Yamaha RD250 User manual

MODEL GUIDE

PREStrNTATION Dtr MODtrLtr

MODELLANLEITUNG

90894- 09025

NOTE: INFORMATION AND OTHER TECHNICAL DATA (tNCLUDtNG SpECtFtCAT|ONS) tN THtS

MODEL GUIDE MAY BE SUBJECT TO CHANGE WITHOUT PRIOR NOTICE.

A. FEATURES

@urcur pERFoBMANcE ENGTNE wtrH

_ NEW CYLINDER

- NEW EXHAUST MUFFLER

- c.D.t.

_ BIGGER CARBURETOR

@sorr roucH opERATtoN oF cHANGE eEDAL

@cnsrrruc wHEEL wtrH BLAcK coATtNG

@serren RTDTNG posrrroN wtrH NEW HANDLEBARS

AND FOOT RESTS

I.D. & ENGINE/FRAME NUMBER

MODEL NAME l.D. Nos, E/G STARTING Nos. AREAS

RD250 2R8 1A2-220101 A, B, DK, NL, CH, UK

RD25O 2TO 1A2-310101 D

RD25O 2T'l 2T1-000101 F

R D4OO 2R9 143-110101 A, B, DK, UK, SF, D, NL, S, CH

RD4OO 2T2 2T2-OOO101 F

f,_

B. DIFFERENCES FROM 1977 MODEL

MODIFICATION

IENGINE SECTION]

1. Kick starter has been changed from the ratchet

REMARKS

Better function

Easy operation

type to the Bendix type.

Primary driven geer width has been reduced.

A dimension: 15 mrn-12 mm

Carbu retor

a. Synchronizationport

-2-

MODIFICATION

b. Carburetor setting

RD25O ,77 MODEL ,78 MODEL

MODEL VM28SS <-

I,D. No. 1 5200 2 R800

MJ # 115 <_

AJ 1.0 0.8

JN 5L3-2 5L1-4

NJ o-8 o-6

CA 2.5 2.O

AS 1% <_

GS #70 <-

NOTE: The above specification may be changed without

prior notice.

RD4OO '77 MODEL ,78 MODEL

MODEL VM28SS <-

l.D. No. 14300 2R900

IVIJ # 120 # 145

AJ 0.5 <-

JN 5L1-3 5J6-3

NJ P-2 o-8

CA 2.5 <-

PJ 25 <-

AS 1% <_

GS #70 <_

NOTE : The above specifications may be changed without

prior notice.

For better engine performance the shape of

transfer port and inlet port timing have been

changed.

RD25O

REMARKS

Easy engine setting

|r)r

\- +'

@ lnlet port

@ E"harst port

@ Scauenging ports

- (Transfer)

PORT TIMING (MM}

,77 MODEL ,78 MODEL

A 29.5 <-

B62.5 665

MODIFICATION

C tntet port

@ Exhaust port

@ Scauenging ports

(Transfer)

REMARKS

Due to change of inlet

port timing

Better engine

perf ormance

5. MANIFOLD (For RD400 ON LY)

For better engine performance, both right and

left manifolds are provided with balance pipe. t

7have been

PORT TIMING (MM)

77 MODEL ,78 MODEL

A33.5 <_

B395 41 5

c640 68.5

trN

ocn

ffiffi.)

PISTON (For RD400 ONLY)

Change in shape

EXHAUST PIPE & MUFFLER

Both inside diameter and volume

changed.

MODIFICATION

IELECTRTCAL SECT|ONI

1. Modification of lgnition system

Battery lgnitio

2. lgnition coil 2 coils- 1 coil

3, Voltage regulator and rectifire

Separate type ..------ lntegrated type

C.D.l. lgnition timing adjustment procedures.

C.D.l. lgnition

1. lnstall dialgauge to left side spark plug

hole.

2. Rotate crankshaft countrclockwise up

to T.D.C. and slowly turn it clockwise

until dialgauge indicates the specified

spark advance position.

R D250 BTDC 2.00 l- 0.1 5 mm

R D400 BTDC 2.30 1 0.1 5 mm

3. At this time, adjust magneto base

using screw driver until both marks

(lF, l) become alignment.

REMARKS

Better engine

performance

Not interchangeable

Due to use of CDI

Prevention of plug

from coming off

4. Spark plug cap with rubber ring.

Screw driver

lry Rubber ring

MODIFICATION REMARKS

IFRAME SECTION]

1. Caliper Ass'y (Front & Rear)

Change of operation method

Fixed caliper type-----> Floating caliper type

(Tow pistons)

2. Front fork Ass'y

Fork Travel

lnner tube

diameter

(One piston)

120 mm------->140 mm

344 ------------> 354 t

3. Better riding comfort due to change in riding

position by changing the mounting position of

handlebars and footrests.

POSITION ,77 MODEL ,78 MODEL

@570 mm 576 mm

G) 202 196

@500 500

o199 224

o00 e:30'

C. GENERAL SPECIFICATION

D. SERVICE DATA

\',

RD25O RD4OO

DCH, DK. F

UK, NL, ABD, CH, SSF, DK, F

UK, NL, A, IB

DIMENSIONS/WEIGHT

Overall length

Overall width

Overall height

Wheelbase

Minimum ground clearance

Machine net weight

2,030 mm

760 mm

1,060 mm

1,320 mm

150 mm

172 kg

2,015 mm

(CH. DK)

1,995 mm

(UK, NL)

145 mm (CH,

DK, UK, N L, D,

F)150 mm (A)

170 kg (CH, DK)

172 kg lF , UK,

NL, A}

1,955 mm

(F, A, B}

1,325 mm

'I 5O mm

170 ks

2,030 mm

<-_

760 mm

1,060 mm

1,320 mm

'l 5O mm

174 kg

2,Ol 5 mm

(DK)

1,995 mm (F,

NL, UK, I, A}

172

174 ks (DK)

1,995 mm

1,325 mm

174 ks

ENGINE

Type

Bore/Stroke

Displacement

Compression ratio

Starting svstem

Lubricating system

2 cycle aircooled

54x54

247 cc

N,A

Kick starter

Automatic

separate

6,2 <_

<--

64x62

398 cc

6,2

<-_

CLUTCH

Type

Primary drive system

Primary drive ratio

Wet multiple

disk

Gear

6A121

Gear

66123

TRANSMISSION

Type

Reduction ratio 1st

2nd

3rd

4th

5th

6th

Constant mesh

36114

32118

29122

26124

25126

24127

<-_

<--

<-_

SECONDARY DRIVE

Type

Reduction ratio Chain

38117 <_

<_. <-

36117 <-

35/17 <-

<- <_

361't7

ELECTRICAL

lgnition type c.D.t. <- <- <- <- <-

CARBURETION

Type

Effective venturi size

Main jet

Needle jet

Jet needle

Air screw (Turns out)

Cut away

VM285S

#tts

o-64

5L14

't%

2.O

<--

vM28SS

#tqs

o-8

5J6-3

2.5

VOLUMES/TYPE FLUID

Gasoline tank

Transm ission 16.5 e

1.5 e <-

<_ <-

<_ 16.5 e

1.5 e <_

<_ <_

-7-

MEMO

Oul

-8

YAIYIAHA MOTOR (C(O., LTD, Y

PRINTED IN JAPAN

??to 28x1c

(4.1/^)

IWATA,.IAPAN

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