CFMoto ATV CF500/CF500-A. Service Manual

15. Engine Removal, Inspection & Installation

CVT Case

Remove bolt 1 of CVT case

Remove nut 2 of CVT case

Remove outer clutch face and CVT case

Remove dowel pin, front and rear gasket

Clutch

Remove one-way clutch

Remove clutch shoe fixing nut with special tool

Remove clutch shoe.

Note:

The clutch shoe nut has left-hand threads.

Timing Chain

Remove timing chain

15-10

15. Engine Removal, Inspection & Installation

Engine Center

Gear position bolt

Remove gear position bolt 1

Remove spring and steel ball

Right

Crankcase

Remove left crankcase bolts

Remove right crankcase bolts

Separate right crankcase with special tool

Caution

The Crankcase separator plate

should be parallel with the end face
of crankcase

Crankshaft should remain in the left

crankcase half.

Tool:

Crankcase separator

Driven Bevel Gear, Front Output Shaft

Remove bevel gear cover bolt

Remove driven bevel gear

③

Remove front output shaft nut

④

15-11

15. Engine Removal, Inspection & Installation

Remove Oil seal

①

, Bearing limit nut

①

Remove Front Output Shaft

④

Shift Cam, Fork/Shaft

Remove Shift Cam

⑤

, Fork /Shaft

⑥

Drive Bevel Gear

Remove left crankcase from driven bevel gear

Drive Shaft, Drive Shaft

Remove drive shaft

⑦

and driven shaft

⑦

Balancer Shaft

Remove balancer shaft

5-12

15. Engine Removal, Inspection & Installation

Crankshaft

Separate crankshaft from left crankcase with special

tool

Tool: Crankshaft Separator

Oil bump, Relief Valve

Remove oil bump and relief valve

15-13

15. Engine Removal, Inspection & Installation

Engine Components Inspection

Cylinder Head Cover

Disassembly
Caution:

Each removed part should be identified to its

location, and the pars should be laid out in groups
designated as “Exhaust”, “Intake”, so that each will be
restored to the original location during assembly.

Remove rocker arm shaft bolts A

Remove rocker arm shaft by using M6 bolts B

Cylinder Head Cover Distortion

Clean off sealant from the fitting surface of cylinder head
cover, place cylinder head cover on a surface plate and
measure distortion with a thickness gauge.

Cylinder head Cover Distortion
Limit:

0.05mm

Tool:

Thickness Gauge

Distortion out of range:

→

Replace

Note:

Cylinder head cover and cylinder head should be

replaced together.

Rocker Arm Shaft

Measure out diameter of rocker arm shaft with a

micrometer.

Rocker Arm Shaft O.D.: (IN, EX)
Limit:

11.973~11.984mm

Tool: Micrometer (0~25mm)

15-14

15. Engine Removal, Inspection & Installation

Rocker Arm

When checking the rocker arm, check the inner

diameter of the valve rocker arm and wear of the
camshaft contact surface.

Rocker Arm I.D. :

.000~12.018mm

Tool:

Dial Calipers

Assembly

Note:

Intake rocker arm shaft A has oil holes.

Apply engine oil to rocker arms and shafts;

Install rocker arms and tighten rocker arm shaft to

the specified torque:

Rocker Arm Shaft Bolt: 28N.m

Cylinder Had

Disassembly

Remove intake pipe

Remove water temperature sensor

①

and

thermostat cover

②

15-15

15. Engine Removal, Inspection & Installation

Remove

thermostat

Compress the valve spring and remove valve cotter

with tweezers.

Tools: Valve Spring Compressor

Tweezers

Remove valve spring upper seat and valve spring

Remove valve from the other side.

Remove valve stem seal ring and valve lower seat.

15-16

15. Engine Removal, Inspection & Installation

Cylinder Head Distortion

Clean off carbon deposit from combustion chamber;
Check the gasket surface of the cylinder head for
distortion with a straightedge and thickness gauge. Take
clearance readings from several places. If any clearance
reading is out of the service limit, replace with a new
cylinder head.

Cylinder Head Distortion Service Limit: 0.05mm

Tool: Thickness Gauge

Valve Seat Width

Coat the valve seat with color uniformly. Fit the

valve and tap the coated seat with the valve face in
a rotating manner. To get a clear impression of the
seating contact, use a valve lapper to hold the valve
head.

The ring-like dye impression on the valve face

should be continuous, without any break. The width
of the dye ring, which is the visualized seat width,
should be within the following range:

Valve Seat Width: 0.9-1.1mm
Tool: Valve Lapper

Valve Stem and Valve Guide

Lift the valve about 10mm from valve seat. Check

the valve stem deflection in the directions of X and Y
perpendicular to each other, with a dial gauge. If the
deflection measured is out of the limit, replace either
the valve or the valve guide. (If the valve stem is
worn to the limit and the clearance is found to be in
excess of the limit, replace the valve. If the valve
stem is within the limit, replace the valve guide.
Double check the clearance after replacing the
valve stem or the guide).

Valve Stem Deflection (IN & EX): 0.35mm
Tool:

Micrometer

Magnetic Stand

15-17

15. Engine Removal, Inspection & Installation

Valve Stem O.D

Measure valve stem O.D with a micrometer

Service Limit
IN: 4.975-4.990mm
EX: 4.955-4.970mm
Tool:

Micrometer (0-25mm)

Valve Stem Run-out

Support valve stem with V block as illustrated on the

right. Check the run-out with a dial gauge.

Service Limit: 0.05mm
Tool: Magnetism Stand

Dial Gauge (1/100)
V block

Valve Head Radial Run-out

Measure the valve head radial run-out as illustrated

on the right.

Valve head Radial Run-out out of range:

→

Replace

Service Limit: 0.03mm
Tool:

Dial Gauge (1/100)

Magnetic Stand
V Block

Valve Face Wear

Check each valve face for wear or damage.

Replace valve with a new one if it is found to have
abnormal wear. Measure valve head thickness T.

Valve head thickness T out of range:

→

Replace

Service Limit: 0.5mm
Tool: Vernier Caliper

Valve Stem End

Check valve stem end for pitting or wear. In case of

any pitting or wear, resurface the valve stem end. If
the length T is less than service limit, replace valve
with a new one.

Valve Stem End Length

Service Limit: 2.1mm
Tool: Vernier Caliper

15-18

15. Engine Removal, Inspection & Installation

Valve Spring

Valve Spring keeps valve and valve seat tight.

Weakened spring results in reduced engine power
output and chattering noise from valve mechanism.

Measure the spring free length.

Spring free length out of range:

→

Replace

Service Limit: 38.8mm
Tool

Vernier Caliper.

Measure the force to compress the spring to the

specified length.

Valve spring tension out of range:

→

Replace

Service Limit: (IN/EX)

182N-210N/31.5mm

Tool: Spring Scale.

Measure valve spring incline.

Spring incline out of range:

→

Replace

Valve Spring Incline Limit: 2.5º/1.7mm

Assembly of Cylinder Head

Install each valve spring seat;

Apply moly oil to valve stem seal and fit into

position.

Material: Moly oil

Note:

Do not reuse the valve stem seal.

Insert the valves, with stems coated with moly oil all

around.

Note:

When inserting the valve, be careful not to

damage the lip of the stem seal.

15-19

15. Engine Removal, Inspection & Installation

Install valve spring with small-pitch end “b” facing

cylinder head. Big-pitch end “a” is marked.

Put on the valve spring retainer. Use the valve

spring compressor to press down the spring. Fit the
two cotter halves to the stem end and release
compressor to allow the cotter

①

to wedge in

between seat and stem. Make sure that the rounded
lip

②

of the cotter fits into the groove

③

in the stem

end.

Tool:

Valve Spring Compressor

Tweezers

NOTE:

Knock the valve end with rubber

hammer. Make sure valve cotter is
fit into groove.

Check the sealing effectiveness of cylinder head.

Dip clean solution into valve IN/EX

①

and check

for any leakage of valve seat

②

after a few

minutes.

15-20

15. Engine Removal, Inspection & Installation

Install

thermostat

Install

thermostat

cover

Install water temperature sensor, apply thread

locker to the thread part, tighten it to the
specified torque.

Water temperature sensor

Tightening torque: 10 N·m

Install intake pipe, apply lubricant to 0-ring.

Camshaft

Check camshaft for wear and run-out of cams and
journals if the engines produces abnormal noise or
vibration or lacks power output. Any of these symptoms
could be caused by wear of camshaft.

Note:

Do not try to disassemble the camshaft/automatic

decompression assembly. It is not serviceable.

15-21

15. Engine Removal, Inspection & Installation

Automatic Decompression

Move the automatic decompression weight with

hand and check if it is operating smoothly. If it is
not working smoothly, replace with a new
camshaft/automatic decompression assembly.

Cam Wear

Worn cams can often cause mistimed valve

operation resulting in reduced power output. The limit of
cam wear is specified for both IN and EX cams in terms
of cam height “a”. Measure with a micrometer the cam
height.
Cam height out of range:

→

Replace

Cam height service limit:
IN: 33.130mm

EX: 33.200mm

Tool

micrometer (25-50mm)

Camshaft Journal Wear

Check whether each journal is worn to the limit by

measuring camshaft journal oil clearance with the
camshaft installed.

Camshaft journal oil clearance
Service limit: 0.15mm

Check according to the following steps:

Clean off materials from cylinder head and cover;

Install camshaft with plastic gauge;

Install cylinder head cover and tighten bolts evenly

and diagonally to the specified torque:

Tightening torque: 10 N·m

Remove cylinder head cover, read the width of the

compressed plastic gauge with envelop scale. The
reading should be taken from the widest part.

Tool:

Plastid Gauge

Note:

Do not turn the camshaft with plastic gauge in

place.

If the camshaft journal oil clearance exceeds the limit,

measure the outer diameter of camshaft;

Replace either cylinder head set or the camshaft if the

clearance is not correct.

15-22

15. Engine Removal, Inspection & Installation

Camshaft Journal O.D.

Measure camshaft journal O.D. with a micrometer.

If the O.D. is out of range, replace camshaft with a
new one.

Camshaft journal O.D. service limit:

Sprocket end: 22.959 mm—21.980mm
Other end: 17.466mm—17.484mm

Tool: micrometer (0-25mm)

Camshaft Run-out

Measure the run-out with a micrometer. Replace

camshaft is the run-out is out of range.

Service limit: 0.10mm

Timing Sprocket and Chain

Check timing sprocket and chain for wear or

damage.

Replace with new parts if abnormal wear or damage

is found.

Tensioner and Chain Guide

Check contact surface of tensioner and chain guide

for wear and damage.

Replace with news parts if abnormal wear or

damage is found.

15-23

15. Engine Removal, Inspection & Installation

Chain Tensioner
Inspection

Check tensioner for any damage or poor function.

Damage, poor function:

→

Replace

Insert screw driver into the slotted end of adjusting

screw, turn it clockwise to loosen the tension and
release the screwdriver.

Check the push rod movement. If the push rod is

stuck or there is a failure with spring mechanism,
replace the chain tensioner with a new one.

Cylinder
Cylinder Distortion

Check the gasket face of cylinder for distortion with

a straightedge and thickness gauge and take
clearance readings at 7 points as illustrated. If the
largest reading at any of the 7 points of the
straightedge is out of the range, replace the
cylinder.

Cylinder Distortion Service Limit: 0.05mm
Tool: Straightedge
Thickness Gauge

Cylinder Bore

Check cylinder wall for scratches, nicks or other

damage. Replace with a new one if any.

Measure cylinder bore diameter at three points of

upper, middle and lower.

Standard Cylinder Bore: 87.500-87.522mm
Tool: Cylinder Gauge Set

15-24

15. Engine Removal, Inspection & Installation

Piston
Piston Diameter

Use a micrometer to measure the diameter at the

point 10mm above the piston end, as illustrated on
the right. If the measurement is less that the limit,
replace the piston

Standard: 87.460-87.480mm
Limit: 87.380mm

Tool: Micrometer (75-100mm)

Calculate the piston to cylinder clearance according

to the above measurement.

If the clearance is more than 0.15mm, replace the

cylinder or piston, or both.

Piston Ring to Groove Clearance

Use a thickness gauge to measure the side

clearance of top

ring and 2

ring.

If the clearance exceeds the limit, replace both

piston and piston rings.

Service Limit:
Top ring: 0.18mm
2

ring: 0.15mm

Standard width of piston ring groove
Top ring: 1.03-1.05mm
2

ring: 1.22-1.24mm

Oil ring: 2.51-2.53mm

Standard thickness of piston ring
Top ring: 0.970-0.990mm
2

ring: 1.170-1.190mm

Tools: Thickness gauge

Micrometer (0-25mm)

15-25

CFMoto ATV CF500/CF500-A. Service Manual - part 11