Evinrude Bobcat E251C User manual

25

HORSEPOWER · MODELS E251C E251M

32

HORSEPOWER · MODEL E251 HP

743

10-70

PART

NO_

261888

LlTHO

U.S.A.

©

OUTBOARD

MARINE

CORPORATION

1970

ALL

RIGHTS

RESERVE:D

AVAILABLE

FROM

YOUR

EVINRUDE

DEALER

FUEL

RECOMMENDATIONS

The

correct

fuel

mixture

ratio

is

24

parts

of

a good

grade

gasoline

to

one

part

oil.

Use

regular

gasoline

in

Model 251

and

premium

gasoline

in

the

251

HP.

For

ease

of

measurement,

this

is

equivalent

to

one

quart

of

oil

to

six

gallons

of

gasoline,

one

pint

of

oil

to

three

gallons

of

gasoline,

or

1/ 3

pint

of

oil

to

each

gallon

of

gasoline.

Use

only

Evinrude

Lubricant

or

a

reputable

auto

motive

engine

oil,

SAE 30

MS

or

MM. Avoid

use

of low

price

third

grade

(ML

light

duty)

oils.

DO

NOT USE

MULTIPLE

VISCOSITY OILS, SUCH

AS

10W30,

OR

ANY OUTBOARD MOTOR OILS

OTHER

THAN EVINRUDE OUTBOARD

LUBRICANT.*

*EVEN THOUGH EVINRUDE OUTBOARD LUBRICANT

IS

ADVER-

TISED

AS

A 50:1 RATIO LUBRICANT, IT

IS

IMPERATIVE

FOR

SNOWMOBILE USE THAT

IT

BE

MIXED AT A 24:1 GAS-

LUBRICANT RATIO.

DO NOT

POUR

GASOLINE

OR

LUBRICANT

DIRECTLY

INTO

VEHICLE

FUEL

TANK. USE

AN

APPROPRIATE

CONTAINER

FOR

MIXING

AND

STORING THE

FUEL.

To

prepare

the

snowmobile

fuel

properly,

pour

into

aSEPARATE,

clean

container

half

the

amount

of

gasoline

required

and add

all

the

required

lubricant.

Thoroughly

shake

this

partial

mixture.

Next,

add

the

balance

of

gaso-

line

necessary

to

bring

the

mixture

to

the

required

ratio

of

24:1.

Again,

thoroughly

agitate

the

mixture.

A

clean

funnel

equipped

with

a

fine

screen

should

be

used

when

pouring

the

fuel

mixture

into

the

vehicle

tanle

24

to

1

lubricant

is

prediluted

to

provide

excellent

mixability

with

gaso-

line

at

low

temperatures.

The

addition

of

this

dilutent

does

not

in

any

way

affect

the

lubrication

qualities

of

the

lubricant.

Whenever

it

is

necessary

to

mix

fuel

and

lubricant

at

temperatures

below

O°F,

the

lubricant

should

be

prediluted

with

gasoline

to

improve

its

mixability.

The

lubricant

should

be

prediluted

with

approximately

one

part

gasoline

to

one

part

lubricant.

Predilution

of

the

lubricant

should

take

place

with

the

lubricant

temperature

above

0

°F.

Do

not

use

kerosene

or

fuel

oils

for

pre-mixing.

c

SECTION

1

INTRODUCTION

INTROOUCTION

SPECIFICATIONS

GENERAL

SNOWMOBILE

INFORMATION

TROUBLE

SHOOTING

TUNE-UP

PROCEOURES

FUEL

SYSTEM

IGNiTrON

AND

ELECTRICAL

SYSTEM

MANUAL

STARTER

ENGINE

~

__

O_R_IV_E_T_R_A_IN

__________________

~

STEERING,

TRACK

ANO

SUSPENSION

LUBRICATION

ANO

STORAGE

1-2

17000

Figure

1-1

The snow

machine

has

been

designed

and

built

for

dependable,

high )

performance.

It

is

important

to

every

snow

machine

owner

to

be

able

to

receive

skilled

and

thorough

service

for

his

vehicle

when

necessary.

It

is

important

to

the

service

dealer

to be

able

to

offer

the

type

of

skilled

service

which will

maintain

the

customer's

satisfaction.

This

manual,

together

with

the

regularly

issued

service

bulletins

and

Parts

Catalogs,

provide

the

serviceman

with

all

the

literature

necessary

to

service

the

1971

model

251 and 251HP

snowmobiles.

Pictured

be-

low

left

is

the

model

251

and

to

the

right,

the

high

performance,

251HP.

An

effort

has

been

made

to

produce

a

manual

that

will

not

only

serve

as

a

ready

reference

book

for

the

experienced

service

man,

but

will

also

provide

more

basic

information

for

the

guidance

of

the

less

ex

-

perienced

man.

The

Parts

Catalogs

contain

complete

listings

of

the

parts

required

for

replacement.

In addition,

the

exploded

views

illustrate

the

correct

sequence

of

all

parts.

This

catalog

can

be

of

considerable

help

as

a

.

reference

during

disassembly

and

reassembly.

The

Section

Index on

page

1-1

enables

the

reader

to

locate

quickly

any

desired

section.

At

the

beginning

of

each

Section

is

a

Table

of

Contents

which

gives

the

page

number

on

which

each

topic

begins.

This

arrange-

ment

simplifies

locating

the

desired

information

within

this

manual.

Section

2

lists

complete

specifications

on

the

1971

snowmobiles.

All

general

information,

including

2

cycle

engine

theory,

trouble

shooting,

and

tune up

procedures,

are

given

in

Sections

3

through

5 of

this

manual.

17022

Figure

1-2

-

c

(

Sections

6

through

11

provide

fully

illustrated,

detailed,

step-by-step

disassembly

and

reassembly

instructions

and

adjustment

procedures.

Section

12

provides

lubrication

and

storage

information.

In

this

way,

the

texts

treat

each

topic

separately;

theory

and

practice

are

not

inter

mixed.

This

makes

it

unnecessary

for

the

experienced

service-

man

to

reread

discussions

of

theory

along

with

specific

service

in-

formation.

illustrations

placed

in

the

margins

provide

unimpeded

reading

of

explanatory

text,

and

permit

close

relationship

between

illustration

and text.

Read

this

manual

carefully

to

become

thoroughly

familiar

with

the

procedures

described,

then

keep

it

readily

available

in

the

service

shop

for

use

as

a

reference.

If

properly

used,

it

will

enable

the

serviceman

to give

better

service

to

the

snow

machine

owner,

and

thereby

build

or

maintain

areputation

for

reliable

service.

This

service

manual

covers

all

phases

of

servlcmg

the

1971

snow-

mobiles,

without

reference

to

other

information;

however,

new

service

situations

sometimes

arise.

If

a

service

question

does

not

appear

to

be

answered

in

this

manual,

you

are

invited

to

write

to

the

Service

Depart-

ment

for

additional

help.

Always

be

sure

to

give

complete

information,

including

model

number

and

vehicle

se

rial

number.

All

information,

illustrations,

and

specifications

contained

in

this

literature

are

based

on

the

product

information

available

at

the

time

of

publication.

The

right

is

reserved

to

make

changes

at

any

time

without

notice.

17002

1. Hood

Latch

(Wing Nut)

6.

Hand

Brake

with

2.

Neutral

Lockout

Knob

Parking

Lock

3.

Headlight

Connector

7.

Throttle

Lever

4.

Ignition/Lights

Switch 8.

Primer

5.

Compression

Relief

9.

Manual

Start

Handle

Figure

1-3

-

).

)

---

~-

---

.......

c

SECTION

2

SPECIFICATIONS

TABLE

OF

CONTENTS

SPECIFICATIONS

............•.•...

2- 2

TORQUE

SPECIFICATIONS

. . . . . . . • . . . .

2-3

2-1

2-2

For

your

own

protection,

before

proceeding

with any

repair

or

adjustments

on

these

snowmo-

biles,

see

on

pages

4-7,6-6,7-7,

8-2,

9-2,

9-6

and

11-4.

SPECIFICATIONS

CAUTION: Snowmobiles

are

not

manufactured

for

highway

use

and

the

manufacturer

does

not

represent

that

they

are

equipped

with

all

the

de-

vices

legally

required

for

such

use.

Length Model

251

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

96

inches

Model

251

HP

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

..

98

inches

Width

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

32-9

/16

inches

Height Model

251

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

42

inches

Engine

Rating

Model

251

HP

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

..

37-1/2

inches

. . . . . . . . . . . . . . . . . . OMC

2-cycle

opposed

twin

Model

251

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

Maximum

25

HP

at

5300

RPM

Model

251

HP

..........

. .

Maximum

32

HP

at

6200

RPM

Starter

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

Manual,

rewind

Clutch

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

Centrifugal

operated

sheave

engages

belt

Drive

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

Variable-speed,

V-belt

and

chain

Drive

Sprocket

Ratio

(Standard) . . . . . . . . . . . . . . . . . . .

..

16

to

30

Options

..

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

..

11, 13, 15

or

18

to

30

Transmission

.........

Variable

speed,

3:1 to 1:1

ratio

Forward

only

Mufflers

Model

251

...

Single

Tuned

engine

muffler

for

quiet

operation

Model

251

HP

..

Dual

Tuned engine

mufflers

for

maximum

Brake

.

Throttle

....

Track

....

.

Width:

..

.

Skis

.....

.

performance

· . . . . . . .

.......

Disc

type,

hand

operated

· . . . . . . . . . . . . . . . . . . . . . . . .

thumb

operated

· . . . . . . . . .

Specially

designed

fully

adjustable

· . . . . . . . . . . . . . . . . . . . . . . . .

..

15-3/8

inches

. . . . . .

Formed

steel,

equipped with

shock-absorbing

Seating

capacity

...

leaf

springs

and

replaceable

wear

runners

..

....

Two

adults.

Vinyl

coated

twill

cover,

molded

urethane

foam

cushion

Hood

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

Molded

fiberglass

with

built-in

headlights

Lighting

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

2

Headlights,

and

taillight

Fuel

tank

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

..

6 U.S.

gallons

Fuel

Model

251

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

good

grade

regular

Model 251

HP

. . . . . . . . . . . . . . . . . . good

grade

premium

Lubrication.

. . . . . . . . . . . . . 24:1

using

Evinrude

24

to 1

lubricant

or

SAE 30

MM

or

MS

oil

Carburetor

Needle

Adjustment

High

speed

........

.

Low

speed

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

.

RPM

Ratings

. . . . .

..

1

turn

off

seat

1

to

1-1/4

turns

off

seat

Idle

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

. 1100 -1300

2300 -2400

2600 -2800

Transmission

Belt

Engaging Speed Model 251

.......

.

Model 251

HP

Ignition

Breaker

point

gap.

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

..

.022 to .024

Spark

plug Model 251

...........

Champion

J7J

or

equivalent

Model 251

HP

........

Champion

J4J

or

equivalent

Spark

plug

gap.

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

..

.028 -.032

inch

Condenser

capacity

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

.18 -.22

mfd

Magneto

driv~

coil

resistance.

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

..

.8

ohm

Ignition

coil

primary

resistance

......

. . . . . . . . . . .

..

1. 5

ohm

Ignition

coil

secondary

resistance

. . . . . . . . . . .

..

10,000

ohms

Lighting Coil

resistance

....

.678 to .562

ohm

Engine

Bore

and

stroke

......

'. . . .

2-3/4

x

2-1/4

inches

Piston

displacement

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

..

437

cc

or

26.7

cubic

inches

Compression

ratio

Model 251

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

7

to

1

Ring

diameter

....

Ring

thickness

. . . .

Cylinder

Compression

Model 251

HP

. . . .

.........

8

to

1

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

..

2-3/4

inches

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

..

1/16

inch

Model 251

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

.

minimum

105

PSI

minimum

120

PSI

Model 251

HP

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

.

Clearances

Piston

-

wrist

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

.......

Press

fit

Piston

ring

gap.

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

.007

-

.017

Piston

ring

-

ring

groove

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

.002

-.004

Cylinder

-

piston

...........

Top of

piston

to

cylinder

.012 -.014

Bottom

of

piston

to

cylinder

.006 -.010

Specifications

and

features

may

be

changed

at

any

time

without

notice

and without

obligation

towards

vehicles

previously

manufactured.

---)

)

c

TORQUE

SPECIFICATIONS

PART

APPLICATION

SIZE TORQUE

IN./

FT.

/

LBS. LBS.

Screw

Brake

Hand

Lever

#10-32

13-15

Screw

Coil

Clamp

to

Main

Frame

35-45

*

Screw

Connecting

Rod 29-31

*

Screw

Crankcase

60-80

6-7

* Nut

Cylinder

Base

16-20

*

Screw

Engine

to

Engine

Frame

Assembly

33-38

* Nut

Flywheel

40-45

* Nut

Engine

Frame

to

Main

Frame

3/

8-16

18-20

* Nut

Front

and

Rear

Truck

Axles

5/

8-18

50-60

*

Screw

Idler

Axle

to

Frame

5/8-18

20-25

Bolt

and

Nut

Rear

Axle

Pivot

12-15

Setscrew

Rear

Sprocket

18-20

Nut

Rear

Suspension

to

Frame

12-15

* Nut

Runner

to

Ski

90-100

* Nut

Saddle

to

Spring

3/8-24

25-30

Spark

Plug

20-20-1

/ 2

Nut

Throttle

Control

Cable

30-40

* Nut

Tie

Rod

3/

8-24

18-20

*

Screw

Truck

to

Frame

(Cleated

Track

Models)

3/

8-16

25-30

*

Screw

Truck

to

Frame

(Molded

Track

Models)

7/16

25-30

* Nut

Steering

Arm

to

Ski

Column

3/

8-24

18-20

*

Bolt

(Early

Primary

Bolt

to

End

Cap

70-80

MOdels)

*

Bolt

(Later

Primary

Bolt

to

End

Cap

90-100

MOdels) (Has

annular

groove

in

Screw

head).

See

Figure

2-1

#6

7-10

Screw

#8

15-22

Screw

#10

25-35

2-3

Screw

#12

35-40

3-4

Screw

1/4

60-80

5-7

Screw

5/16

120-140

10-12

Screw

3/8

220-240

18-20

Specifications

and

features

may

be

changed

at

any

time

without

notice

and

without

obligation

towards

vehicles

previously

manufactured.

*Use

Torque

Wrench

2- 3

ANNULAR

GROOVE

1

7192

Figure

2-1

)

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

Evinrude Bobcat E251C User manual

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