Yamaha XS850G Specifications download pdf (Page 47)

2.Valve

lifter

a.

Checkeach

valve

lifter

forscratchesor other

damage.Ifthelifter

is

damaged

in

anyway,

the cylinder headsurface

in

which

it

rides

is

probablyalsodamaged.Ifthe damage is severe,

it

maybenecessary

to

replaceboththelifter

and the cylinderhead.

NOTE:Forpropervalvelifter

-

to

-

headclear

-

ance,always

install

lifterson their original

valves.

E.Camshafts,CamChain and CamSprockets

1.

Camshaft

a.

Thecamlobe metal surfacemayhave

a

blue

discolorationduetoexcessivefriction.The

metalsurfacecouldalso

start

toflakeoffor

becomepitted.

NOTE: Theexhaustcamappearsdarkerthan

theintakecam.This

is

due

to

a

specialhard

-

eningprocessand

is

notduetoexcessive

enaine

heat.

b.Ifanyoftheabovewearconditions are readily

visible,thecamshaftshouldbereplaced.

c.

Even

thoughthecamlobesurfaceappearsto

beinsatisfactorycondition,thelobesshould

bemeasuredwith

a

micrometer.Camlobe

wear can occurwithoutscarringthesurface.

Ifthiswearexceeds

a

pre

-

determined amount,

valvetimingand

lift

are

affected.Replacethe

camshaft

if

wearexceedsthelimits.

d. Installthecamshaftonthecylinderhead.

Place

a

stripofPlastigaugebetween camshaft

andcamshaftcap

as

illustrated(lengthwise

along camshaft). Tightenthenutswith

specified torque. Removethecamshaftcap

anddeterminetheclearancebymeasuring

thewidthoftheflattenedPlastigauge.

I

PLASTIGAUGE

I

CAMSHAFT

CYLINDER

HEAD

STUDS

FORCAMSHAFTCAP

CapNutTightening Torque:

0.8~1.0m-kg(5.8~7.2ft-lbs)

NOTE: Donotturncamshaftwhenmeasuring

clearancewithPlastigauge.

Camshaft

-

to

-

capClearance:

Standard:.020~.054mm(.0008~.0021")

Maximum:

0.160mm

(.006")

Ifcamshaft

-

to

-

capclearanceexceedsspecifica

-

tion,measurecamshaft bearing surface diam

-

eter.

Bearing Surface Diameter:

Standard:24.97~24.98mm (0.9830~0.9835")

1)Ifcamshaft diameter

isless

thanspecifica

-

tion,causingexcessive clearance, replace

camshaft.

2)

If

camshaft

is

withinspecificationandcam

-

shaft

-

to

-

capclearance

is

excessive,replace

cylinderhead.

2.CamChain

Exceptincasesofoilstarvation,thecamchain

wearsvery

little.

If

thecamchainhasstretched

excessively and

it

is

difficulttokeepthe pro

-

percamchain tension, thechain

should be

replaced.

3. CamSprockets

Checkcamsprocketsforobviouswear.Ex

-

aminedampingrubberonsidesofcam

sprockets.

If

thedamping rubber

is

disintegrat

-

ing,thesprocketshouldbereplaced.Damaged

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