Service Manual
ENGINE TOP END 4-21
0.25 mm Oversize: 76.25ll mm (3.0020 in)
Service Limit: 76.317 mm (3.0046 in)
0.5 mm Oversize:
Service Limit:
76.500 mm (3.0118 in)
76.567 mm (3.0144 In)
0.75 mm Oversize:
Servke Limit
76.750 mm (3.0217 in)
76.817 mm (3.0242 in)
Cylinder Bore Out-of-Round
Standard: 0.01 mm (0.0004 in)
Servke Limit: 0.056 mm (0.0022 in)
Cylinder Boring and Honing
Always resize to exactly ‘0.25 mm (0.01 in), or 0.5 mm (0.02 in), 0 75
mm (0.03 in) over the standard bore size.
If this is done accurately, the stock oversize rings and pistons will fit
perfectly and Iproper clearance will be maintained.
Resizin’g the cylinder balre can be done by reliable repair shop or by
using a drill press and honilng tool.
Use the stone recommended by the hone manufacturers to produce
correct cylinder wail finish.
Machine-bore first, the bore diameters should be shown in the table.
Change to a honing stone for finishing, the final bore diameter should
be as shown tin the table.
Be sure the correct stone is used and the stone is not worn.
@Clean the cylinder at the top and bottom of the cylinder to remove
burrs and pieces of the base and head gasket.
l
Anchor the cylider (block) on the drill press table before honing.
@Align the center of the cylinder bore to the press center. Set the press
to operate from 200 to 250 rpm.
@Connect the drive shaft to the hone and set the stop on the drill press
so the hone can only extend 20 to 25 mm (3/4 to 1 .O in) above the
top or below the bottom of the cylinder liner.
ORotate the adjusting nut (knob) on the hone until the stones conltact
snugly against the cylinder wall at the narrowest point. “Do not
Force.”
@Turn the stone by hand. If you cannot turn it, the stone is too tight.
Loosen the hone until it can be turned by hand.
@Be sure that the cylinder and hone are centered and aligned with the
drive shaft and drill spindle.
l
Pour honing oil inside aof the cylinder during the honing operation.
Start the drill press. Mlove the hone up and down in the cylinder
approximately 20 cyclesper-minute.
l
Check the diameter of the cylinder bore regularly during honing, using
an inside micrometer.
t
--
AQWTION
--
Stop the drill press before measuring and remove the hme from the
cylinder.
-- 3
NOTE
0 The .finish should not be smooth, but have a 40 to 60 degree
crosshatch pattern.
OHone the cylinder until it is about 0.007 to 0.009 mm (0.0003 to
0.0004 in) large to allow for shrinkage when the cylinder cools.
Fine Boring Bore Dlameter
Bore Diameter
--
76.230 to 76.210 mm
(3.0012 to 3.0004 in)
-~
76.480 to 76.460 mm
(3.0110 to 3.0102 in)
I
0.50 mm 76.730 to 76.710 mm
(3.0209 to 3.0201 in)
Final Bore Diameter
1 Oversize 1 Bore Diameter
I
0.25 mm 76.250 to 76.230 mm
(3.0020 to 3.0012 in)
I 0.5omm
I
0.50 mm
76.500 to 76.480 mm
(3.0118 to 3.0110 in)
--
76.750 to 76.730 mm
(3.0216 to 3.0209 in)