 Specifications
LONCIN SNOW ENGINE SPECIFICATION
MODEL
G250F(D)S
CONNECTING ROD
ALUMINUM 51K
CHOKE
MANUAL CLICK-CLICK-CLICK
SPARK PLUG
F7RTC(RESISTOR TYPE)
CARBURETOR
FLOAT W/CHOKE AND PNEMATIC PRIMER, DUSTPROOF CAP, Limited
Mixture Adjustment
Ruixin
FILLER LOCATION
STANDARD LOW MOUNT. W/DIPSTICK. Only one at the cylinder head side.
DRAIN LOCATION
FRONT, UNDER THE CYLINDER HEAD. Standard.
PISTON RINGS
1,COMPRESSION
2,COMPRESSION
3,OIL CONTROL
STARTER
RECOIL AT 8 O'CLOCK POSITION
FUEL TANK
MANUAL CLICK-CLICK
FLYWHEEL
WITH RING GEAR
OIL SEAL
OBM
AIR CLEANER
WITHOUT FILTER
CYLINDER Shield
ADDED SHIELD
MUFFLER
STANDARD WITH GUARD
ENGINE KILL SWITCH
KILL SWITH
DECALS
EPA/CARB DECAL, LONCIN LOGO, EXTRA ONE
2-3

Section 2 Specifications
2.2 Dimensional drawings
G250F(D)S
2-4

Section 3 Maintenance
2.3 P.T.O Dimensional drawings
B4轴/ Type B4
2-5

Section 3 Maintenance
3、Maintenance
3.1 Maintenance schedule ---------------------------------------3－2
3.2 Engine oil --------------------------------------------------------3－2
3.3 Spark plug -------------------------------------------------------3－4
3.4 Valve clearance ------------------------------------------------3－5
3.5 Governor ---------------------------------------------------------3－6
3.6 Fuel filter -------------------------------------------------------- 3－7
3
3-1

Section 3 Maintenance
3.1 Maintenance schedule
(1) Service more frequently when used in the dust areas.
3.2 Engine oil
Drain the oil while the engine is warm to
assure rapid and complete draining.
1. clean the area around the oil filler
cap/dipstick and oil drain bolt. Remove the
oil filler cap/dipstick.
2. drain the engine oil into a suitable
container using one of the following
methods.
Oil drain bolt method:
a. remove the oil drain bolt and sealing washer and allow the oil to drain into a suitable
container.
b. after draining, install the drain bolt with the sealing
washer and tighten it securely.
Oil filler tube method:
In certain applications, it may be possible drain
the engine oil from the oil filler tube.
a. turn the fuel valve to the OFF position.
b. Remove the oil filler cap/dipstick.
c. Tip the engine and allow the oil to drain
from the oil filler tube into a suitable container.
REGULAR SERVICE PERIOD
Performed at every indicated month or
operating hour interval, whichever comes
first.
Each
use
First
month or
20 Hrs.
Every 3
months or
50 Hrs.
Every 6
months or
100 Hrs.
Every
year or
150Hrs.
ITEM
●
Engine oil
Check level
○
Change
○
○
●
Sediment Cup
Clean
○
●
Spark plug
Check-Clean
○
Replace
○
●
Idle speed
Check-Adjust
○(1)
●
Valve clearance
Check-Adjust
○(1)
○(1)
●
Fuel Tank
Clean
○(1)
●
Fuel Filter
Replace
○(1)
●
Combustion chamber
Clean
After every 150 Hrs. (1)
●
Fuel line
Check
Every 2 years (Replace if necessary) (1)
1 Section 3 Maintenance
3-2
FILLER CAP
DRAIN BOLT
FILLER CAP/DIPSTICK