Maico SQUARE BARREL Service Manual

SQUARE BARREL

SQUARE BARREL

ENGINE SECTION

NOTE: ALL THREADS ARE RIGHT HAND

(Clockwise to tighten - counter

clockwise to loosen).

Square Barrel Engine Manual Service Manual

MAICO

Service Manual

ENGINE SECTION

NOTE: ALL THREADS ARE RIGHT HAND

(Clockwise to tighten - counter

clockwise to loosen).

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I. Preparation For Disassembly Of The

Engine

1. All dirt, mud, dust, and foreign
material must be thoroughly re-
moved from the exterior of the en-
gine assembly before removal and
disassembly.

II. Engine Removal And Disassemblv

1.

Drain the transmission oil by re-

moving the drain plug located at

the underside of clutch cover just

ahead of the foot rest. The plug
has a 17 mm hex. Remove foot rests.
The transmission/Primary holds lOOOcc (1 Liter).

2. Remove carburetor - medium screw
driver.

Note: Disconnect wire to coil if motor-

cycle is equipped with external
coil. The coil is located under

the gasoline tank.

Square Barrel Engine Manual Service Manual

I. Preparation For Disassembly Of The

Engine

1. All dirt, mud, dust, and foreign
material must be thoroughly re-
moved from the exterior of the en-
gine assembly before removal and
disassembly.

II. Engine Removal And Disassemblv

1.

Drain the transmission oil by re-

moving the drain plug located at

the underside of clutch cover just

ahead of the foot rest. The plug
has a 17 mm hex. Remove foot rests.
The transmission/Primary holds lOOOcc (1 Liter).

2. Remove carburetor - medium screw
driver.

Note: Disconnect wire to coil if motor-

cycle is equipped with external
coil. The coil is located under

the gasoline tank.

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11. Remove the ignition cover - me-
dium blade screw driver. Not
necessary for transmission re-
pair.

12. Remove the three screws holding
the magneto housing - medium

blade screw driver. Not neces-

sary for transmission repair.

13. Remove the electrical wire going

to the coil from the points and
pull through the case removing

the rubber grommet.

Square Barrel Engine Manual Service Manual

11. Remove the ignition cover - me-
dium blade screw driver. Not
necessary for transmission re-
pair.

12. Remove the three screws holding
the magneto housing - medium

blade screw driver. Not neces-

sary for transmission repair.

13. Remove the electrical wire going

to the coil from the points and
pull through the case removing

the rubber grommet.

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Square Barrel Engine Manual Service Manual

14. Remove the magneto rotor - small

blade screw driver, Bmm wrench,

impact slide hammer puller. We
recommend the use of a slide hammer
puller as shown.

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15. Remove cylinder head - 13mm
socket.

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16. Remove cylinder

Square Barrel Engine Manual Service Manual

NOTE: To remove cylinder with engine in

the frame, remove the studs with a
small vise grip pliers. Push the

piston to SDC and remove the cylinder.

17. Remove pin clips - needle nose pliers.
Push pin through and remove piston
and bearing. Note the shop towel in
the top of cases to keep foreign
objects from falling into the lower end.
Do not reuse piston pin clips.

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Square Barrel Engine Manual Service Manual

18. Place engine in engine stand
with clutch cover up.

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Square Barrel Engine Manual Service Manual

19. Measure the piston and measure
the cylinder bore. If the cylin-
der bore is greater than .006
inch, replace the piston. It is

wise to check the cylinder bore

in at least 3 places; top, mid

and bottom to be sure that the
cylinder is round and is true
from top to bottom.
Rebore when the total deivation
in the cylinder is greater than

.006 inch from a new piston.

A new piston shall have .002 inch

clearance between piston and

cylinder wall measured at bottom
of skirt. The machine will re-
quire 75-100 miles break in prior
to racing.

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20. The piston rings shall be check-
ed for end gap. A new ring has

.010 inch end gap. When end gap

.016

exceeds

inch replace piston

rin~s.

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Square Barrel Engine Manual Service Manual

21. Remove:

A. Kick starter

1. 360-250 - Remove snap ring
and loosen pinch bolt -

ice pick and l7mm wrench.

2. 400-501 - Remove 6mm bolt
10mm wrench.

B. Remove seven 6mm screws from

the cover - medium blade

screw driver.

C. Pull the cover straight up

Note: For serv1c1ng clutch with en-

gine in the frame, lay the

machine over with the right

side down. Pull the plastic

.transmission vent hose out of

the case just above the chain.

Turn the hose

transmission oil will not run

out. Having the motorcycle

level will greatly assist

when replacing the clutch springs.

180

0

so that

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22. Remove the clutch snap rings
with special puller and two
small blade screw drivers.

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new .075 - replace .070

Square Barrel Engine Manual Service Manual

23. Remove
clutch guide, and note direction

of fiber plate and spring stack
up.

by

hand the clutch plates,

2~. Clutch spring height

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25. Clutch spring heavy 360 - 400

25. Clutch spring heavy 360 - 400
Place two springs face to face,
then add two more springs one

on each side, making a set of

4 springs. Use 18 springs, ma-

king 4

1/2

sets. Twenty springs

may be used -

5

sets - for more

spring pressure.

Place two springs face to face,
then add two more springs one

on each side, making a set of

4 springs. Use 18 springs, ma-

1/2

king 4
may be used -
spring pressure.

sets. Twenty springs

5

sets - for more

Square Barrel Engine Manual Service Manual

26. Clutch spring light 501 and
early oval barrel 250 and 360.

Take two springs face to face
for set of 2. Use 20 springs,
making 10 sets of 2 springs •

Late model 400 and 501

clutches that are the light
weight model uses 18 springs
stacked as shown above.

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27. This picture shows the proper
sequence of assembly for the all
steel clutch. It is recommended t,
use 20 springs when reassembling.

For 250, )60 and early 400 only.

One fiber plate.

Thickness new ~
Thickness replace ~

Thickness new ~
Thickness replace .080

Thickness new ~
Thickness replace ~

Note: When all fiber clutch is used

this plate will have no wear.
Check for flatness.

Driven plate

Driving plate

6 required.

6 required.

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:LUTCHES

27a. 250&360 fiber clutch

5 fiber plates ~ steel plates

18 to 20 springs double

~7b. 250

&

~OO steel clutch.

20 springs double

~OO&501 big clutch
First design big clutch

used in most 1971 ~OOcc

mote crossers.

6 steel slpined plates
7 fiber plates

1 terminal plate - Snap
ring it into terminal
plate groove.

~7c•

:ote: Clutch body (center of

clutch that is slpined)

is longer on 1st. design
clutch than 2nd design.
This clutch uses 20

_ sprin.ss stacked single

()()()()()()()(),i ()

-

-

Note: The clutch plates

- shall be installed to
throw the oil out.

:LUTCHES

27a. 250&360 fiber clutch

5 fiber plates ~ steel plates

Square Barrel Engine Manual Service Manual

18 to 20 springs double

~7b. 250

&

~OO steel clutch.

20 springs double

~OO&501 big clutch

~7c•

First design big clutch

-

-

_ sprin.ss stacked single

Note: The clutch plates

- shall be installed to

used in most 1971 ~OOcc

mote crossers.

6 steel slpined plates
7 fiber plates

1 terminal plate - Snap
ring it into terminal
plate groove.

:ote: Clutch body (center of

clutch that is slpined)
is longer on 1st. design

clutch than 2nd design.
This clutch uses 20

()()()()()()()(),i ()

throw the oil out.

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27d. Second design bip,

clutch used in all
1972 400

&

SOlcc models.

S steel splined plates
6 fiber plates
1 terminal plate. The
narrow machined ring

goes outside. The wide
machined band p,oes

inside.

Note: This clutch body (center

of clutch that is splined)
is shorter than the

lst-

design-

This clutch uses 18
springs stacked single

()()()()()()()()()

Note the heavy washer between
the inner

&

outer clutch bodies.

The spacer ring not shown
may go either on top or
under the spring washers.

Square Barrel Engine Manual Service Manual

27d. Second design bip,

clutch used in all
1972 400

S steel splined plates
6 fiber plates
1 terminal plate. The
narrow machined ring

goes outside. The wide
machined band p,oes

inside.

Note: This clutch body (center

of clutch that is splined)
is shorter than the

design-

This clutch uses 18
springs stacked single

()()()()()()()()()

&

SOlcc models.

lst-

Note the heavy washer between
the inner

&

outer clutch bodies.

The spacer ring not shown
may go either on top or
under the spring washers.

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Note:

The clutch throwout
bearing requires 14
ball bearin~s on all

models.

Note: The clutch nut must be

installed with "Loctite".
If the clutch nut comes

loose two ~ears will

engage at the same time.

NOTES TYP!CAL TO ALL CLUTCP.ES

Note: The clutch ?lates shall

be installed to throw
the oil out.

Note:

The clutch throwout
bearing requires 14
ball bearin~s on all
models.

Note: The clutch nut must be

installed with "Loctite".
If the clutch nut comes

loose two ~ears will

engage at the same time.

Note:

The clutch throwout
bearing requires 14
ball bearin~s on all

models.

Note: The clutch nut must be

installed with "Loctite".
If the clutch nut comes

loose two ~ears will
engage at the same time.

27e.

This is the engine
flywheel used on the

501 only.

NOTES TYP!CAL TO ALL CLUTCP.ES

Note: The clutch ?lates shall

Note:

Note: The clutch nut must be

be installed to throw
the oil out.

The clutch throwout
bearing requires 14
ball bearin~s on all
models.

installed with "Loctite".
If the clutch nut comes

loose two ~ears will
engage at the same time.

Square Barrel Engine Manual Service Manual

27e.

This is the engine
flywheel used on the

501 only.

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Square Barrel Engine Manual Service Manual

28. Remove the lock tab from the
clutch guide nut by lifting out.

The lock tab is reuseable.
Shown is a new lock tab and one
properly bent to secure the nut.

Not used in 501.

Use Loctite on the 501
clutch nut.

NOTE.

If the clutch nut comes loose
the transmission will engage
two gears at once.

29. Remove clutch center - special
clutch holding tool and 17mm
socket .

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Note: Removing the clutch center

without the Special clutch
tool can cause damage. This

damage will cause the clutch
plates to bind up and the
clutch will slip or not
properly release.

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Square Barrel Engine Manual Service Manual

30. Pull clutch center from clutch
case, remove bronze bush.

Remove clutch case an~ primary
chain and clutch thrust washer.
Note condition, if bent or

grooved replace washer.

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501cc not shown

reassembling, grease
side of engine sprocket

Do not g2ease lock washer.

Note the pin that keeps the
flywheels from rotating. The
pin is inserted between the con
rod and the engine cases.

2. Keep the flywheels from rotating
by inserting pin between connect-

ing rod and case. Remove engine
sprocket nut and lock washer,
pull sprocket, and spacer.

Tools, 3/8" pin, large screw
driver and 24mm wrench.

Note: When

back

nut.

1. Remove sprocket nut

2. Remove external flywheel
and the spacer ring.

32. Engine sprocket

1. 250-400cc

Remove lock tab

from engine sprocket nut -
chizel and hammer.

501cc not shown

reassembling, grease
side of engine sprocket

Do not g2ease lock washer.

Note the pin that keeps the
flywheels from rotating. The
pin is inserted between the con
rod and the engine cases.

2. Keep the flywheels from rotating
by inserting pin between connect-

ing rod and case. Remove engine
sprocket nut and lock washer,
pull sprocket, and spacer.

Tools, 3/8" pin, large screw
driver and 24mm wrench.

Note: When

back

nut.

1. Remove sprocket nut

2. Remove external flywheel
and the spacer ring.

32. Engine sprocket

1. 250-400cc

Remove lock tab

from engine sprocket nut -
chizel and hammer.

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Square Barrel Engine Manual Service Manual

)). Remove lock tab, shift linkage

cover plate, and shift linkage

pull rod. 10mm wrench, chisel
and hammer. See Misc. section
for proper indexing of shift

mechanism when reassembling.

34. Remove kick starter shaft and
spring

by

winding spring and

lifting straight up.

35. 250 and 360 models have eight
internal case screws. Large

blade screw driver.

)6. Late model 250, all 400's

and 501's have seven internal
case screws and one external.
Large blade screw driver.

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-

37. Remove spring from hook rachet

-

needle nose pliers.

38.

Remove left hand case - by hand
and.rawhide hammer.

39. Remove crank shaft assembly -
by hand.

40. Check flywheel alignment by ro-
tating on knife edges. Max. mis-
alignment is .002 inch at the end
of the magneto shaft, re-align

if

necessary. This must be done by

a motorcycle shop or a machine shop.

NOTE. It is suggested to reassemble the flywheels using

Loctite grade

35

and Loctite primer grade T. To

disassemble loctited flywheels heat to 450-500

0

F

in an~. Do not use a torch.

Square Barrel Engine Manual Service Manual

37. Remove spring from hook rachet
needle nose pliers.

38.

Remove left hand case - by hand

and.rawhide hammer.

39. Remove crank shaft assembly -
by hand.

NOTE. It is suggested to reassemble the flywheels using

Loctite grade

disassemble loctited flywheels heat to 450-500

in an~. Do not use a torch.

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40. Check flywheel alignment by ro-
tating on knife edges. Max. mis-
alignment is .002 inch at the end
of the magneto shaft, re-align

35

necessary. This must be done by

a motorcycle shop or a machine shop.

and Loctite primer grade T. To

if

0

F

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41. The connecting rod side play shall
be .019 - .020 inch when new. A
feeler gauge may replace the dial

indicator. The thickness of the
big end of the connecting rod when
new is .665 to .670 inch. It

is permissable to have more than

.020 if the connecting rod has
worn into the flywheel surface.

42.

The reference distance across the

flywheels is 2.475 - 2.490 inches.
This dimension should be used as
a reference only as the measure-
ment of the side clearance of the
rod is the only accurate method.

43. Remove shifting fork spindle by

hand. Check to see that it is

not bent.

44. Remove gear stack - by hand.
Note the shims. Some trans-
missions do not have shims.
The shims control the 1st.
gear tolerance to

o.

3mm

(.012). If the transmission

is improperly shimmed it is

possible to engage two gears

at once.

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45. Remove main shaft and shifting

Square Barrel Engine Manual Service Manual

fork from lower scroll - by hand.

Grind here

.030 inch Hax.

46. Remove lay shaft and shifting fork
from upper scroll. CHECK to see if

the shifting fork on the lay shaft

is not touching second gear on the

main shaft. If"it is touching,
grind for clearance.

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47. Gear stack showing the positio-
ning of the shifting forks.

48.

When fitting a new 1st gear to
the lay shaft be sure it has the

same amount of internal clearance
(slop) as the 3rd gear on the lay

shaft.

Close

Ratio

1

2

3

4

Main

17 20

22 22

Teeth

Lay

20

18 16

13

Teeth

1.99

1.52 1.23

1.0

Ratio

to 1

Wide

Ratio

1

2 3

4

Main

14 18 21

*

Teeth

Lay

23 19

,~

1:

Teeth

2.78

1.79 1.29 1.0

Ratio

Primary Ratio

19/39=1.86 to 1

*Close Ratio ~ears are used

in the

wide ratio

transmission at

these locations

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Replacing "0" rings on shifting

.

53.

Replacing "0" rings on shifting
cam spindle.

54.

Remove engine seals and reinstall.
Cases must be heated approx. 250

0

.

Use an oven or hot plate. Use of
a torch is not recommended.

the main bearings.

53.

cam spindle.

Remove engine seals and reinstall.

54.

Cases must be heated approx. 250
Use an oven or hot plate. Use of

a torch is not recommended.

Square Barrel Engine Manual Service Manual

0

55. Cases must be heated approx.

0

r

250
The screw drivers are pointing to
the bearing locations.

Crank shaft
Remove bearing race by locally
heating race red and wedging a
sharp chisel behind the race. Tap
chisel li~tlY with hammer. The

race may removed with a blade
puller once it has moved. It is

suggested that the local motor-

cycle shop performes this operation.
The seal land must be checked for
any roughness caused by race removal.

for removal of any bearing.

5"-. 501 engine seals

are external to

56.

The engine is now torn down far

enough for major servicing. Do

not d~sassemble any further un-

less absolutly necessary.

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57.

Removing the felt wick and re-
taining spring.

58.

Removing the circlip from the
shifting pawl.

59.

Removing the shifting pawl.

60. Removing the pawl spring.

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TECHNICAL

TECHNICAL

SECTION

Square Barrel Engine Manual Service Manual

SECTION

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Square Barrel Engine Manual Service Manual

61. Shift earn bush and shift pawl

61. Shift earn bush and shift pawl
stud are not normally removed,

however, if worn, they are

available from Maieo parts dis-

tributor.

62. Fuel tap assy

63.

Ignition point assy

stud are not normally removed,
however, if worn, they are
available from Maieo parts dis-
tributor.

62. Fuel tap assy

63.

Ignition point assy

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64.

Carb adaptors, and air cleaner
assy.

65.

Foot starter assembly

66. Ignition side assembly showing
engine seal, roller bearing, and
oil seal.

501 engine seals are external
to the main bearings.

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Square Barrel Engine Manual Service Manual

.7, Drive side assembly showing seal

67.

and ball bearing,

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68 TECHNICAL DATA

Engine: Ignition:

360cc

SOlce

12:1

Two-stroke. single

-:::isplacement:

Compression ratio:

ruel:

Lubrication:

cylinder engine

250cc ~OOcc

247cc 386cc

12,3:1 12:1

Regular petrol

Petroleum type racing oil,
e.g. Castrol GP 50 wt. mixing
ratio of

20:1 (5\)

Appt. magneto separate high-tension coil.
Timing: 250=2.98TDC, 400=3.6 BTDC,

501=3.6 BTDC
Contact breaker gap: .014-.018"(0.35-0.45)
Spark plug: Champion L3G=250, L2G=400,

N2G=501

Frame:

Power transmission:

Oil-damped telescopic fork. 7 inches
movement. Oil capacity: 60z (0.2 litre)

per fork leg. Oil recommendation: Engine
oil SAE 20-50 depending on temperature,
rider and course.

Frame

is

welded chromemolybdenum steel.

Pivoting rear arm in rubber bushings.

front: 3.0OX 21" with moto •.cross tyre.
Rear: 4.0OxlS" with moto-cross tyre for 250

4.SOX18" with moto-cross tyre for 400&501

Wheels:

Front fork:

400 - l3T

front -

52!

rear

250 -

11T

front

- 52T

rear

501 -

l3T

front -

52T

rear

400 -

l3T front - 59T

rear

250 -

11T

front

-

59T

rear

501 -

l3T front

-

59T

rear

;earbox:

Seven disc mote-cross type clutch.

Primary transmission

by

dual row primary

chain 19T x

39r

(1.86 to 1)

-Secondary transmission

by

chain drive

5/8"

x

114

ft

).

12 teeth on gearbox sprocket

]nd 53 teeth on rear wheel.

"SII

Transmission

T" Transmission

Transmission

4-Speed Heavy Duty

"Til

"S"

Brakes:

1st

2nd
3rd
4th

Mota Cross

1.99 to 1

1. 52

1. 23

1.0

Cross Country

2.78

to

1

1.79

1.29

1.0

rear: diam. 160x30 mm (6 5/16

11

xl 3/16")

front: diam. 14Ox30 mm (5 1/2"xl 3/16")

Saddle:

Oil

capacity:

1

quart

-;11

recommendation: Transmission oil SAE 40wt.

for

2S0, SAE 90wt.

gear

oil for 400

&

501.

Moto-cross type.

Footrests:

FOlding footrests at a 45° angle.

;arhurettor: 250 400

501

Moto-eross type with paper element.

~ir filter:

listen

&

Flywheel data:

Wheelbase: 54" (1315

1mI)

Saddle height: 31.5" (SOO

rrrn)

Ground clearance: 7" (180 mm)
Dry weight: 250cc: 102 kg (224 lb.)

400cC: 105 kg (231 lb.)
50lcc: 107 kg (239 lb.)

Fiberglass fuel tank

Capacity: 7 liter (1.9 Gals)

rueltank:

Dimensions:

180

35

280

3

1 1/2

185

35

285

3

1 1/2

1/36/101

180

35

280

3

1 1/2

Jing:
Main jet:

.dling jet:
leedle jet:
leedle position:

Air screw opening:

Flywheel assembly. Side play of connecting

-rod shall be .019-.020. Replace .023 or
;reater.
listance across flywheels outside to outside

2.475. Reference only.

Run out when

supported on bearing area ,

-leasured at extreme end of magneto taper
.hall not exceed .002 inch •

•'iming side bearing - up

&

down play .010

inch max.

~iston ring end gap - .003 per inch of

iameter.

~ylinder sleeve to cylinder new .013
interference when replacing turn sleeve

-.0 -

.004-.006 interference.

iston to cylinder clearance .002 inch

or 250

&

400. 501 shall be .0025 inch.

Screwed joints:

Nut for magneto: 10 lb.ft. (1.7kpm)
Nut for output chainsprocket:50 Ib.ft.(7kpm)
Nuts which hold the cylinder head to the
cylinder: 15 lb.ft.(2.5kpm) for 250

&

400;

25 lb.ft. 13.5kpm) for 501

Engine mounting bolts:25 lb.ft.{3.Skpm) Bmm bolts
35 lb.ft. (5.2kpm) for 10m bolts
Nuts which hold the bearing bolts for the rear

wheel

pivot arm: 25 Ib.ft. (3.5kpm)
Clutch nut • 30 foot lbs.
Engine sprocket nut. 35-45 foot Ibs.

Counter shaft nut - 40-50 foot lbs.

68 TECHNICAL DATA

Engine: Ignition:

360cc

SOlce

12:1

Two-stroke. single

-:::isplacement:

Compression ratio:

ruel:

Lubrication:

cylinder engine

250cc ~OOcc

247cc 386cc

12,3:1 12:1

Regular petrol

Petroleum type racing oil,
e.g. Castrol GP 50 wt. mixing
ratio of

20:1 (5\)

Appt. magneto separate high-tension coil.
Timing: 250=2.98TDC, 400=3.6 BTDC,

501=3.6 BTDC

Contact breaker gap: .014-.018"(0.35-0.45)

Spark plug: Champion L3G=250, L2G=400,

N2G=501

Frame:

Power transmission:

Oil-damped telescopic fork. 7 inches
movement. Oil capacity: 60z (0.2 litre)

per fork leg. Oil recommendation: Engine
oil SAE 20-50 depending on temperature,
rider and course.

Frame

is

welded chromemolybdenum steel.

Pivoting rear arm in rubber bushings.

front: 3.0OX 21" with moto •.cross tyre.

Rear: 4.0OxlS" with moto-cross tyre for 250

4.SOX18" with moto-cross tyre for 400&501

Wheels:

Front fork:

400 - l3T

front -

52!

rear

250 -

11T

front

- 52T

rear

501 -

l3T

front -

52T

rear

400 -

l3T front - 59T

rear

250 -

11T

front

-

59T

rear

501 -

l3T front

-

59T

rear

;earbox:

Seven disc mote-cross type clutch.

Primary transmission

by

dual row primary

chain 19T x

39r

(1.86 to 1)

-Secondary transmission

by

chain drive

5/8"

x

114

ft

).

12 teeth on gearbox sprocket

]nd 53 teeth on rear wheel.

"SII

Transmission

T" Transmission

Transmission

4-Speed Heavy Duty

"Til

"S"

Brakes:

1st

2nd
3rd
4th

Mota Cross

1.99 to 1

1. 52

1. 23

1.0

Cross Country

2.78

to

1

1.79

1.29

1.0

rear: diam. 160x30 mm (6 5/16

11

xl 3/16")

front: diam. 14Ox30 mm (5 1/2"xl 3/16")

Saddle:

Oil

capacity:

1

quart

-;11

recommendation: Transmission oil SAE 40wt.

for

2S0, SAE 90wt.

gear

oil for 400

&

501.

Moto-cross type.

Footrests:

FOlding footrests at a 45° angle.

;arhurettor: 250 400

501

Moto-eross type with paper element.

~ir filter:

listen

&

Flywheel data:

Wheelbase: 54" (1315

1mI)

Saddle height: 31.5" (SOO

rrrn)

Ground clearance: 7" (180 mm)
Dry weight: 250cc: 102 kg (224 lb.)

400cC: 105 kg (231 lb.)
50lcc: 107 kg (239 lb.)

Fiberglass fuel tank

Capacity: 7 liter (1.9 Gals)

rueltank:

Dimensions:

180

35

280

3

1 1/2

185

35

285

3

1 1/2

1/36/101

180

35

280

3

1 1/2

Jing:
Main jet:

.dling jet:
leedle jet:
leedle position:

Air screw opening:

Flywheel assembly. Side play of connecting

-rod shall be .019-.020. Replace .023 or
;reater.
listance across flywheels outside to outside

2.475. Reference only.

Run out when

supported on bearing area ,

-leasured at extreme end of magneto taper
.hall not exceed .002 inch •

•'iming side bearing - up

&

down play .010

inch max.

~iston ring end gap - .003 per inch of

iameter.

~ylinder sleeve to cylinder new .013
interference when replacing turn sleeve

-.0 -

.004-.006 interference.

iston to cylinder clearance .002 inch

or 250

&

400. 501 shall be .0025 inch.

Screwed joints:

Nut for magneto: 10 lb.ft. (1.7kpm)
Nut for output chainsprocket:50 Ib.ft.(7kpm)
Nuts which hold the cylinder head to the
cylinder: 15 lb.ft.(2.5kpm) for 250

&

400;

25 lb.ft. 13.5kpm) for 501

Engine mounting bolts:25 lb.ft.{3.Skpm) Bmm bolts
35 lb.ft. (5.2kpm) for 10m bolts
Nuts which hold the bearing bolts for the rear

wheel

pivot arm: 25 Ib.ft. (3.5kpm)
Clutch nut • 30 foot lbs.
Engine sprocket nut. 35-45 foot Ibs.

Counter shaft nut - 40-50 foot lbs.

Square Barrel Engine Manual Service Manual

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