Norton Commando 750 (1972), Commando 750 (1970), Commando 750 (1974), Commando 750 (1973), Commando 750 (1975) Owners Workshop Manual

Norton

Commando
Owners
Workshop

Manual

by

Jeff

Clew

(with

an

additional

chapter

on

the

electric

start

models by

Stewart

Wilkins)

Models Covered:

Commando.

745cc.

February

1968

to

March

1969

Commando

Fastback. 745cc. March

1969

to

March

1973

Commando Roadster. 745cc. March

1970

to

October

1973

Commando

Hi-Rider.

745cc.

May

1971

to

October

1973

Commando Interstate. 745cc. January

1972

to

October

1973

Commando

8~0

Roadster. 828cc.

April

1973

to

October

1977

Commando

850

Hi-Rider. 828cc. April

1973

to

February

1975

Commando

850

Interstate. 828cc.

April

1973

to

October

1977

ISBN

0 85696 125 6

© Haynes Publishing Group

1990

All

rights reserved. No

part

of

this

book

may

be

reproduced

or

transmitted

in

any

form

or

by

any

means,

electronic

or

mechanical,

including

photocop~ing.

recording

or

by

any

information

storage

or

retrieval system,

without

permission

in writing

from

the

copyright

holder.

Printed

in

England. (125 - 6P9)

Haynes

Publishing

Group

Sparkford

Nr

Yeovil

Somerset

BA22

7JJ

England

Haynes

Publications,

Inc

861

lawrence

Drive

Newbury

Park

California

91320

USA

ABCOE

FGHU
KlMNO

PQR

..

2·

Acknowledgements

Our

grateful

thanks

are

due

to

Norton-Villiers Limited

for

technical assistance given

and

permission

to

use

many

of

their

illustrations. Brian Horsfall gave necessary assistance

with

the

overhaul

and

devised ingenio\ls

methods

for

overcoming

the

lack

of

service tools. Les Brazier

took

the

photographs

that

accompany

the

text.

Tim

Parker

edited

the

text.

Our

thanks

are also

due

to

Steve

Challis

who

kindly loaned us

the

750

cc

Commando

model

on

which

this manual is based

and

to

Arthur

Vincent

of

Vincent

and

Jerrom,

the

Norton-Villiers

dealer

in

Taunton,

who

provided

much

in-depth servicing

and

modification

information.

We

are also grateful

to

Fran

About

this

manual

The

author

of

this

manual

has

the

conviction

that

the

only

way

in

which a meaningful

and

easy

to

follow

text

can

be

written

is

first

to

do

the

work

himself,

under

conditions

similar

to

those

found

in

the

average household. As a result,

the

hands

seen

in

the

photographs

are

those

of

the

author.

Even

the

machines are

not

new;

examples

that

have covered a

considerable

mileage were selected,

so

that

the

conditions

encountered

would

be

typical

of

those

found

by

the

average

owner/rider.

Unless

specially

mentioned

and

therefore

considered essential,

Norton-

Villiers service

tools

have

not

been

used.

There

is invariably

alternative

means of loosening

or

slackening

some

vital

component,

when service

tools

are

not

available

and

risk

of

damage

is

to

be

avoided

at

all costs.

Each

of

the

chapters

is

divided

into

numbered

sections.

Within

the

sections are

numbered

paragraphs. Cross-reference

throughout

this manual is

quite

straightforward

and

logical.

When

reference

is

made,

'See

section

6.10',

it

means

section

6,

paragraph

lOin

the

same

chapter.

If

another

chapter

were

meant

Ridewood

and

Co,

of

Wells,

who

provided

the

Mark

3 Electric

Start

model used

for

the

photographic

sequences

in

Chapter

9,

and

to

Chris

Rogers

who

provided

the

850

Roadster

featured

on

the

front

cover

of

this

manual.

Finally, we

would

also like

to

acknowledge

the

help

of

the

Avon

Rubber

Company

who

kindly

supplied

illustrations

and

advice

about

tyre

fitting,

of

Amal Limited

for

the

use

of

their

carburettor

illustrations,

and

of

Automotive

Products

Limited

who

provided illustrations

and

advice

about

their

hydraulic disc

brakes.

it would say,

'See

Chapter

2, Section

6.10'.

All

photographs

are

captioned

with a section/paragraph

number

to

which

they

refer, and

are

always

relevant

to

the

chapter

text

adjacent.

Figure

numbers

(usually line illustrations)

appear

in

numerical

order,

within

a given

chapter.

'Fig

1.1'

therefore

refers

to

the

first figure in

chapter

1.

Left

hand

and

right

hand

descriptions

of

the

machines

and

their

components

refer

to

the

left

and

right

of

a given machine

when normally seated.

Motorcycle

manufacturers

continually

make

changes

to

specifications

and

recommendations,

and

these,

when

notified,

are

incorporated

into

our

manuals

at

the

earliest

opportunity.

Whilst every

care

is

taken

to

ensure

that

the

information

in

this

manual is

correct

no liability can

be

accepted

by

the

authors

or

publishers

for

loss, damage

or

injury caused

by

any

errors

in

or

omissions

from

the

information

given.

Contents

Chapter

Introductory

pages

l/Engine

2/Gearbox

3/Clutch

and

primary

transmission

4/Carburation

and

lubrication

5/lgnition

system

6/Frame

and

forks

7/Wheels.

brakes

and

tyres

BlElectrical

system

Metric conversion

table

Index

Section

I

ntroduction

to

the

Norton

Commando

Ordering spare

parts

Routine

maintenance

Recommended

lubricants

Safety

first!

English/American

terminology

Specifications

Dismantling
Examination

and

renovation
Reassembly
Fault

diagnosis

Specifications

Dismantling
Examination

and

renovation

Reassembly

Fault

diagnosis

Specifications
Adjusting

clutch

Examining

clutch

plate

and

springs

Examining

clutch

inner

and

outer

drums

Fault

diagnosis

Specifications

Dismantling
Examination
Balancing

carburettors

Exhaust

system
Lubrication
Fault

diagnosis

Specifications

Ignition timing

Plugs

Fault

diagnosis

Specifications
Front

fork
Swinging arm
Speedometer

and

tachometer
Cleaning
Fault

diagnosis

Specifications

Front

wheel

and

brakes
Master cylinder
Rear

wheel

and

brakes

Rear

chain

Tyres

Fault

diagnosis

Specifications

Battery
Lights
Ignition

Page

5

6

7

8

9

10

11
13

23

31
52

53
64

58
60

66

67
67
67
67

68

71
72
74
74
75
75
76

77
79

80

82

83

84
89
97
97
98

99

100

101

106

73

110

112

113

114
115
118

123

143

4

Model

dimensions:

Fastback Roadster

Interstate

Hi-Rider

850ee

Height:

40.75

in

40.75

in

40.75

in

50.25

in

40.75

in

(103.5 em)

(103.5

em)

(103.5

em)

(127.6

em) (103.5 em)

Length:

87.5

in

87.5

in

87.5

in

87.5

in

88.0

in

(222 em) (222 em)

(222

em) (222 em)

\223.7 em)

Width:

26.0

in

26.0

in

26.0

in

26.0

in

26.0

in

(66 em)

(66 em)

(66

em)

(66 em) (66 em)

Ground

6.0

in

6.0

in

6.0

in

6.0

in

6.0

in

clearance:

(15 em) (15 em)

(15em)

(15 em) (15 em)

Wheelbase:

56.75

in

56.75

in

56.75

in

56.75

in

58.0

in

(144 em)

(144 em)

(144

em) (144 em) (147em)

Weight

(dry):

395.4lb

395.41b

410lb

N/A

418

-430

Ib*

(197.3 kg)

(179.3 kg)

(186

kg)

(190 -

196

kg) *

*

Depending

on

specification

Introduction to the Norton Commando

In

the

immediate

post-war years, British

motor

cycle

manufacturers began

to

appreciate

the

advantages

of

a vertical

twin

engine, acknowledging

the

success of

one

manufacturer

who

had

succeeded

in marketing a highly

attractive

design as far

back

as

1937.

The

first

Norton

twin

was unveiled

at

the

1949

Earl's

Court

Show.

Of

497

cc

capacity it was

marketed

as

the

Model 7.

The

specification

included a

cast

iron engine with

splayed

exhaust

ports

and

push rods located in cast-in tunnels

at

the

front

of

the

cylinder

block.

The

magneto

and

camshaft

were driven by

separate

chains

that

formed

part

of

the

timing

gear assembly

and

were fully enclosed

within

a conventional

timing cover.

Norton

Roadholder

forks

looked

after

the

front

suspension;

at

the

rear

end

a 'garden

gate'

frame

layout

employed

plunger units characteristic

of

that

era.

As

time

progressed,

the

Norton

twins assumed

the

name

Dominator

and

the overall

specification

was changed

to

include alloy engine

components,

the

famous

Norton

'Featherbed'

frame

with

swinging

arm

rear suspension

and

shortened

Roadholder

forks.

Machines

fitted

with

the

'Featherbed'

frame were redesignated

the

Model

88

and

during

1956 a 596

cc

version,

known

as

the

Model

99,

was

added

to

the

range.

Sports

versions

of

both

models were

introduced

during

1962

and a 646

cc

machine

to

the

same basic

specification

that

was available in

both

standard

and

sports

trim.

Financial

problems

necessitated

Norton

Motors becoming

part

of

the

Associated

Motor

Cycles

Group

and

in

1962

the

old

Bracebridge

Street

works in Birmingham,

the

traditional

home

of

the

Norton,

finally closed when all

production

was moved

to

Woolwich.

Although

the

Norton

range of

motor

cycles was

continued,

some

hybrids

were

marketed

comprising in several

instances

Norton

engines

fitted

into

AMC cycle

parts.

The

twins

were, however,

the

least

affected,

apart

from

some

export

only

versions. It was

about

this

time

that

the

Norton

Atlas came

into

being,

fitted

with

an

enlarged

twin

cylinder

engine

of

745

cc.

It

too

ultimately

acquired

an

AMC

frame.

By

now

the

Bdtish

motor

cycle

industry

in general was faced

with

financial

problems, mainly

on

account

of

the

Japanese invasion

of

their

traditional markets_ Associated Motor Cycles were

one

of

several

manufacturers

to

collapse

under

the

strain

and

towards

the

end

of

1966 a satisfactory

arrangement

was

completed

for

their

assets

to

be

acquired

by Manganese Bronze Holdings

Limited,

of

which Villiers Engineering was a subsidiary_ A

new

company

was born - Norton-Villiers Limited

and

work

com-

menced

on

a design

project

under

the

direction

of

Dr

Stefan

Bauer

at

the

Villiers premises in Wolverhampton. Meanwhile,

Norton

production

was again

on

the

move,this

time

to

new

premises

on

one

of

the

trading

estates

at

Andover_ The move

was

completed

during

1969.

The

outcome

of Dr Bauer's

project

was

the

Norton

Commando, a 750

cc

vertical twin using

an

inclined version

of

the

original

Dominator

engine

suspended

in

an

entirely

new

frame

by

means

of

Isolastic stlspension

mountings, a patented

Norton-Villiers inventlon_

Although

initially dismissed by

the

sceptics as merely a revamped Atlas,

the

Commando

soon

found

favour

with

all who were privileged

to

have a

test

ride.

The

Isolastic suspension eliminated

the

high

frequency

vibration normally associated

with

the

vertical

twin

engine

and

gave a

hitherto

unknown

smooth

ride_

From

this

moment

the

Commando

became a success,

as

underlined

by

the

presentation

of

the

'Motor

Cycle

of

the

Year'

award

on

no

less

than

five consecutive years as

the

result

of

a reader

contest

organised

by

Motor Cycle News.

Six

versions

of

the

Commando

have

been

marketed,

the

Interstate,

designed

for

long distance

riding,

the

Roadster

for

normal

road

use,

the

Fastback,

virtually

the

original version,

the

Hi-rider,

built

in semi-chopper

style,

the

750

cc

Production

racer

and

the

Interpol,

a fully-equipped police

model used

by

many

police forces

throughout

the

world.

Only

the

Fastback

is no longer

in

production.

Further

permutations

are available

from

the

use

of

the

standard

or

the

Combat

engine,

the

latter

being a specially-tuned version

that

develops

65

bhp

at

7000

rpm

- 5

bhp

more

than

the

standard

engine_

During March

1973

an

850

cc

model

was

added

to

the

range,

fitted

with

a modified

form

of

the

750

cc

engine

that

has

the

same

power

output

but

imposes less stress on

the

more

vulnerable

components_

This

too

is

currently

available

in

five versions,

one

of

which

is

specially

equipped

to

give a significant

reduction

in noise level.

Perhaps

the

greatest success

of

the

Commando

was

Peter

Williams' Isle

of

Man

TT

win in

the

1973

Formula

750

race,

when a British

manufacturer

showed

that

a British

motor

cycle

could

still

offer

a serious challenge

and

emerge victorious.

The

Norton

Commando

is

indeed a superbi

ke

and

it

is

particularly

fitting

that

this descriptive

attribute

was

applied

to

the

Commando

when

interest

in large

capacity

high-performance

models

heightened

several years ago.

Modifications

to

the

Norton Commando range

When

the

Norton

Commando

was

announced

towards

the

end

of

1967,

it

was

greeted

with a certain

amount

of

scepticism

because

on

first

sight

it

appeared

to

comprise

of

the

old

Norton

Dominator

twin

cylinder

engine

mounted

at

an

inclined

angle in

a

set

of

new

cycle

parts.

It

was

not

realised

that

the

new

Isolastic

method

of

engine suspension

damped

out

all engine vibration

and

produced a machine

which

had

an

uncanny

smoothness

for

a vertical

twin.

In

due

course

the

critics were

silenced

and

the

Commando

had

the

distinction

of

being

regarded

as

the

first

of

today's

so-called

'Superbi

kes'.

There can be little

doubt

that

the

original design

concept

has

proved

correct,

since comparatively

few

modifications

of any

real

consequence

have been made since

production

commenced

during

1968.

Mostly

they

relate

to

styling

and

the

introduction

of

'slim line'

front

forks.

In

March

1973

the

750

cc

range

was

supplemented

by

the

introduction

of

an

850

cc

model,

the

engine

of

which embodies several design modifications

to

enable

the

same

power

output

as

that

of

the

750

cc

Combat

engine

to

be Obtained, with less stress

on

the

engine

components.

Today,

five variations of

the

basic

750

cc

model are available,

together

with five versions

of

the

850

cc

model. These include

the

Interpol

model which

is

used

by

police forces

throughout

the

world.

Some

of

the

engine

and

gearbox

data

contained

in

this

manual can

be

applied

to

the

earlier

Dominator

twins

of

497

cc

and

597

cc, also

to

the

646

cc

twins

and

the

745

cc

Atlas

model.

It

is mainly

the

cycle

parts

of these

latter

models

which

differ.

Ordering spare parts

When wishing

to

purchase

spare

parts

for

the

Norton

Commando

it

is

best

to

deal

direct

with

an

accredited

Norton-

Villiers agent. Parts

cannot

be

obtained

direct

from

Norton-

Villiers Limited; all orders

must

be

routed

through

an

approved

agent, even

if

the

agent

does

not

hold

the

parts

required

in

stock.

When ordering parts, always

quote

the

frame

and

engine

numbers

in full,

without

omitting

any

prefixes

or

suffixes.

It

is

also advisable

to

include

note

of

the

colour

scheme

of

the

machine

if

the

parts

ordered

are

required

to

match

in.

The

engine

number

is

stamped

on

the

left

hand

side

of

the

crankcase

immediately

below

the

base

of

the

cylinder

barrel.

The

frame

number

is

stamped

on

an

identification

plate

rivetted

to

the

steeri

ng

head.

Frame

number

location

Always

fit

parts

of

genuine Norton-Villiers

manufacture.

Pattem

parts

may

be available sometimes

at

lower

cost,

but

they

do

not

necessarily

make a satisfactory

replacement

for

the

originals.

There

are cases where

reduced

life

or

sudden

failure

has occurred,

to

the

overall

detriment

of

performance

and

perhaps

ri

der

safety.

'

Some

of

the

more

expendable

parts

such as spark plugs,

bulbs, tyres, oils

and

greases

etc.,

can

be

obtained

from

accessory

shops

and

motor

factors,

who

have

convenient

opening

hours,

charge

lower

prices

and

can

often

be

found

not

far

from

home.

It

is also possible

to

obtain

parts

on

a Mail

Order

basis

from

a

number

of

specialists

who

advertise regularly in

the

motor

cycle

magazines.

Engine

number

location

Routine maintenance

Periodic routine

maintenance

is a continuous

process

that

commences

immediately

the

machine

is

used.

It

must

be carried

out

at

specified mileage recordings

or

on

a calendar basis if

the

machine

is

not

used

frequently,

whichever falls

soonest.

Main-

tenance

should

be regarded as

an

insurance policy,

to

help

keep

the

machine in

the

peak

of

condition

and

to

ensure

long,

trouble-free

service. It has

the

additional

benefit

of

giving early

waming

of

any faults

that

may

develop

and

will

act

as a regular

safety

check,

to

the

obvious advantage

of

both

rider

and

machine alike.

The

various

maintenance

tasks are described

under

their

respective mileage

and

calendar

headings. Accompanying diagrams

are

provided, where necessary.

It

should

be

remembered

that

the

interval betvveen

the

various

maintenance

tasks serves

only

as a guide. As

the

machine gets

older

or

is

used

under

particularly

adverse

conditions,

it

would

be

advisable

to

reduce

the

period

betvveen

each

check.

Some

of

the

tasks are

described

in detail, where

they

are

not

mentioned

fully

as a routine

maintenance

item

in

the

text.

If

a

specific

item

is

mentioned

but

not

described in detail,

it

will be

covered

fully

in

the

appropriate

Chapter.

No special

tools

are

required

for

the

normal

routine

maintenance

tasks.

The

tools

contained

in

the

kit

supplied

with

every

new

machine will prove

adequate

for

each

task

or

if

they

are

not

available,

the

tools

found

in

the

average

household.

Weekly

or

every

250

miles

Check

oil

tank

level

and

replenish if necessary

with

engine oil

of

the

recommended

grade.

Grease brake pedal

pivot

and

cable, oil all

other

exposed

control

cables

and

joints.

Check

the

battery

electrolyte

level, chain

adjustments

and

tyre

pressures.

Monthly

or

every

1000

miles

Complete

the

maintenance

tasks listed

under

the

preceding

vveekly heading,

then

the

fOllowing additional items:

Check

and,

if

necessary,

adjust

both

brakes (disc brake

is

self-adjusting). Make

sure

disc brake fluid level is

correct

in

reservoir. Examine

the

disc

brake

pads

for

vvear.

Check primary chaincase oil level

and

top

up if necessary.

Check

nuts

and

bolts

for

tightness.

Three

monthly

or

every

2500

miles

Complete

all

the

checks listed

under

the

vveekly

and

monthly

headings,

then

the

following

items:

Drain

the

oil

tank

whilst

the

oil

is

warm

and

remove

and

clean

the

filters

before

refilling with

new

oil

of

the

correct

viscosity.

Remove

and

replace

the

oil filter

element

(fitted

to

all

models,

1972

onwards).

Check

the

gearbox

oil level

and

top

up if necessary.

Remove

and

clean

both

spark

plugs

and

reset

the

gaps.

Check

the

ignition

timing

after

adjusting

the

contact

breaker

gaps. It

is

preferable

to

use a

stroboscope

for

this

check.

Remove

and

lubricate

the

final drive

chain;

change

the

primary

chaincase oil.

Check

the

primary chain

adjustment

and

the

clutch

adjustment.

Finally,

check

the

Isolastic engine mountings

for

excess play.

Six

monthly

or

every

5000

miles

Again,

complete

all

the

maintenance tasks listed previously,

then

complete

the

following additional tasks:

Change

the

gearbox

oil,

and

also

the

oil in

the

front

forks.

Check

and

adjust

the

camshaft

chain.

Clean

the

contact

breaker

points

and

lubricate

the

contact

breaker

cam

and

the

auto-advance unit.

Grease

the

brake

operating

arm

pivots (grease sparingly

to

prevent grease reaching

the

brake linings).

Check

and,

if

necessary, adjust

the

valve clearances.

Fit a new

air

filter

element;

dismantle

and

clean

both

carburettors.

Check

that

they

are

synchronised

correctly.

Check

the

swinging

arm

bushes

for

play

and

fill

the

pivot

housing with oil.

Yearly

or

every

10,000

miles

After

completing

the

vveekly,

monthly,

three-monthly

and

six-monthly taSks,

continue

with

the

following additional items:

Remove

and

repack

the

wheel bearings

with

grease,

not

omitting

the

bearing in

the

centre

of

the

final drive

sprocket.

Check

the

primary

and

secondary

chains

and

sprockets

for

vvear,

al~o

both

carburettors.

If performance has fallen

off,

decarbonise

the

engine

and

regrind

the

valves.

It

should

be

noted

that

no

special

mention

has been made

relating

to

the

lighting

equipment,

horn

and

speedometer,

which

must

be in

good

working

order

if

the

statutory

requirements

of

the

UK

are

to

be

met.

RegUlations also

apply

to

the

minimum

depth

of

tyre

tread

and

the

overall

condition

of

the

tyres.

It

is

assumed

that

every

owner/rider

will keep a

watchful

eye

on

these additional

points,

especially since

they

have a

direct

bearing

on

rider

safety.

Remember

there

is

no

stage

at

any

point

in

the

life

of

the

machine

when a routine

maintenance

task

can be

ignored

or

safety

checks

neglected.

8

RM.1.

Lubrication

points

1 Engine oil

tank

2

Gearbox

3 Primary chaincase

4

Control

cables

5 Telescopic

fork

6 Swinging

arm

7 Wheel

hubs

8 Brake

cams

9 Brake pedal

pivot

Footnote:

o

o

Denotes lube

points

on

left

side

of

motorcycle

Recommended lubricants

Specification

Engine

and

primary

chaincase

20W/50

Gearbox

90

EP

Swinging

arm

bushes

140

EP

Hubs

and

cycle

parts

Front

forks

10W/30

Rear

chain

Hydraulic disc

brake

Denotes lube

points

on

right

side

of

motorcycle

Castrol

Product

Castrol GTX

Castrol Hypoy

Castrol Hi·Press

Castrol

LM

Grease

Castrolite

Castrol

Graphited

Grease

Castrol Girling Universal Brake

and

Clutch

Fluid

Routine maintenance and capacities data

Oil

tank

Gearbox

Primary chaincase

Front

forks

Contact

breaker

gap

Spark

plug gap

Tappet

clearances (engine

cold)

5 Imp pints (6

US

pints/2.8

litres)

0.75

Imp

pints

(0.9

US

pints/OA2Iitres)

7

fl

oz

(200 ee)

5

fl

oz

(150

ee)

0.014

·0.016

in

(0.35 -0.04

mm)

0.023 -0.028

in

(0.59 -0.72

mm)

0.006

in (0.15

mm)

inlet

(Commando)

0.008

in (0.20

mm)

inlet

(Combat)

0.008

in

(0.20

mm)

exhaust

(Commando)

0.010

in (0.25

mm)

exhaust

(Combat)

Safety

first!

Professional

motor

mechanics

are

trained

in

safe

working

procedures.

However

enthusiastic

you

may

be

about

getting

on

with

the

job

in

hand,

do

take

the

time

to

ensure

that

your

safety

is

not

put

at

risk. A

moment's

lack

of

attention

can

result

in

an

accident,

as can

failure

to

observe

certain

elementary

precautions.

There

will

always

be

new

ways

of

having

accidents,

and

the

following

points

do

not

pretend

to

be a comprehensive

list

of

all

dangers;

they

are

intended

rather

to

make

you

aware

of

the

risks

and

to

encourage a safety-conscious

approach

to

all

work

you

carry

out

on

your

vehicle.

Essential

DOs

and

DON'Ts

DON'T

start

the

engine

without

first

ascertaining

that

the

transmission

is

in

neutral.

DON'T

suddenly

remove

the

filler

cap

from a hot

cooling

system -cover

it

with a cloth

and

release

the

pressure

gradually

first,

or

you

may

get

scalded

by

escaping

coolant.

DON'T

attempt

to

drain

oil

until

you

are sure

it

has

cooled

sufficiently

to

avoid

scalding

you.

DON'T

grasp

any

part

of

the

engine,

exhaust

or

silencer

without

first

ascertaining

that

it

is

sufficiently

cool

to

avoid

burning

you.

DON'T

allow

brake

fluid

or

antifreeze

to

contact

the

machine's

paintwork

or

plastic

components.

DON'T

syphon

toxic

liquids

such

as fuel,

brake

fluid

or

antifreeze

by

mouth,

or

allow

them

to

remain

on

your

skin.

DON'T

inhale

dust -it

may

be

injurious

to

health

(see

Asbestos

heading).

DON'T

allow

any

spilt

oil

or

grease

to

remain

on

the

floor

-

wipe

it

up

straight

away,

before

someone

slips

on

it.

DON'T

use

ill-fitting

spanners

or

other

tools

which

may

slip

and

cause

injury.

DON'T

attempt

to

lift a heavy

component

which

may

be

beyond

your

capability -get

assistance.

DON'T

rush

to

finish

a'job,

or

take

unverified

short

cuts.

DON'T

allow

children

or

animals

in

or

around

an

unattended

vehicle.

DON'T

inflate a tyre

to a pressure

above

the

recommended

maximum.

Apart

from

overstressing

the

carcase

and

wheel

rim,

in

extreme

cases

the

tyre

may

blow

off

forcibly.

DO

ensure

that

the

machine

is

supported

securely

at

all

times.

This

is

especially

important

when

the

machine

is

blocked

up

to

aid

wheel

or

fork

removal.

DO

take

care

when

attempting

to

slacken a stubborn

nut

or

bolt.

It

is

generally

better

to

pull

on

a spanner,

rather

than

push,

so

that

if

slippage

occurs

you

fall

away

from

the

machine

rather

than

on

to

it.

DO

wear

eye

protection

when

using

power

tools

such

as

drill,

sander,

bench

grinqer

etc.

DO

use a

barrier

cream

on

your

hands

prior

to

undertaking

dirty

jobs -it

will

protect

your

skin

from

infection

as

well

as

making

the

dirt

easier

to

remove

afterwards;

but

make

sure

your

hands

aren't

left

slippery.

Note

that

long-term

contact

with

used

engine

oil

can

be a

health

hazard.

DO

keep

loose

clothing

(cuffs,

tie

etc)

and

long

hair

well

out

of

the

way

of

moving

mechanical

parts.

DO

remove

rings,

wristwatch

etc,

before

working

on

the

vehicle

-

especially

the

electrical

system.

DO

keep

your

work

area

tidy -it

is

only

too

easy

to

fall

over

articles

left

lying

around.

DO

exercise

caution

when

compressing

springs

for

removal

or

installation.

Ensure

that

the

tension

is

applied

and

released

in

a

controlled

manner,

using

suitable

tools

which

preclude

the

possibility

of

the

spring

escaping

violently.

DO

ensure

that

any

lifting

tackle

used

has

a safe

working

load

rating

adequate

for

the

job.

DO

get

someone

to

check

periodically

that

all

is

well,

when

working

alone

on

the

vehicle,

DO

carry

out

work

in a logical

sequence

and

check

that

everything

is

correctly

assembled

and

tightened

afterwards.

DO

remember

that

your

vehicle's

safety

affects

that

of

yourself

and

others.

If

in

doubt

on

any

point,

get

specialist

advice.

IF.

in

spite

of

following

these

precautions,

you

are

unfortunate

enough

to

injure

yourself,

seek

medical

attention

as

soon

as

possible.

Asbestos

Certain

friction,

insulating,

sealing,

and

other

products

-

such

as

brake

linings,

clutch

linings,

gaskets,

etc -contain

asbestos.

Extreme

care

must

be

taken

to

avoid

inhalation

of

dust

from

such

products

since

it

is

hazardous

to

health.

If

in

doubt,

assume

that

they

do

contain

asbestos.

Fire

Remember

at

all

times

that

petrol

(gasoline)

is

highly

flammable.

Never

smoke,

or

have any

kind

of

naked

flame

around,

when

working

on

the

vehicle.

But

the

risk

does

not

end

there

- a

spark

caused

by

an

electrical

short-circuit,

by

two

metal

surfaces

contacting

each

other,

by

careless

use

of

tools

..

or

even

by

static

electricity

built

up

in

your

body

under

certain

conditions,

can

ignite

petrol

VapOIJr,

which

in a confined

space

is

highly

explosive.

Always

disconnect

the

battery

earth

(ground)

terminal

before

working

on

any

part

of

the

fuel

or

electrical

system,

and

never

risk

spilling

fuel

on

to a hot

engine

or

exhaust.

It

is

recommended

that

a fire

extinguisher

of a type

suitable

for

fuel

and

electrical

fires

is

kept

handy

in

the

garage

or

workplace

at

all

times.

Never

try

to

extinguish a fuel

or

electrical

fire

with

water.

Note:

Any

reference

to a 'torch'

appearing

in

this

manual

should

always

be

taken

to

mean a hand-held

battery-operated

electric

lamp

or

flashlight.

It

does

not

mean a welding/gas

torch

or

blowlamp.

Fumes

Certain

fumes

are

highly

toxic

and

can

quickly

cause

unconsciousness

and

even

death

if

inhaled

to

any

extent.

Petrol

(gasoline)

vapour

comes

into

this

category,

as

do

the

vapours

from

certain

solvents

such

as

trichloroethylene.

Any

draining

or

pouring

of

such

volatile

fiuids

should

be

done

in a well

ventilated

area.

When

using

cleaning

fluids

and

solvents,

read

the

instruc-

tions

carefully.

Never

use

materials

from

unmarked

containers-

they

may

give

off

poisonous

vapours.

Never

run

the

'engine

of a motor

vehicle

in

an

enclosed

space

such

as a

garage.

Exhaust

fumes

contain

carbon

mon-

oxide

which

is

extremely

poisonous;

if

you

need

to

run

the

engine,

always

do

so

in

the

open

air

or

at

least

have

the

rear

of

.

the

vehicle

outside

the

workplace.

The

battery

Never

cause

a spark,

or

allow a naked

light,

near

the

vehicle's

battery.

It

will

normally

be

giving

off a certain

amount

of

hydrogen

gas,

which

is

highly

explosive.

Always

disconnect

the

battery

earth

(ground)

terminal

before

working

on

the

fuel

or

electrical

systems.

If

possible,

loosen

the

filler

plugs

or

cover

when

charging

the

battery

from

an

external

source.

Do

not

charge

at

an

excessive

rate

or

the

battery

may

burst.

Take

care

when

topping

up

and

when

carrying

the

battery.

The

acid

electrolyte,

even

when

diluted,

is

very

corrosive

and

should

not

be

allowed

to

contact

the

eyes

or

skin.

If

you

ever

need

to

prepare

electrolyte

yourself,

always

add

the· acid

slowly

to

the

water,

and

never

the

other

way

round.

Protect

against

splashes

by

wearing

rubber

gloves

and

goggles.

Mains electricity

and

electrical

equipment

When

using

an

electric

power

tool,

inspection

light

etc,

always

ensure

that

the

appliance

is

correctly

connected

to

its

plug

and

that,

where

necessary,

it

is

properly

earthed

(grounded).

Do

not

use

such

appliances

in

damp

conditions

and, again,

beware

of

creating a spark

or

applying

excessive

heat

in

the

vicinity

of

fuel

or

fuel

vapour.

Also

ensure

that

the

appliances

meet

the

relevant

national

safety

standards.

Ignition

HT

voltage

A severe

electric

shock

can

result

from

touching

certain

parts

of

the

ignition

system,

such

as

the

HT

leads,

when

the

engine

is

running

or

being

cranked,

particularly

if

components

are

damp

or

the

insulation

is

defective.

Where

an

electronic

ignition

system

is

fitted,

the

HT

voltage

is

much

higher

and

could

prove

fatal.

English/American

terminology

Because

this

book

has

been

written

in England,

British

English

component

names,

phrases and

spellings

have been used

throughout.

American

English usage is

quite

often

different

and

whereas

normally

no

confusion

should

occur, a list

of

equivalent

terminology

is

given

below.

English

American

English American

Air

filter

Air

cleaner

Number

plate License

plate

Alignment

(headlamp)

Aim

Output

or

layshaft

Countershaft

Allen

screw/key

Socket

screw/wrench

Panniers Side cases

Anticlockwise

Counterclockwise

Paraffin Kerosene

Bottom/top

gear

Low/high

gear

Petrol Gasoline

Bottom/top

yoke

Bottom/top

triple

clamp

Petrol/fuel

tank

Gas

tank

Bush

Bushing

Pinking Pinging

Carburettor

Carburetor

Rear suspension

unit

Rear

shock

absorber

Catch

Latch

Rocker cover Valve

cover

Circlip

Snap

ring

Selector

Shifter

Clutch

drum

Clutch

housing

Self-locking

pliers

Vise-grips

Dip

switch

Dimmer

switch

Side

or

parking

lamp

Parking

or

auxiliary

light

Disulphide

Disulfide

Side

or

prop

stand

Kick

stand

Dynamo

DC

generator

Silencer

Muffler

Earth

Ground

Spanner

Wrench

End

float

End

play

Split

pin

Cotter

pin

Engineer's blue

Machinist's

dye

Stanchion

Tube

Exhaust pipe

Header

Sulphuric

Sulfuric

Fault

diagnosis

Trouble

shooting

Sump

Oil pan

Float

chamber

Float

bowl

Swingin~

arm

Swingarm

Footrest

Footpeg

Tab

washer

Lock

washer

Fuel/petrol

tap

Petcock

Top

box

Trunk

Gaiter

Boot

Torch

Flashlight

Gearbox

Transmission

Two/four

stroke

Two/four

cycle

Gearchange

Shift

Tyre

Tire

Gudgeon

pin

Wrist/piston

pin

Valve

collar

Valve

retainer

Indicator

Turn

signal

Valve

collets

Valve

cotters

Inlet

Intake

Vice

Vise

I

nput

shaft

or

mainshaft

Mainshaft

Wheel

spindle

Axle

Kickstart

Kickstarter

White

spirit

Stoddard

solvent

Lower

leg

Slider

Windscreen

Windshield

Mudguard

Fender

Chapter 1

Engine

Contents

General

description

..............

.

Operations

with

engine in

frame

Operations

with

engine removed .. .

Method

of

engine removal

........

.

Dismantling

the

engine - removing

the

petrol

tank

Dismantling

the

engine - removing

the

cylinder

head

...

Dismantling

the

engine - removing

the

cylinder

barrels

and

pistons

........................

'"

...

'"

.. .

Dismantling

the

engine

- removing

the

alternator,

clutch

and

primary

chaincase

.....................

'"

...

'"

Dismantling

the

engine·

removing

the

crankcase

assembly

from

the

frame

... ... ... ... ... ... ...

'"

...

'"

...

Dismantling

the

engine

- removing

the

contact

breaker

and

auto-advance

assembly...

... ...

'"

...

'"

...

Dismantling

the

engine - removing

the

timing

cover, oil

pump

and

timing

chain

............

'"

........

.

Dismantling

the

engine - removing

the

crankshaft

pinion

and

separating

the

crankcases

......

'"

...

'"

.. .

Examination

and

renovation - general

...

'"

........

.

Crankshaft, big

end

and

engine bearings -

examination

and

renovation .,

...................

'"

.....

.

Timing

pinions,

timing

chain

and

chain

tensioner-

examination

and

renovation

..............

.

Timing

cover

oil seals -examination

and

renewal

Cylinder barrel -

examination

and

renovation

Specifications

Engine

Type

...........

.

Cylinder

head

Valve

seat

angles ...
Cylinder barrel
Bore

750

cc

850

cc

Stroke

750

cc

and

850

cc

Capacity (actual)

750cc
850

cc

Compression

ratio

Standard

750

cc

...

750

cc

Combat

850

cc

Bhp

Standard

750

cc

...

750

cc

Combat

engine

850

cc

.. ,

.....

, ...

1

2

3

4

5

6

7

8

9

10

11

12
13

14

15
16

17

Pistons, piston rings

and

small ends -

examination

and

renovation

........ , '"

...

'"

........

, ... ... ...

18

Valves, valve springs

and

valve guides -

examination

and

renovation ...

'"

...

'"

...

'" '"

'"

.......

,.

19

Cylinder

head -examination

and

renovation

20

Rocker

arms

and

rocker spindles -

examination

and

renovation ...

'"

...

'"

... ... ... ... ... ... ...

21

Camshaft

and

push rods -

examination

and

renovation

22

Engine reassembly - general ...

'"

... ... ... ... ... ...

23

Engine reassembly - rebuilding

the

crankshaft

assembly...

24

Engine reassembly - refitting

the

connecting

rods ...

25

Engine reassembly - reassembling

the

crankcases .. ,

26

Engine reassembly -

completing

reassembly

of

the

timing

side

.......

,.

'"

...

'"

... ... ... ...

27

Refitting

the

pistons

and

piston rings

28

Replacing

the

crankcase assembly in

the

frame

29

Engine reassembly - refitting

the

cylinder

barrel

30

Engine reassembly - reassembling

the

cylinder

head

31

Engine reassembly - refitting

the

cylinder

head

32

Engine reassembly - reassembling

the

primary

transmission ...

33

Engine reassembly -

completion

'"

... ... ...

34

Checking

and

resetting

the

valve clearances

35

Starting

and

running

the

rebuilt

engine

36

Increasing engine

performance

37

Fault

diagnosis

'"

'"

...

'"

...

'"

...

38

Twin

cylinder

four

stroke,

with

pushrod

operated

overhead

valves

Aluminium

alloy (RR 53B)

450 inlet

and

exhaust

Cast iron

73

mm

(2.875

in)

77

mm

(3.04 in)

89

mm

(3.503 in)

745

cc

828

cc

9:

1

10:

1

8.5:

1

60@6800rpm
65@6500rpm
60@5900rpm

12

Pistons

Diameter

at

bottom

of

skirt

Piston rings

Number
End

gaps

Valves

Material

Head diameter

Stem diameter

Valve sprihgs

Number

Free length

Valve guides

Internal diameter
External diameter

Heat resisting washer

Material

Thickness

........

.

Valve

timing

(measured

at

0.013

in

(0.3302

mm)

cam

lift!

Inlet

opens

BTDC

•..

Inlet

closes

ABDC

...

Exhaust opens

BBDC

Exhaust closes A

TDC

Ignition

timing

Main

bearings
Make
Type

Drive side ...
Timing

side

Size

Cylinder

head gaskets

(750

cc

only)

Norton

Villiers

part

number

Type

..•.....•...

Thickness (inches)

Use

.••••..•••••

850

cc models

use

Part

No

065051

Torque

wrench settings

Cylinder

head nuts

and

bolts

(3/8

in)

Cylinder

head bolts (5116

in)

•.......•

Cylinder

base

nuts

(3/8

in)

and

cylinder

through

bolts

(850

cc

only)

Cylinder

base

nuts (5116

in)

Connecting

rod

nuts

Crankshaft nuts

........

.

Engine

mounting

bolts

..

.

Rotor

nut

(alternator)

Alternator

stud

nuts ...

Clutch

centre

nut

Gearbox

sprocket

nut

Rear suspension

unit

mounting

nuts ...

Disc brake caliper

fork

leg

mounting

bolts ...

Disc brake caliper

end

plug

Oil

pressure release valve ... ...

...

... ... . ..

Chapter 1/Engine

2.8713 -2.8703

in

(72.931

-72.906

mm) -750

cc

Two

compression, one

oil

control

per

piston

0.010 -0.012

in

(0.245

- 0.305

mm) -top

ring (chrome)

0.008 -0.012

in

(0.203 -

0.305

mm) -2nd

ring

(taper)

EN52 -inlet
KE965

- exhaust

1.500

in

(38.1

mm)

inlet -750

cc

1.312

in

(33.325

mm)

exhaust -

750

cc

0.3115 -0.3105

in

(7.912

-7.886

mm)

inlet

and exhaust valves

-750cc

Two

per valve

1.618

in

(41.097

mm) -outer

spring

1.482

in

(37.642

mm) -inner

spring

0.3145 -0.3135

in

(7.988 - 7.962

mm)

0.5015 -0.50

in

(12.738

-12.725

mm)

Tufnol

ASP

0.062

in

(1.574

mm)

Standard

50

0

74

0

82

0

42

0

750

cc engines

28°

fully

advanced

FAG

NJ306E

Ransome & Maries

6MRJA30

Combat

59

0

8go
88

0

60

0

Existing

bearings

must

be

replaced

with

either

of

these types

Single

lipped

roller

(pre-1972)

Special

roller

(single

lipped)

1972

onwards

Single

row

ball (pre-1972)

Special

roller

(single lipped)

1972

onwards

30

mm x 72

mm x 19

mm

(all)

063844

064071

064072

Eyeletted Copper

Alloy

0.030

0.040

0.080

750cc

750

750

High octane Reduced Discontinued

fuel

compression

used

for

low

ratio

octane fuel

only

ft

Ib

>

Kgm

30

4.15

20

2.75

25

3.45

20

2.75

25

3.45

25

3.45

25

3.45

80

11.06

15

2.07

70

9.68

80

11.06

30

4.15

30

4.15

26

3.60

25

3.45

Chapter 1/Engine

13

General

description

The engine

fitted

to

the

Norton

750

cc

and

850

cc

Commando

models

is

a vertical

twin

cylinder,

in which

both

pistons are

arranged

to

rise

and

fall

in

unison.

The

engine

is

mounted

in an

inclined

position,

using

what

is

known as

the

Isolastic suspension

system

to

damp

out

the

unwanted

effects

of

high

frequency

engine vibration

associated

with this

type

of

engine

design. An

overhead

valve

layout

is

used, which

is

actuated

by

push

rods

that

pass

through

cast-in

tunnels

at

the

front

of

the

cylinder

barrel.

Lubrication

is

effected

on

the

dry

sump

principle,

in which

oil

is

fed

by

gravity

to

a gear-type

pump

and

distributed

to

the

various parts of

the

engine. A separate

scavenge

pump

which

forms

part

of

the

oil

pump

assembly ensures oil

which

. drains

back

into

the

crankcase

is

returned

to

the

oil

tank.

The

crankshaft

assembly comprises a wide

centre

flywheel,

with

two

outer

bob

weights

one

on each side.

The

big

end

bearings are

of

the

shell

type,

fitted

to

split,

light alloy

connecting

rods.

The

cylinder

barrel

is

of

cast

iron

and

the

cylinder

head

of

aluminium

alloy,

both

taking

the

form

of

monobloc

castings.

The

Combat

engine

is

normally

identified

by

the

additional

matt

black

finish given

to

the

exterior

cooling surfaces of

the

cylinder

barrel.

Ignition is

provided

by

twin coils

and a twin

contact

breaker

assembly driven

off

the

end

of

the

camshaft,

the

latter

incorporating

an

automatic

advance

and

retard

nut.

Twin

carburettors

are

specified,

fitted

with a large

capacity

air

cleaner.

The

engine has

twin

exhaust

pipes

and

silencers

of

the

downswept

type

with

special

rubber

mountings.

Only

the

'5'

model has an

upswept

system

on

the

left

hand

side

of

the

machine.

The lubrication

system

is

protected

by

a gauze

filter

within

the

oil

tank

and a magnetic

drain plug in

the

crankcase

and

a

pressure relief valve.

Post-1972

models have

an

additional

car-

type

oil filter, with a renewable cartridge

element,

fitted

within

the

rear engine

plates,

in close

proximity

to

the

rear wheel.

Provided

the

machine

is

maintained

regularly in

an

intelligent

manner,

the

lubrication

system

is

unlikely

to

give

trouble

during

normal

service.

2

Operations

with engine in

frame

It

is

not

necessary

to

remove

the

engine

from

the

frame

unless

the

crankshaft

assembly,

the

big

ends

or

the

camshaft

require

attention.

Most

operations

can be

accomplished

with

the

engine in

the

frame,

such

as:

a) Removal

and

replacement

of

the

cylinder

head.

b) Removal

and

replacement

of

the

cylinder

barrel

and

pistons.

c) Removal

and

replacement

of

the

clutch

and

primary

drive.

d) Removal

of

the

timing

sprockets

and

oil

pump.

e) Removal of

the

contact

breaker

and

automatic

advance

assembly.

2 When several

operations

have

to

be

undertaken

simultaneously,

such

as

during

an

extensive

rebuild

or

overhaul,

it

is

often

advantageous

to

remove

the

engine

from

the

frame

after

some

preliminary dismantling. This will give

the

advantage

of

better

access

and

more

working

space,

especially if

the

engine is

attached

to a bench-mounted

stand.

3

Operations

with

the

engine removed

1 Removal

and

replacement

of

the

main bearings.

2 Removal

and

replacement

of

the

crankshaft

assembly.

3 Removal

and

replacement

of

the

camshaft.

4

Method

of

engine removal

The engine

is

heavy, even

for

two

mechanics.

In

consequence,

it is

preferable

to

partially

strip

the

engine

before

it

is

released

from

the

frame,

in

order

to

shed

some

of

the

heavier

components

such

as

the

cast

iron

cylinder

barrel

and

to

give greater

freedom

of

movement.

2

The

engine

and

gearbox

are

separate

units which means

that

the

engine

can

be removed

without

disturbing

the

gearbox

apart

from

the

need

to

dismantle

the

primary

transmission.

5 Dismantling

the

engine - removing

the

petrol

tank

Place

the

machine

on

the

centre

stand

and

ensure

that

it

is

standing

firmly

on

level

ground.

2

Turn

off

both

petrol

taps

and

disconnect

the

petrol

pipes

by

unscrewing

the

unions where

they

join

the

base

of

each

tap.

3

Remove

the

dual

seat.

This is released

by

unscrewing

the

two

large

diameter

milled knobs

at

the

top

of

each

rear suspension

unit.

The

seat

will lift

straight

up

in

the

case

of

the

Fastback

models;

on

other

models

it

is

necessary

to

lift upwards,

then

pull

towards

the

rear

of

the

machine.

4

To

obviate

the

risk

of

fire, remove

the

fuse

from

its

holder

in

the

battery

negative lead. This will isolate

the

electrical

system.

5

The

petrol

tank

is

secured

at

the

front

by

self-locking

nuts

attached

to

studs

which

protrude

from

the

underside

of

the

tank.

Remove

the

nuts

and any

rubber

washers

below

the

tank

mounting

lugs.

5

The

rear

of

the

tank

will

be

secured

by

either a rubber

strap

or

a cross

strap

beneath

the

main

tube

of

the

frame

which

is

held

by

nuts

and

washers.

The

method

of

mounting

used will

depend

on

the

model. When

the

front

and

rear fixings have been

removed,

the

tank

can be lifted away

from

the

frame.

6 Since

there

is

no

necessity

to

drain

the

tank

prior

to

these

operations,

it

can

represent

a dangerous fire

hazard.

Make

sure

it

is

placed

well away

from

the

machine

and

any

naked

flames

or

other

sources where

involuntary

ignition

may

occur.

7

Note

the

position

of

the

rUbber

support

pads

over

the

main

frame

tube

so

that

they

are

located

accurately

when

the

tank

is

eventually

replaced.

6 Dismantling

the

engine·

removing

the

cylinder

head

Most

models

are

fitted

with a

downswept

exhaust

system.

This

is

removed

by

bending

back

the

tab

washer

on

each

exhaust

locking ring

and

then

unscrewing

each

ring

to

free

the

exhaust

pipe

from

the

cylinder

head.

Norton

Villiers service tool

063968

is

recommended

for

this

purpose

as

the

rings are locked

tight.

If

the

service

tool

is

not

available,

the

rings can be

slackened

by

careful application

of a flat

nosed

punch

and

hammer.

The

850

cc

models

have a balance

pipe,

the

-clips

of

which

must

be

slackened.

2

To

release

the

silencers,

unscrew

the

nuts

which secure

the

mounting

plates

to

the

two

rubber

mountings.

The

exhaust

pipes

and

silencers

can

then

be

lifted

away

as a

complete

unit.

3 A

somewhat

similar

procedure

is

recommended

for

the

upswept

exhaust

system

fitted'

to

the

'5'

models.

In

this

instance,

the

silencer has

only

one

point

of

attachment,

on

a

bracket

adjacent

to

the

rear suspension

unit.

4

Note

there

is a

copper/asbestos

sealing ring in 'each

exhaust

port,

which

should

be removed

and

discarded.

It

is

customary

to

fit

new

replacements when

the

exhaust

system

is eventually

refitted

in

order

to

preserve a

leaktight

joint.

5

Remove

both

carburettors

complete

with spacers

by

unscrew-

ing

the

four

socket

screws

which

retain

the

assembly

to

the'

cylinder

head.

Access is made easier

by

using a

short

socket

key

in

order

to

provide clearance

with

the

frame

tube.

Disengage

the

air

cleaner

hoses

from

each

carburettor

intake

and

lift

the

carburettors

away.

If desired,

the

carburettors

can

be

separated

by

disconnecting

the

balance

pipe

which joins

them

and

by

removing

each

carburettor

top,

retained

by

two

crosshead screws.

This will

enable

the

slide

and

needle assembly,

comple~h

control

cables,

to

be lifted

out

of

each

mixing

chamber.

6 Whichever

method

is

used

for

the

removal of

the

carburettor,

5.2

Disconnect petrol pipes

at

petrol

tap

unions

6.2

Swinging

arm

prevents removal

of

mounting

bolt

...

6.5

.Remove

carburettors

complete

with spacers

-----

6.1 Use a

'C'

spanner

to

slacken

exhaust

locking rings

6.2a

..•

disconnect

at

rubber

mountings

as

alternative

6.6

Separate

air

cleaner

after

removing

two

retaining

bolts

6.7

Twin coil assembly bolts

to

mounting

on

frame

tube

...

6.8

Head steady assembly

comprises

two

short

plates

and

...

6.12

Push rods

must

be

fed

into

cylinder

head

to

aid

removal

6.7a

.•. place

out

of

harms way;

no

necessity

to

detach

com-

pletely

6.8a ..• base plate

attached

to

head

by

socket

screws

7.1

Support

pistons as

they

emerge

from

bores

to

prevent

dam-

age

16

FIG.

1.1.

CYLINDER

BARREL

AND

CYLINDER

HEAD

1

Cylinder

barrel-

850

cc

models

2

Cylinder

barrel -750

cc

models

3

Cylinder

head

gasket

(eyeletted) -850

cc

models

4

Cylinder

head

gasket

(eyeletted) -750

cc

models

5

Cylinder

head -850

cc

models

6

Cylinder

head -750

cc

models

{3D

mm,

low

compression

-

marked

RHtJ

6a

Cylinder

head -750

cc

models

(32

mm,

high

compression

-

marked

RH6)

6b

Cylinder

head -750

cc

models

(32

mm,

low

compression

-

marked

RH5)

7

Rocker

cover

stud -front

8

Rocker

cover

stud -rear

9

Rocker

cover

dowel

10

Rockercover-

front 2 off

11

Rocker

cover

gasket -front 2 off

12

Rocker

cover

nut -front 4 off

13

Rocker

cover -rear

14

Rocker

cover

gasket -rear

15

Rocker

cover

stud

washer

16

Rocker

cover

stud

nut -rear

17

Cylinder

through

bolt

(850

cc

models

only) 4 off

18

Washer

for

through

bolt

(850

cc

models

only) 4 off

19

Cylinder

barrel

stud 2 off

20

Cylinder

head

stud 3 off

21

Cylinder

head

sleeve

nut 2 off

22

Cylinder

head

nut 2 off

23

Cylinder

head

nut

24

Cylinder

head

washer 2 off

25

Cylinder

head

bolt 4 off

26

Cylinder

head

bolt

(short)

27

Cylinder

head

washer 5 off

17

18

Chapter 1/Engine

ensure

the

parts

involved are

taped

out

of

harms

way.

They

are

very easily

damaged

if mishandled. Lift

away

the

air cleaner

assembly by

withdrawing

the

two

long bolts which

hold

the

case
together.
7

Unbolt

the

twin

ignition coil assembly

from

its

mounting

above

the

cylinder

head

and

disconnect

both

caps

from

the

spark

plugs.

The

coil assembly

need

not

be

removed

completely;

it

can be

tied

to

the

handlebars

so

that

it

does

not

impede

removal

of

the

cylinder

head.

Only

the

electrical

connections

from

the

coils

to

the

contact

breakers

need

be removed.

8 Remove

the

cylinder

head

steady.

This

takes

the

form

of

two

short

plates which

interconnect a plate

bolted

to

the

cylinder head

with

two

rubber

mountings,

one

on

each

side of

the

tube

below

the

main

frame

tube.

Remove

the

nuts

from

the

rubber

mountings

first in

order

to

prevent

the

mountings

from

rotating. When

the

two

mounting

plates have been removed,

remove also

the

head

steady

from

the

cylinder

head

by

with-

drawing

the

three

socket

screws which retain

it.

9 Remove

both

spark

plugs

and

remove

the

rocker

oil feed

pipes

from

both

sides of

the

cylinder

head

casting. Special care

is

needed

when

unscrewing

the

banjo

union

bolts

to

prevent

the

thin

copper

pipe

from

twisting

or

necking. Detach

the

copper

sealing washers

from

either

side

of

each

union

but

leave

the

feed

pipe

attached

to

the

timing

cover.

10 Slacken

and

remove nine of

the

cylinder

head

retaining

bolts, leaving

only

the

front

centre

bolt

in

position.

This

and

the

two

bolts,

one

on

either

side, are recessed

into

the

cylinder

head

and

will require a slim

socket

or

box

spanner

for

their

release.

Two

nuts

are

found

on

the

underside

of

the

cylinder

head,

at

the

front,

and

another

single

nut

on

the

underside,

at

the

rear.

The

four

remaining bolts are easily accessible

from

the

top

of

the

cylinder

head,

making a

total

of

ten

bolts.

850

cc

models

include

four

through

bolts in

the

cylinder

barrel.

11

When

the

front

cylinder

head

bolt

is

removed

last

of

all,

the

cylinder head will

tilt

a little against

the

spring

pressure

of

the

valve

which

is

open.

This will aid breaking

the

cylinder

head

joint.

12 Before

the

cylinder

head

can

be lifted

away,

it

is

necessary

to

feed

each

of

the

four

push

rods

into

the

cylinder

head

as

far

as

possible,

after

detaching

them

from

the

ends

of

the

rocker

arms.

This

can

be

accomplished

by

tilting

the

cylinder

head

towards

the

rear, whilst

holding

the

cylinder

head

with

one

hand

and

the

push rods

with

the

other.

Do

not

use

force

and

make

sure

the

push rods are

clear

of

the

cylinder

barrel

as

the

head

is being

removed. Failure

to

observe this

precaution

may

cause damage

to

the

light

alloy

pushrods,

necessitating

their

renewal.

13

The

cylinder

head

gasket will

adhere

to

either

the

cylinder

barrel

or

cylinder

head

and

should

not

be re·used unless

it

is

completely

undamaged.

7 Dismantling

the

engine·

removing

the

cylinder

barrel

and

pistons

1

The

c.ylinder barrel

is

retained

to

the

crankcase

by nine

studs

(and

four

through

bolts,

850

cc

models

only).

Remove

the

nine holding

down

nuts

(and

the

through

bolts,

850

cc

models)

and

ease

the

cylinder

barrel upwards,

taking

care

to

support

the

pistons as

they

emerge

from

the

cylinder

bores.

If

broken

piston

rings

or

other

piston

damage is

suspected,

it

is advisable

to

pad

the

mouth

of

the

crankcase with clean rag

immediately

the

cylinder barrel

is

raised

to

prevent

displaced

particles

from
falling in.
2 Remove

and

discard

the

circlips

from

each

piston,

then

remove

both

gudgeon pins, taking care

to

support

the

piston

and

connecting

rod

as

they

are

tapped

out

of

position.

If

the

pins

are a

tight

fit,

the

pistons

should

be

warmed

first

by

placing a

rag

soaked

in

hot

water

on

each

crown.

This will

expand

the

alloy
of

the

piston

and

release

the

grip

of

the

gudgeon pin boss. On

no

account

use

force,

or

the

light alloy

connecting

rods may

be

damaged

permanently.

3 Mark each

piston

INSIDE

the

skirt

to

ensure

it

is

replaced in

its original

position.

The

pistons are individually

marked

on

the

crown

to

this

effect,

but

the

marks

may

have

been

erased if

the

crown was badly

scratched

during

a previous

decoke.

Although

the

valve

cutaways

are

the

same

size in

the

crown

of

the

standard

ratio

pistons,

the

cutaway

for

the

exhaust

valve

is

positioned

much

nearer

to

the

edge. This makes

the

correct

location

of

the

pistons

vital.

8 Dismantling

the

engine - removing

the

alternator,

clutch

and

primary

chaincase

Remove

the

three

nuts

and

washers which secure

the

left

hand

footrest

and

rear brake pedal

to

the

light alloy

mounting

plate.

In

order

to

clear

the

primary

chaincase cover,

the

footrest

assembly can be left hanging

from

the

brake

cable;

the

alternative

is

to

remove

the

electrical

snap

connector

from

the

stop

lamp

switch

on

the

brake pedal

and

the

brake cable

from

the

rear

brake

operating

arm

so

that

the

complete

assembly

can

be

detached

and

lifted

away.

2 Place a large

tray

immediately

below

the

underside

of

the

chaincase jOint.

The

chaincase has

no

drain plug

and

in

consequence

the

full oil

content

will be released

immediately

the

two

halves are

separated.

3 Remove

the

centre

sleeve

nut

which retains

the

two

chaincase halves

together

and

rock

the

chaincase slightly

to

clear

the

two

locating dowels,

one

at

the

top

and

one

at

the

bottom.

Immediately

the

seal breaks,

the

oil

content

will

be

released

into

the

tray.

Remove

the

outer

cover

completely,

taking

care

that

the

rubber

seal

around

the

jointing

face

or

rear

half

of

the

chaincase is

not

displaced

and

damaged.

4 Place a

stout

metal

rod

through

the

small

end

of

both

connecting

rods

and

rotate

the

engine in an anticlockwise (drive)

position

until

the

rod rests across

the

crankcase

mouth.

This will

lock

the

engine in position

so

that

the

nut

of

the

alternator

rotor

can

be

slackened

and

removed. Use a

Yo

inch

Whitworth

socket

wrench

and

tum

in an anticlockwise

direction;

the

nut

has a

normal

right

hand

thread.

Do

not

misplace

the

washer

which

seats

below

the

nut.

5 Remove

the

alternator

stator

which

is

secured

by

three

nuts

and

washers. Draw

the

stator

assembly

off

the

studs,

after

detaching

the

lead wire

at

the

snap

connectors

in

the

vicinity

of

the

air

cleaner

housing.

The

lead wire will pull

through

the

small

rubber

grommet

in

the

centre

of

the

rear'chaincase.

6

The

alternator

rotor

is

keyed

onto

the

crankshaft

and

has a

parallel

fit.

In

consequence,

it

is

not

difficult

to

remove. Light

pressure

with

a pair of

tyre

levers

positioned

at

the

rear

of

the

rotor

should

provide

sufficient

leverage. Remove

the

rotor

key,

the

packing

collar

and

any

shims

on

the

crankshaft.

Detach

the

three

spacers

from

the

stator

mounting

sutds

and

place

them

in a

safe

position

for

reassembly.

7·

Whilst

the

engine

is

still

locked

in position, slacken

the

clutch

push

rod

adjuster

nut

in

the

centre

of

the

clutch

assembly

and

remove

both

the

adjuster

and

the

nut.

S

The

clutch

cannot

be

dismantled

without

the

compressor

which is necessary

for

the

diaphragm

spring.

Norton

Villiers

service

tool

060999

is

recommended

for

this

purpose.

DO

NOT

AlTEMPT

TO

DISMANTLE

THE

CLUTCH

WITHOUT

A

COMPRESSOR. IF

THE

TENSION

OF

THE

DIAPHRAGM

SPRING

IS

RELEASED

SUDDENLY

WITHOUT

PROTECTION,

SERIOUS

INJURY MAY

RESULT.

Do

not

unscrew

the

com-

pressor

from

the

diaphragm

or

the

latter

will

be

released

with

considerable

force.

9

Screw

the

centre

bolt

of

the

compressor

into

the

hole

previously

occupied

by

the

clutch

pushrod

adjuster

and

check

that

at

least

Yo

inch

of

the

bolt

has engaged

with

the

internal

thread.

Tum

the

out

in

a clockwise direction

until

the

diaphragm

spring

is

flat

and

free

to

rotate.

This will enable

the

retaining

circlip

to

be prised

from

its groove inside

the

periphery

of

the

clutch

body

by

a screwdriver

blade.

Lift

the

first

end

clear

of

the

groove,

then

peel

the

circlip

out

of

position.

The

compressor

and

diaphragm

can

then

be

lifted

away

together;

there

is

no

necessity

to

detach

the

compressor

until

after

the

clutch

is

reassembled. NEVER peel

out

the

circlip

without

first using a

compressor

to

compress

the

diaphragm.

10

Lift

out

the

clutch

plates, using

two

pieces

of

stout

wire

7.2

Never re·use circlips.

Old

circlips

must

be

discarded

7.2a

Warm

pistons

if

gudgeon pins are a

tight

fit

3.5

Alternator

stator

is

secured

by

three

nuts

8.5a

Lead

wire will pull

through

grommet

in

chaincase

8.6

Alternator

rotor

is

keyed

on

to

crankshaft

8.7

Slacken

push

rod

adjuster

whilst

engine

is

locked

20

Chapter

1/Engine

with

their

ends

bent

at

a right angle,

to

form a hook.

There

is

a

total

of eight,

four

plain

and

four

friction.

The

clutch

inner

drum

can

now

be

released

by

unscrewing

the

centre

nut.

To

prevent

the

clutch

from

turning,

select

top

gear

and

apply

the

rear

brake

by

pressing on

the

operating

arm. The

centre

nut

has a

right

hand

thread

and

should

be

removed,

after

bending

back

the

tab

washer,

complete

with

the

spring

washer

beneath

it.

Pullout

the

clutch

pushrod.

The

clutch

inner

drum

can

now

be

withdrawn.

11

The

triplex

primary

chain

is

of

the

endless

type

and

has

no

split

link

joint.

In

consequence

it

is

necessary

to

remove

the

clutch

outer

drum

with its integral

sprocket

and

the

engine

sprocket

in unison. The engine

sprocket

is

a keyed

taper

fit

on

the

end

of

the

crankshaft

and

it

is

essential

to

use a

sprocket

puller

to

achieve its release.

Norton

Villiers service

tool

060941

is

specified

for

this

purpose;

the

sprocket

is

tapped

to

accept

the

extractor

bolts. If

the

service

tool

is

not

available, a

two

or

three-

legged

sprocket

puller

can

be

used

with equal

effect.

Lift away

both

sprockets

together

with

the

triplex

chain.

Take special care

of

the

collar

and

spacers

fitted

over

the

gearbox

mainshaft,

behind

the

clutch,

since

they

determine

the

accurate

alignment

of

the

two

sprockets. Place

them

in a safe place until reassembly

commences.

There are spacers on

the

crankshaft,

behind

the

engine

sprocket

location,

and a Woodruff

key.

12

The

rear

half

of

the

chaincase

is

attached

to

the

left

hand

crankcase

by

three

screws

secured

by

tab

washers. Bend

back

the

tabs,

remove

the

screws,

and

pull away

the

rear chaincase.

Remove

the

spacers used on

the

centre

stud

which engages

with

the

sleeve

nut

that

retains

the

chaincase. The overall length of

the

spacers

must

be

correct

to

prevent

distortion

of

the

chaincase

when

the

sleeve

nut

is

tightened.

9 Dismantling

the

engine -

removing

the

crankcase assembly

from

the

frame

Unscrew

the

tachometer

cable

from

the

union

joint

in

front

of

the

ri'.Jht

hand

cylinder

barrel.

At

the

same

time

it

is

convenient

to

drain

the

oil

from

the

oil

tank

by

removing

the

drain plug,

or

in

the

case

of

the

early

models,

by

taking

out

the

larger oil

filter

union

which secures

the

main oil

feed

pipe

from

the

oil

tank.

It

will be necessary

to

detach

the

right

hand

sfde

cover

in

order

to

gain access

to

the

oil

tank.

This

task

is

best

accomplished whilst

the

oil

is

warm,

so

that

it

will

flow

more

freely.

2 Remove

the

rocker

feed

pipe

which is

joined

to

the

timing

cover

by

a banjo

union.

Take

care

not

to

lose

the

copper

sealing

\I\'8Shers.
3 Remove

the

gear

indicator

from

the

gearbox

end

cover

which

is

retained

by a setscrew

and

the

gear change lever,

secured

on

splines

by

a pinch

bolt.

Push

the

crankcase

breather

pipe clear

of

the

oil

tank.

Remove

the

right

hand

footrest

secured

by

two

nuts
and a bolt.
4 Place a large

capacity

tray

under

the

crankcase assembly

and

remove

the

oil pipe

junction'

block

from

the

right

hand

crankcase,

assuming

the

oil

tank

has

drained

completely.

Slacken

and

remove

the

hexagon

headed

drai n plug in

the

bottom

of

the

left

hand

crankcase. Early

models

(engine

numbers

prior

to

200000

and

those

of

850

cc

capacity)

have a large

diameter

plug

17/8 inch Whitworth)

which

houses a separate

filter. Later

750

cc

models have a

much

smaller

plug

of

the

magnetic

type

which

obviates

the

need

for

a filter. This

is

an additional

fitting

on

the

850

cc

engines. Allow all excess oil

to

drain off. Take

off

the

crankcase

breather

(early

models

only).

5

It

is necessary

to

remove

the

crankcase assembly

by

detaching

the

front

engine

mounting.

Remove

the

large

diameter

bolt

which

passes

through

the

centre

of

the

mounting,

taking

care

to

align

the

flats

on

the

head

so

that

the

bolt

will

clear

the

timing

case during removal.

The

bolt

has a small

head

to

facilitate

its removal in

this

fashion.

Prise back

the

gaiter

on

one

end

of

the

engine

mounting

so

that

the

spacer,

end

cap

and

shims

can

be

removed

to

ensure

freedom

of

movement

within

the

frame

lUgs.

6 Remove

the

two

nuts

from

the

right

hand

side

of

the

front

engine

mounting

sutds,

then

pullout

the

studs

complete

with

the

remaining nuts

from

the

left

hand

side of

the

mounting.

The

8.10

Release

inner

dru

m by unscrewing

retaining

nut

8.11 Puller is necessary

to

free engine

sprocket

8.11 a Chain is endless.

Take

off

sprockets

together

Chapter

1

IE

ngine

front

engine

mounting

can

now

be

withdrawn

from

the

crankcase

assembly

and

from

the

frame.

7

Remove

the

two

lower

rear

engine

bolts

which

pass

through

the

engine

plates

encasing

the

gearbox.

Before

the

lower

of

the

two

bolts

can

be

withdrawn,

it

will be

necessary

to

lift

the

front

of

the

crankcase

assembly

upwards

so

that

the

bolt

will

clear

the

lower

frame

tubes.

Note

the

earthing

connection

to

the

frame.

It

is

advisable

to

keep

the

drain

tray

below

the

engine

during

this

operation

since if

the

drain

plug

is

removed,

some

additional

oil

may

escape

from

the

crankcase

as

the

engine

position

is

changed.

8

Support

the

crankcase

assembly

and

withdraw

the

upper

rear

engine

bolt.

The

crankcase

assembly

is

now

free

to

be

removed

from

the

frame

and

can

be

lifted

out

from

the

right

hand

side

of

the

machine,

leaving

the

gearbox

in

position.

10

Dismantling

the

engine -removing

the

contact

breaker

and

auto-advance

assembly

With

the

crankcase

assembly

out

of

the

frame,

it

is

preferable

to

devise

some

form

of

bench-mounting

engine

stand

so

that

the

engine

can

be

held

rigidly

on

the

workbench

during

the

final

stages

of

dismantling

and

during

the

early

stages

of

reassembly.

This

will have

the

advantages

of

leaving

both

hands

free

to

continue

the

dismantling

work

and

providing

better

access.

As

an

alternative,

remove

the

long

bolt

which

passes

through

the

base

of

the

crankcase

assembly

and

grip

the

unit

in a vice

fitted

with

soft

aluminium

clamps.

2

Remove

the

two

screws

which

retain

the

circular

contact

breaker

cover

in

position

and

lift

away

the

cover.

Remove

the

centre

bolt

of

the

contact

breaker

cam,

the

serrated

washer

and

the

plain

washer.

The

cam

can

now

be

extracted

from

its

taper

by

using

Norton

Villiers

service

tool

060934.

If

this

tool

is

not

available,

the

cam

can be

released

by

screwing a 5/16

inch

UNF

bolt

into

the

thread

tapped

within

the

cam

orifice.

3

There

is

no

necessity

to

remove

the

contact

breaker

baseplate

before

the

timing

cover

is

removed

but

if

attention

to

this

component

is

necessary,

it

is

secured

by

either

two

screws

or

two

hexagonal

pillars.

Unscrew

the·

two

screws

or

pillars

and

lift

the

contact

breaker

assembly

away.

The

contact

breaker

lead

wire will pull

through

the

passageway

in

the

contact

breaker

housing.

11

Dismantling

the

engine -removing

the

timing

cover,

oil

pump

and

timing

chain

Remove

the

twelve

SCrews

which

retain

the

timing

cover

in

position

and

free

the

cover

by

giving a

gentle

tap

from

behind

the

pressure

release valve

with a rawhide

mallet.

Lift

the

timing

cover

away

and

withdraw

the

two

locating

dowels

at

the

front

and

rear

of

the

timing

chest

which

may

otherwise

be

displaced

during

the

following

operations.

2

Remove

the

two

nuts

which

retain

the

oil

pump.

The

pump

may

be a tight

fit

on

the

two

mounting

studs

and

is

best

released

by

rotating

the

oil

pump

drive

pinion

so

that

it

will

travel

along

the

worm

drive

of

the

cran

kshaft

and

ease

itself

off

the

studs.

3

The

drive

worm

is

integral

with

the

left

hand

thread

nut

on

the

end

of

the

crankshaft.

Lock

the

engine

by

placing a stout

metal

bar

through

the

small

ends

of

both

connecting

rods,

then

slacken

the

nut

in a

CLOCKWISE

direction

with a socket

spanner.

The

nut

is

tight

and

some

force

may

be

necessary

to

start

it

moving.

4

Whdst

the

engine

is still

locked

in

position,

slacken

the

nut

retaining

the

camshaft

sprocket.

This

has a

normal

right

hand

thread

and

it

will

be

necessary

to

re-arrange

the

method

of

locking

the

engine

since

this

nut

will

turn

in

the

opposite

(anti-

clockwise)

direction.

Use

steady

and

not

excessive

force,

otherwise

the

intermediate

gear

spindle

may

be

forced

out

of

the
crankcase.
5

Because

the

timing

chain

is

of

the

endless

variety,

the

two

sprockets

and

chain

must

be

removed

in

unison.

If

the

camshaft

sprocket

is a

little

tight

on

the

end

of

the

camshaft,

it

can

be

8.11 c Remove

woodruff

key

to

prevent

misplacement

8.12

Chaincase

rear

is

retained

by

three

bolts

and

tab

washers

21

~------------------------------------------------------------------~

CWTCH COMPLETE

40

FIG.

1.2.

PRIMARY

TRANSMISSION

1 Inner chaincase

complete

with

dowels

2 Chaincase oil seal disc 2

off

3 Chaincase

dowel 2 off

4 Chaincase

felt

seal

5 Chaincase

gasket

6 Chaincase

bolt 3 off

7 Tab washer 3

off

8 Chaincase

centre

stud

9 Chaincase

centre

stud

washer 2

off

10 Chaincase

centre

stud

nut

11

Chaincase

centre

stud

shim -number

as required

12

Stator

stud 3 off

13

Stator

stud

spacer 3

off

14

Stator

stud

washer 3

off

15

Stator

stud

nut 3 off
160uterchaincase
17 Ignition

indicator

plate

18

Hammer

drive

screw 2 off

19 Chain

inspection

cap

20

'0'

ring for chain

inspection

cap

21

Timing

inspection

cap

22

'0'

ring for

timing

inspection

cap

23

Chaincase sealing

rubber

24

Chaincase

attachment

nut

25

Chaincase

attachment

nut

washer

26

Engine

sprocket

27

Engine

sprocket

key

28

Alternator

rotor

29

Alternator

stator

30

Alternator

leadwire

grommet

31

Rotor

spacer

32

Rotor

shim

0.010

in.

number

as required

33

Rotor

shim

0.036

in.

number

as required

34

Rotorkey

35

Rotor

washer

36

Rotor

nut

37

Primary drive chain

38

Chaincase oil level plug

39

Oil level plug

'0'

ring

40

Clutch assembly cOl;nplete

41

Clutch

sprocket

complete

with

backplate

42

Clutch friction plate 4

or 5 off,

depending

on

type

43

Clutch plain plate 3

or 4 off,

depending

on

type

of

friction plate

44

Clutch pressure

plate

45

Clutch

centre

46

Clutch diaphragm with

centre

47

Clutch adjuster

48

Clutch adjuster

locknut

49

Clutch

centre

bearing

50

Clutch bearing

inner

circlip

51

Clutch bearing

outer

circlip

52

Clutch diaphragm circlip

53

Clutch

location circlip

54

Clutch location spacer

55

Clutch location

shim

0.036

in.

number

as required

56

Clutch location

shim

0.048

in.

number

as required

57

Clutch retaining

nut

58

Clutch retaining

nut

washer

59

Final drive chain -

98

links,

19

tooth

sprocket

or

99

links,

21

tooth

sprocket

60

Clutch retaining

nut

tab washer

Chapter

1/Engine

eased

off

with a pair

of

tyre

levers,

taking

care

not

to

bruise

the

sealing

face

of

the

timing

cover

joint.

12

Dismantling

the

engine -

removing

the

crankshaft

pinion

and

separating

the

crankcases

It

is

essential

to

use

Norton

Villiers service

tool

ET

2003

to

remove

the

crankshaft

pinion

because

it

is

necessary

to

have a

straight

pull.

There

is

insufficient

room

behind

the

pinion

to

insert a conventional

two

or

three

legged

puller.

Any

other

method

of

removal will

almost

inevitably

cause

damage.

2 When

the

pinion

has been

withdrawn,

the

Woodruff

key

and

backing

washer

can

be

lifted

off

the

crankshaft.

There

is a lipped

oil sealing disc

which

tends

to

cling

to

the

right

hand

main

bearing

due

to

the

residual oil

film.

This

washer

is

best

removed

by

two

small

magnets.

If

desired,

the

chain

tensioner

can be

removed

at

the

same

time.

It

is

held

by

two

bolts

and

washers.

Mark its

position

to

ensure

correct

chain

tension

on

replacement.

3

The

crankcase

assembly

must

now

be

removed

from

either

the

engine

stand

or

vice in

which

it

is

held,

so

that

the

crankcases

can

be

parted.

They

are

held

together

by

two

studs,

one

bolt

and

two

setscrews. When all

of

these

fixings have been

removed,

part

the

crankcases

by

tapping

with a bar

of

wood

(such as a

hammer

handle)

against

the

left

hand

crankcase

mouth.

It will

be

noted

that

as

the

left

hand

crankcase

is

lifted

away,

the

rotary

breather

disc

and

spring will be

displaced

from

the

camshaft

bush

(pre·

1972

modelsl.

4

Withdraw

the

camshaft

from

the

right

hand

crankcase,

taking

care

not

to

lose

the

chamfered

thrust

washer.

Engines

with

a

number

above

200000

have

an

arrangement

comprising

two

thrust

washers

with

tabs

that

engage

with

holes in

the

crankcase.

5 It is

preferable

to

ease

the

right

hand

crankcase

from

the

crankshaft

rather

than

vice versa.

The

most

effective

means,

which

obviates

striking

the

end

of

the

crankshaft,

takes

the

form

of a spacer

in

the

form

of a hollow

tube

which

abuts

against

the

crankshaft

shoulder.

If

the

crankcase

is

rested

on

the

workbench,

inner

face

uppermost,

the

spacer

will

permit

the

crankcase

to

be

driven

off

the

crankshaft

by

hammering

downwards

on a block

of

soft

wood

pressed against

the

crankcase

casting. This

is

an

operation

requiring

the

assistance

of a second

person,

one

to

hold

the

crankcase

and

crankshaft

assembly

and

one

to

drive

the

crankcase

in a

downwards

direction.

The

alternative

is

to

heat

the

crankcase

so

that

the

right

hand

main

bearing

is

displaced

with

the

crankshaft

assembly,

to

be

drawn

off

at a later

stage,

if desired.

6 Engines

with a number

over

200000

are

fitted

with

a roller

bearing

in

the

right

hand

crankcase

and

in

this

instance

there

is

no

problem

in removing

the

crankshaft

assembly.

This also

applies

to

the

850

cc.

7

The

camshaft

bushes

need

not

be

removed

unless

wear

necessitates

their

renewal.

The

bushes

have an

extremely

long life

under

normal

service

and

require

special

machining

facilities

when

renewal is necessary, a

task

requiring

expert

attention.

8

The

main

bearings are

best

removed

from

the

crankcases

by

heating

the

area

around

the

bearing

housing

and

either

drifting

them

out

of

position

or

by

bumping

the

jointing

face

against

a

flat

wooden

surface

so

that

they

are

displaced

by

the

shock.

A

blow

lamp

is

particularly

suitable

for

this

task,

but

on

no

account

use a

welding

torch

otherwise

the

alloy

will

melt.

13

Examination

and

renovation·

general

Before

examining

the

parts

of

the

dismantled

engine

for

wear,

it

is

essential

that

they

should

be

cleaned

thoroughly.

Use a

petrol/paraffin

mix

to

remove all

traces

of

old

oil

and

sludge

that

may

have

accumulated

within

the

engine

and

a cleansing

agent

such

as

Gunk

or

Jizer

for

the

external

surfaces.

Special

care

should

be

taken

when using

these

latter

compounds,

which

require a

water

wash

after

they

have

had

time

to

penetrate

the

film of grease

and

oil. Water

must

not

be

allowed

to

enter

any

of

the

internal

oilways

or

parts of

the

electrical

system.

Fig.

1.3.

Tool

for

compressing

clutch

diaphragm

spring

9.2

Rocker

feed

pipe

is

attached

to

rear

of

timing

cover

9.3

Rear

bolt

acts

as

earthing

connection,

behind

alloy

plate

23

9.4

Early models have

breather

attached

to

crankcase

9.5

Align head

of

mounting

bolt

to

clear

crankcase casting

~

9.6

Pull engine

mounting

downwards

to

clear

frame

9.7

Note

earth

connection

to

lower rear engine

bolt

9.8

Tilt engine forwards,

then

...

9.8a ... lift

out

of

engine plates

Chapter 1/Engine

25

10.2

Remove

two

retaining

screws

to

free

base

plate

assembly

11.2

Oil

pump

is

retained

by

two

nuts

11.5

Lift

off

timing

chain

and

sprockets

in

unison

10.2a

Use a

5/16

in

UNF

bolt

to

extract

cam

and

auto-advance

unit

11.3

Crankshaft

pinion

has a

LEFT

HAND

thread

2

Examine

the

cran kcase casti ngs

for

cracks

or

other

signs

of

damage.

If a

crack

is

discovered,

it

will require specialist

repair,

or

the

renewal

of

both

crankcases.

Crankcases are

supplied

in

matched

pairs since

it

is

considered

bad

engineering

practice

to

renew

only

one.

Under

these

latter

circumstances

there

can

be

no

guarantee

that

the

main

bearing housings have been

bored

exactly

in

line

with

one

another.

3

Examine

carefully each

part

to

determine

the

extent

of

wear,

if necessary

checking

with

the

tolerance

figures

listed

in

the

Specifications

section

of

this

Chapter.

The

following

sections

of

this

Chapter

describe

how

to

examine

the

various

engine

components

for

wear

and

how

to

decide

whether

renewal is

necessary.

4 Always use a clean, lint-free rag

for

cleaning

and

drying

the

various

components

prior

to

reassembly,

otherwise

there

is

risk

of

small particles

obstructing

the

internal

oilways.

14

Crankshaft,

big

end

and

engine

bearings -examination

and

renovation

Check

the

big

end

bearings

for

wear

by

pulling

and

pushing

on

each

connecting

rod

in

turn,

whilst

holding

the

rod

under

test

in

the

vertical

plane.

Although

a small

amount

of

side

play

is

permissible,

there

should

be

no

play

whatsoever in

the

vertical

direction

if

the

bearing

concerned

is

fit

for

further

service.

2

The

big

end

bearings

take

the

form

of

shells.

To

gain access

to

the

shells, remove

the

connecting

rods

by

unscrewing

the

two

self-locking

nuts

at

each

end

cap.

When

the

nuts

have

been

withdrawn

completely,

the

connecting

rod

and

end

cap

can

be

pulled

off

the

crankshaft,

with

the

bearing shells still

attached.

Mark

both

the

connecting

rods

and

their

end

caps

clearly

so

that

there

is

no

possibility

of

them

being

interchanged.

Note

that

the

locating

tabs

of

the

bearing shells

fit

to

the

same

side

of

each

connecting

rod.

3 If

the

crankshaft

assembly

is

to

be

separated,

it

is

advisable

to

continue

the

dismantling

in a clean metal

tray.

The

assembly

26

----------.,

FIG.

1.4.

CRANKSHAFT

ASSEMBLY

AND

TIMING

GEAR

1

Connecting

rod

with

cap 2 off

2

Connecting

rod

bolt 4 off

3

Connecting

rod

self-locking

nut 4 off

4

Birrend

shell

set 2 off

5

Crankshaft

complete -850

cc

models

6

Crankshaft

complete -750

cc

models

7 Crank cheek,

timing

side -

750

cc

models

only

8 Crank cheek,

drive

side -

750

cc

models

only

9

Flywheel-

750

cc

models

only

10

Dowel

11

Nut

retaining

plate 2 off

12

Crankshaft

stud 4 off

13

Crankshaft

stud

nut 8 off

14

Crankshaft

stud 2 off

15

Crankshaft

stud

nut 4 off

16

Crankshaft

oil

way

screw

17

Crankshaft

pinion

18

Crankshaft

pinion

key

19

Crankshaft

pinion

backplate

20

Oil

pump

worm

21

Camshaft

22

Camshaft

thrust

washers 2

off

23

Intermediate

gear

complete

with

bush

and

sprocket

24

Intermediate

gear bush

25

Intermediate

gear

shaft

26

Intermediate

gear

shaft

circlip

27

Camshaft

sprocket

28

Camshaft

sprocket

key

29

Camshaft

sprocket

nut

30

Camshaft

chain

31

Tensioner

slipper

32

Tensioner

backing

plate -thin

33

Tensioner

backing

plate -thick

34

Tensioner

stud 2 off

35

Tensioner

stud

washer 2

off

36

Tensioner

stud

nut 2 off

37

Piston

complete

(left

hand)

750

cc

only

38

Piston

complete

fright

hand}

750

cc

only

39

Piston

complete -850

cc

models

only 2 off

40

Piston

ring

set -750

cc

models

only 2 off

41

Piston

ring

set -850

cc

models

only 2 off

42

Gudgeon

pin -850

cc

models

only 2 off

43

Gudgeon

pin -750

cc

models

only 2 off

44

Circlip 4 off

45

Lipped

sealing washer,

timing

side

bearing

27

28

Chapter 1/Engine

holds

approximately

one

teacup

of

oil

which

will be released

when

the

cranks

are

separated

from

the

centre

flywheel.

4

Slacken

the

nuts

on

the

right

hand

(timing) side

of

the

crankshaft

assembly,

noting

that

two

of

the

nuts

are

retained

by

a

tab

washer

and

the

other

four

have been

centre-punched

to

prevent

them

from

loosening in service. All will be

tight.

5 Mark

the

central

flywheel

so

that

there

is

no

possibility

of

it

being reversed

during

subsequent

reassembly.

Jar

the

crank

flanges

from

the

flywheel

with a hammer

and a soft

metal

drift.

This will release

the

left

hand

(drive side)

crankshaft,

which will

come

away

with

the

lower

two

studs,

tab

washer

and

nuts.

If

the

machine

has

covered a considerable

mileage,

it

will

probably

be

found

that

there

is a build

up

of

sludge

in

both

crank

flanges

and

in

the

flywheel

recess as a

result

of

the

centrifugal

action

of

the

rotating

assembly.

This

must

be

cleaned

out

thoroughly

prior

to

reassembly.

6 Wash

each

crank

in

turn

with

clean

petrol

and

use

compressed

air

to

dry

off.

Light

score

marks

on

the

big

end

journals

can

be

removed

by

the

use

of

fine

emery

cloth

but

if

the

scoring

is

excessive

or

deep,

or

if

measurements

show

ovality

of

more

than

0.0015

inch

(0.0381

mm)

the

journals

must

be

reground.

The

accompanying

illustration

shows

the

regrind

sizes permissible;

shell bearings

are

available in

undersizes

to

match,

from

minus

0.010

inch

to

0.040

inch,

in

0.010

inch

stages.

The

big

end

shells

are

finished

to

give

the

required

diametrical

clearance

and

must

not

be

scraped

to

improve

the

fit.

7 Main bearing roller races

should

be

withdrawn

from

the

crankshaft

by

using

Norton

Villiers service

tool

063970.

There

is

insufficient

clearance

for

the

legs

of a sprocket

puller

or

other

substitute,

if

the

service

tool

is

not

available. Main bearing

failure

is

characterised

by a rumbling

noise

from

the

engine

and

some

vibration

which

may

not

be

damped

out

by

the

Isolastic

engine

mountings.

Bearings

of

the

ball

or

roller

type

should

be

renewed

if

any

play

is

evident,

if

the

tracks

are

worn

or

pitted,

or

if

any

roughness

is

felt

when

they

are

rotated

by

hand.

15

Timing

pinions,

timing

chain

and

chain

tensioner -examination

and

renovation

It

is

unlikely

that

either

the

timing

pinions

or

sprockets

will

require

attention

unless a

timing

chain

breakage

has

resulted

in

either

chipped

or

broken

teeth.

These

components

have an

exceptionally

long life

and

rarely

need

renewing.

2

The

timing

chain

is

of

the

endless

type

and

should

be

examined

closely

for

any

signs

of

broken

rollers

or

cracked

side

plates.

If

the

chain has

worn

unevenly,

making

it

difficult

to

adjust

the

chain

tensioner,

this

is

another

cause

for

renewal. If

there

is

any

doubt

about

the

condition

of

the

chain

it

is

wise

to

renew

it,

since a breakage

may

damage

the

timing

pinions

and

sprockets,

apart

from

completely

immobilising

the

machine.

3

Although

the

chain

tensioner

will be

grooved

from

sliding

contact

with

the

side

plates

of

the

timing

chain,

there

is

no

necessity

for

renewal

unless

the

grooves

are

deep

and

there

is

danger

of

the

rollers

making

contact.

16

Timing

cover

oil seals -

examination

and

renewal

The

inside

of

the

timing

cover

contains

two

oil seals,

one

for

the

cran

kshaft

and

one

for

the

contact

breaker

assembly.

The

presence

of

oi I

within

the

contact

breaker

housing

denotes

failure

of

the

contact

breaker

seal

which

must

be

renewed.

Close

examination

will

show

whether

the

crankshaft

seal has

remained

effective.

2

The

crankshaft

oil seal

is

retained

in

the

timing

cover

housing

by a

circlip.

When

the

circlip

is

removed,

the

seal

can

be

prised

from

the

housing.

Fit

the

new

seal

with

the

pressure side

towards

the

timing

cover

and

after

driving

it

home,

refit

the

circlip

with

its

sharp

side

towards

the

crankcase.

Avoid

scratching

the

oil

seal

housing

during

this

operation

and

check

that

the

circlip has

located

fully

with

its groove.

3

The

contact

breaker

oil seal

is

pressed

into

its

housing

without

any

retaining device. Prise

the

old

seal

out

of

position

and

fit

the

new

seal

with

the

pressure side

towards

the

crankcase

(spring
side!'
4

Since

the

oil seals are easily

damaged

if

too

much

force

is

used

when

pressing

them

home,

two

Norton

Villiers service

tools

are

avai lable

for

this

purpose.

Use

tool

063967

for

the

cran

kshaft

oil seal

and

tool

063966

for

the

contact

breaker

seal.

17

Cylinder

barrel -

examination

and

renovation

The

usual

indications

of

badly

worn

cylinder

bores

and

pistons

are

excessive oil

consumption

and

piston

slap, a metallic

rattle

which

occurs

when

there

is

little

or

no

load

on

the

engine.

If

the

top

of

the

cylinder

barrel

is

examined

carefully,

it

will be
observed

that

there

is

a ridge

on

the

thrust

side

of

each

cylinder

bore

which

marks

the

limit

of

travel

of

the

uppermost

piston

ring.

The

depth

of

this ridge will

vary

according

to

the

amount

of

wear

that

has

taken

place

and

can

therefore

be used as a

guide

to

bore
wear.
2 Measure

the

bore

diameter

below

each

ridge, using an

internal

micrometer.

Compare

this

reading

with

the

diameter

at

the

bottom

of

each

bore.

If

the

difference in readings

exceeds

0.005

inch

(0.1270

mm)

it

is

necessary

to

have

the

cylinder

barrel

rebored

and

to

fit

oversize

pistons

and

rings.

3 If an

internal

micrometer

is

not

available,

the

amount

of

wear

can

be

measured

by

inserting a compression

ring

so

that

it

is

about

%.

inch

from

the

top

of

the

bore

and

seated

squarely

in

the

bore

by

pressing

it

down

with

the

skirt

of

the

piston.

Measure

the

ring gap

with a feeler

gauge,

then

reposition

the

ring

below

the

area

traversed

by

the

piston

and

measure

the

gap

again.

Subtract

the

second

reading

from

the

first

and

divide

the

difference

by

three

to

give

the

diametrical wear. If in excess

of

0.005

inch

(0.1270

mm) a rebore

is

necessary.

4

Check

the

surfaces

of

both

cylinder

bores

to

ensure

there

are

no

score

marks

or

other

signs

of

damage

that

may

have

resulted

from

an earlier engine

seizure

or

displacement

of

one

of

the

circlips. Even if

the

bore

wear

is

not

sufficient

to

necessitate

a

rebore, a deep

indentation

will

override

this decision in

view

of

the

compression

leak

that

will

occur.

5

Check

that

the

external

cooling

fins are

not

clogged

with

road
dirt

or

oil,

otherwise

the

engine

may

overheat.

Unlike

most

other

engines

fitted

with a cast

iron

cylinder

barrel,

an

aluminium

finish

is

applied

in place

of

the

traditional

matt

black,

only

the

Combat

engine has a

black-finished

cylinder

barrel.

6

Examine

the

base flange

of

the

cylinder

barrel.

If

the

engine

has

been

overstressed

by

excessive

tuning,

the

flange

is

one

of

the

fi

rst

parts

to

fail, usually

around

the

root

of

the

bores.

If

the

flange

is

cracked,

renewal

of

the

cylinder

barrel

is

essential.

7

The

cam

followers are

located

in

the

base

of

the

cylinder

block,

where

each

pair

are

retained

by

a locating

plate

and

two

setscrews,

wired

together.

Unless

the

hardened

surface

is

badly

worn,

chipped

or

has

broken

through,

there

is

no

necessity

to

remove

them

..

Note,

however,

that

when

the

camshaft

is

renewed,

the

followers

must

also be

renewed

as a

set,

irrespective

of

their

condition.

18

Pistons,

piston

rings

and

small

ends -examination

and

renovation

If a

rebore

is

necessary,

the

pistons

and

rings

can

be

discarded

because

they

must

be

replaced

by

their

oversize

counterparts.

2 Remove all

traces

of

carbon

from

the

piston

crowns,

using a

soft

scraper

to

ensure

the

surface

is

not

marked.

Finish

off

by

polishing

the

crowns

with

metal polish,

so

that

the

carbon

will

not

adhere

so

readily.

NEVER

use

emery

cloth.

3 Piston

wear

usually

occurs

at

the

base

of

the

skirt

and

takes

the

~orm

of

vertical

streaks

or

score

marks

on

the

thrust

side.

If

a

previous

engine seizure has

occurred,

the

score

marks

will be very

obvious.

Pistons which have

been

subjected

to

heavy

wear

or

seizure

should

be

rejected

and

new

ones

obtained.

4

The

piston

ring grooves

may

become

enlarged

in use,

permitting

the

rings

to

have

greater

side

float.

It

is

unusual

for

14.4

Slacken

nuts

on

right-hand

side

of

assembly

Fig.

1.5.

Su

pporting

the

crankcase

whilst

removing

the

crankshaft

assembly

14.5

Before

crankshaft

assembly

is

separated,

mark

flywheel

to

prevent

accidental

reversal

16.2a

...

then

retained

in

position

by a circlip

16.2

Crankshaft

oil seal

is

driven"

into

position,

then

•..

16.3

Fit

contact

breaker

oil seal as

shown