KAYO MOTOR AT125-B User manual

ZHE JIANG KAYO MOTOR CO., LTD
www.RideKayo.com
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Model AT125-B
Service Manual

ZHE JIANG KAYO MOTOR CO., LTD
www.RideKayo.com
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Instruction
This manual contains detailed information for Kayo AT125-B (ATV), maintenance,
adjustments, disassembly, installation, inspection points and specifications.
Please read the manual carefully and follow the instructions closely when performing
inspections and repairs, this will increase the reliability, performance and overall
lifespan of the vehicle.

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Contents
Chapter 1 Maintenance information
Chapter 2 Plastics and Body parts
Chapter 3 Regular Maintenance and adjustment
Chapter 4 Outer parts of engine
Chapter 5 Engine internals
Appendix Electrical schematic diagram
ZHEJIANG KAYO MOTOR CO., LTD.
All contents in this manual are subject to improve and
update without notice.

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Conversion table
Item
Unit Conversion
Pressure
1kgf/cm2=98.0665kPa；1kPa=1000Pa
1PSI=0.0689kgf/cm2
1mmHg=133.322Pa=0.133322kPa
Torque
1kgf·m=9.80665N·m
Volume
1mL=1cm3=1cc
1L=1000cm3
moment
1kgf=9.80665N
Length
1in=25.4mm
Danger/warning/attention
Take the following warnings seriously, it’s important for regular maintenance,
especially important during engine maintenance.
Danger: Be on high alert for danger.
Warning: Be on alert for moderate danger.
Attention: Be on alert for minor danger.
This manual may contain some potential risks when performing engine work and
maintenance, please pay close attention to the above explanations, Service technician
or mechanics should have basic mechanical knowledge before performing any service,
maintenance, or inspection.
1. Service Information
1.1 Warnings 1.5 Torque tightening
1.2 VIN Number 1.6 Lubricant, sealant
1.3 Main parameters list 1.7 Cable, hose and wiring diagram

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1.4 Maintenance parameters list
1.1 Safety precautions
Safety first
1. Wearing work clothes (coveralls), hat and safety boots suitable for the operation.
In some condition’s safety glasses, dust masks, gloves and other safety protective
supplies are needed to protect you from injury.
2. Do not run the engine in unventilated places.
3. To prevent burns, do not touch the engine or exhaust until cooled.
4. Battery solution (dilute sulfuric acid) is a strong corrosive agent; contact with the
skin, contact with eyes may cause blindness. If the battery solution accidentally
touches clothes or skin, rinse immediately with clean cold water. If the battery
solution is touches eyes, please flush immediately with plenty clean cold water and
get medical treatment as soon as possible. Battery and battery solution should be kept
out of reach of children. Battery charging will produce flammable and explosive gases,
if exposed to a source of fire or spark there is a risk of explosion or fire. Please charge
in well-ventilated places.
5. As gasoline is flammable and explosive. Pay attention to sparks as well as open
flames. Vaporized gasoline may explode if exposed to open flame or sparks, please
choose well-ventilated areas away from these hazards when refueling.
6. Attention, the rear wheel, clutch or sprockets and other rotating parts and
movable parts as hands and clothes may be caught during maintenance.
Disassembly and installation precautions
1. All Parts, lubricants oils and fluids must be Kayo brand parts or Kayo recommends.
2. During disassembly, please sort and separate out the parts and fasteners of each
system to ensure that everything is put back together properly.
3. Clean the vehicle or parts to be serviced before inspection.
4. Gaskets, o-rings, piston pin, piston ring, cotter pin and other one-time use parts
must be replaced after disassembling.
5. Snap rings can be deformed if opened too much during disassembly. DO NOT
re-use deform snap rings.

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6. After disassembly and inspection, clean parts and blow the cleaning agents away
with compressed air before measuring. Grease the moving surfaces before assembly.
7. During disassembly, check all the necessary specifications and measure according
to directions in this manual. Make sure measurements and conditions are within
specification.
8. Bolts, nuts, screws and other fasteners shall be pre-tightened and then tightened in
accordance with the specified torque in a diagonal sequence. From large to small, and
from inside to outside.
9. Inspect all rubber parts during disassembly and replace if necessary. In addition, as
some rubber pieces are not resistant to corrosive materials, please keep them from
contacting volatile oils, grease, or liquids.
10. Pack or inject recommended grease in specific places as stated in service manual.
11. Use special tools when needed for disassembly and installation.
12. Ball bearings can be rotated with finger to confirm whether the rotation is flexible
and smooth.
Bearing axial and radial clearance is oversized.
Clean and grease bearings with a tight spot when rotated. If the bearings still feel
stuck after cleaning, replace. If the bearings can’t be cleaned, replace.
If the bearing is a press fit, and becomes deformed after disassembling, replace it.
13. Bearings should be lubricated or packed with grease before assembly. Take note
of the direction of installation when assembling. When installing open or double-sided
dustproof bearing, make the manufacturer's logo and dimensions outwards.
14. Let the chamfered side towards force direction when install the Snap-ring. Do not
use the rings without elasticity. After assembly, rotate the snap-ring to confirm that it
is firmly installed in the slot.
15. It’s important to check that all fastening parts are tightened and that functions are
normal after assembling.
16. Brake fluid and coolant can damage surfaces, painted parts, plastic parts, rubber
parts, etc., do not let brake fluid contact to these parts, If brake fluid contacts these
parts rinse and dilute with water immediately.

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17. When installing oil seals manufacturer’s mark and sizes face outward.
Check the oil seal before using.
Grease the oil seal lip before assembly.
18. When installing rubber hose parts, insert the rubber pipe into the fitting. If there is
a hose clamp, install the hose clamp in the hose indentation. Replace rubber hoses if
dried, cracked, or deformed
19. Clean all gasket material from surfaces of before installing new parts or
reassembling.
20. Do not bend cables excessively. Kinked or damaged cables may cause poor
response and inner cables to fray and eventually break.
When assembling any protective caps, covers or boots make sure they are seated
correctly in the respective grooves.
Engine Break-in
Proper Engine break in is necessary on new engines and newly rebuilt engines
to help ensure that longevity and reliability of the engine components.
Recommended break-in time is 20 hours, as follows:
0~10 hours: Operate at no more than ½ throttle, keep gear changes and speed
variances to a minimum. Do not operate for extended amounts of time with a fixed
throttle position. Let the engine cool for 5 to 10 minutes after each hour of operation.
Avoid quick acceleration.
0~20 hours: Operate at no more than 3/4 throttle, Do not operate for extended
amounts of time with a fixed throttle position. Change gears and vary speeds as
necessary. Let the engine cool for 5 to 10 minutes after each hour of operation. Avoid
quick acceleration.
Note:
During break-in period, inspect for noises and wear and follow maintenance
schedule.
After Break-in period is complete schedule the unit for an inspection and service.

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1.2 VIN Number
Model
HY110AT（AT125-B）
VIN number
Engine number
1 VIN number
2 Name plate
3 Engine Number
1
1.3 Specifications, Model information
No.
Item
3
2
1

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1
Brand
KAYO
2
Type
AT125-B
3
Name
125cc utilityATV
4
Company
ZHEJIANG KAYO MOTOR CO., LTD.
●Dimensions, Vehicle Specifications
No.
Item
1
Starting type
Electric
1
Dimension（L*W*H）（ mm）
1380*880*930
2
Handlebar height（mm）
930
3
Handlebar width（mm）
730
4
Rear fender height（mm）
700
5
Seat height （mm）
635
6
Min. ground clearance（mm）
90
7
Wheelbase（mm）
900
8
Front width outside of tires
（mm）
700
9
Rear width outside of tires （mm）
640
10
Turning radius（mm）
1650
11
Turning angle（degree）
38°±2°
12
Net weight（Kg）
97.4±2
13
curb weight（Battery+Fuel）（ Kg）
102
14
Max. Speed Km/h
(Speed limitation) 40

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2
Engine type
Horizontal Single cylinder, four stroke, air
cooling
3
Air distribution
SOHC/Chain drive
4
Cylinder diameter × stroke（mm）
52.4*49.5
5
Compression ratio
9.0 :1
6
Lubrication mode
Pressure + splash lubrication
7
Oil pump type
Rotor type
8
Lubricating oil filter type
Full flow filter rotary, Paper filter core
9
No. of Engine oil
SAE15W-40
10
Cooling
Air Cooling
11
Coolant
/
12
Air filter
Sponge filter cartridge
13
Carburetor
Flat suction plunger type （JINGKE
PZ22/EPA）
14
Tank volume
2L
15
Clutch type
Dry automatic clutch
16
Variable speed mode
1+1 Foot shifting, with shift protection.
17
Gear range
One forward gear, one reverse gear
18
Shift type
R~N~D
19
Deceleration
ratio
Forward Gear D
Reverse Gear R
Primary
Deceleration ratio
Clutch hub gear / primary transmission tooth
Single stage
deceleration ratio
Forward gear ratio
Forward gear ratio
Total speed ratio
●Frame
20
Driving sprocket ratio
37/13

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21
Output type
Chain drive, rear wheel drive
22
Brake type
Front and rear disc brake
23
Suspension type
Double rocker independent type
24
Frame type
Welded steel tube sheet
●Engine Specifications
●Lubrication system
Item
Standard
Limitation
Engine oil
capacity
Changeoil
800mL （ No oil filter replaced ）
－
Changeoil
800mL （ oilfilterreplaced ）
Full capacity
800mL
－
Recommended engine oil (Original)
·four-strokesmotorcycles SAE-15W-40
·For replacements, it must be within
following scope:
·API classification ： SGor upper grade engine
oil
·SAE specification ： refer to left table
Oil pump rotor
Internal and external rotor
clearance
0.07 mm～0.15mm
0.2mm
Clearance between outer rotor
and box
0.03 mm～0.10mm
0.12mm
Oil pump rotor end clearance
0.023 mm ～ 0.055mm
0.12mm
Oil pressure
1500r/min，90℃时200 kPa ~400kPa
Generally, 240 kPa
6000r/min, 90℃ 600 kPa ~700kPa，
Generally, 600 kPa
●Air intake system（see engine section）
●Oil cooling device Mesh oil cooler
●Wheel (front and rear wheels)
Item
Standard
limited
Viscosity
grade
Tempretuare

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Rim jump
Vertical
1.0mm
2.0mm
Horizontal
1.0mm
1.8mm
Tire
Thread
~
3.0mm
Air Pressure
4.0 PSI
~
●Brake system
Item
Standard
limited
Front brake
disc thickness
3.5mm
3mm
Brake lever stroke
5~10mm
~
Braking force
400N*m
~
Rear brake
disc thickness
3.5mm
~
Brake lever stroke
10~20mm
~
Braking force
500 N*m
~
●Ignition device
Item
Standard
Ignition method
CDI electric ignition
Sparking plug
Type
Resistor type spark plug
Standard
ATR7C/（torch）
Gap
0.6~0.7mm
Spark character
>8mm,1 bar
Spark advance angle
Ignition coil
resistance
Primary
0.43~0.57Ω
Secondary
10.1~11KΩ
Peak voltage
Primary ignition
coil
>150Vac

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Pulse
2Vac
●Light / Instrument / Switch
Item
Standard
Accessory inline fuse
15A
Light
Headlight
12V*3W*2
Taillight / brake
light
LED
Gear Indicator
LED
●Valve mechanism + cylinder cover（see engine section）
●Cylinder + piston + piston ring + crank connecting link（see
engine section）
1.4 Fastener Torque Specifications
Note: When installing threads, please manually attach 2~3 turns of thread first.
Torque Specifications chart
No.
Item
Install position
Bolt
specification
Grade
Torque
N*m
1
Engine
Lower mounting
bolt
M8
10.9 Grade
37~50
2
Upper mounting
bolt
M8
10.9 Grade
37~50
3
Bottom
mounting bolt
M8
8.8 Grade
18~25
4
Suspension
Brake bolts
M10*1.25
8.8 Grade
35~45
5
A-arm bolts
M10*1.25
8.8 Grade
35~45
6
Rear swing arm
bolt
M10*1.25
10.9 Grade
58~71
7
Shock bolts
M12*1.25
8.8 Grade
50~60

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8
Brake
Rear disc
M8
8.8 Grade
18~25（with
blue thread
sealants）
9
Front disc
M6
10.9 Grade
15~20
10
Caliper
M8
10.9Grade
29~35
11
Front Brake Tee
M8
8.8
18~25
12
Rear Axle
Rear Axle
M12*1.25
8.8
55~65
13
Nut
M27*1.5
80~90
14
Chain bolt
M6
8.8
8~12
15
Turning
Handlebar
clamps
M8
10.9
18~25
16
Steering column
bolts
M8
8.8
18~25
17
Handlebar riser
bolt
M10*1.5
10.9
50~60
18
Electrical
components
Battery Box
M8
8.8
15~20
19
Muffler
M8
8.8
15~20
20
Voltage
regulator
ignition coil
M6
8.8
7~11
21
Fuel tank,
body parts,
plastic
Fuel Tank
M6
8.8
7~11
22
Fuel Tank
Switch
M6
8.8
7~11
23
Pegs,
floorboards
M8
8.8
18~25
24
Brush guards
M6
8.8
8~12
25
Plastic screw
TM6
7~11
26
Screw for
headlight and
plastic
ST4.2
3~5

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●Tightening moment at specified position - engine（see engine
section）
●Engine service tool（see engine section）
●Engine special tool（see engine section）
1.5 lubricating grease and sealant
No.
Smear Position
Function
Grease
1
Dust cap for rocker arms
Lubrication
XHP222
2
Ball joints of rocker arms
3
Steering column bottom
4
steering knuckle/spindle and
wheel hubs
5
Pivot bolts (swing arm, a-arms)
6
Bushings, Bearings
7
Rear axle liner bushings, tubes
8
Rear axle bearing and oil seal
9
Steering column clamp
Note: please coat inside of handlebar grip with grip glue before
installing.
Engine operating materials and installation accessories (see engine
section) Engine operating materials include lubricating oil (engine oil),
Grease and may require thread sealant or thread lock.

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1.6 Wiring and cable Routing diagrams
Main Harness
Front brake line
Throttle Cable
Rear brake line
Choke cable

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Headlight connector
Combination switch connector
Key switch
Reverse indicator connector
Neutral indicator connector
Kill switch connector
Brake cable connector
Positive
battery
cable
Negative
battery cable
Stator connector
Gear display connector
Rectifier regulator connector

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Ignition
Coil
CDI
Rectifier
Regulator
Tail
light

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2 Plastic body
2.1 Maintenance warnings
2.2 Installation torques
2.3 Seat, front guard, hood, rear body, left and right guard, plastics foot guards,
dismounting left and right footpegs
2.1 Maintenance cautions
Operation cautions
1. When replacing plastics parts, please install new warning labels, stickers and
riveted tags to the new plastics.
This chapter is about the dismounting the body plastics.
2.2 Installation torque
M8 bolt：18~25N*m
TM6 bolt ：7~11 N*m
M6*bolt：8~12 N*m
2.3 Hood, handlebar, seat, plastic parts (rear body, front body and
middle guard), front guard, plastic pedals
2.3.1 Hood
Disassembly
1. Remove the bolts 1 and 2.
2. Push down and gently pull the hood
forward to remove. (Be careful as the
tabs are easy to break)
Installation: In reverse order of
disassembly. Locate tabs into slots and
push to lock into place then install bolts

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1 and 2 (note: replace hood plastic if any
of the tabs broke during disassembly)
2.3.2 Handlebar
Disassembly
1. Cut off power first. (disconnect
battery)
2. Cut plastic cable ties, then disconnect
the combination switch, stop switch and
remove right grip.
3. Release the handle bolt of the disc
brake with the tool and remove the brake
handle.
4．dismantling the front brake and rear
brake.
5．Pull out the air door line according to
the graphic direction, then remove the
choke cable.
6．Screw the accelerator cap bolts with
tools and remove the throttle cable.
7. Remove the pressing bolts, remove
the upper block and remove the handle
bar.
1/2
Combination switch
Rear Brake
Front Brake
Throttle
Choke lever
Kill Switch