Maico SQUARE BARREL User manual

SQUARE BARREL
ENGINE SECTION
NOTE: ALL THREADS ARE RIGHT HAND
(Clockwise to tighten - counter
clockwise to loosen).
SQUARE BARREL
ENGINE SECTION
NOTE: ALL THREADS ARE RIGHT HAND
(Clockwise to tighten - counter
clockwise to loosen).
MAICO
Service Manual
Square Barrel Engine Manual Service Manual
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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.
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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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.
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.
15. Remove cylinder head - 13mm
socket.
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Square Barrel Engine Manual Service Manual

16. Remove cylinder
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.
20. The piston rings shall be check-
ed for end gap. A new ring has
.010 inch end gap. When end gap
exceeds
.016 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
180
0
so that
transmission oil will not run
out. Having the motorcycle
level will greatly assist
when replacing the clutch springs.
22. Remove the clutch snap rings
with special puller and two
small blade screw drivers.
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Square Barrel Engine Manual Service Manual

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23. Remove by hand the clutch plates,
clutch guide, and note direction
of fiber plate and spring stack
up.
2~. Clutch spring height
new .075 - replace .070
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Square Barrel Engine Manual Service Manual

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.
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.
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.
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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Square Barrel Engine Manual Service Manual