Cylinder Finish (Cross Hatch); Cleaning; Main Bearings - Briggs & Stratton Twin Cylinder L-Head Repair Manual

Honing is done with a variable speed 1/2", portable drill
and a honing fixture. See page 8 for dimensions to
make your own honing fixture.
Check cylinder bores at top and bottom for burrs.
Remove burrs to prevent damage to hone.
Use four (4) 2-1/2" long, 3/8"–16 UNC hex head screws
with 3/8" flat washers and fasten cylinder to honing
fixture, Fig. 2.
1. Clamp honing fixture and cylinder securely in a
vise at a convenient work height. Place hone drive
shaft in chuck of portable drill and tighten.
2. Cut a wood block and place inside cylinder to
prevent hone from extending further than 3/4"
(19.0 mm) to 1" (25.0 mm) below cylinder bore.
3. Place hone in middle of cylinder bore.
4. Tighten adjusting knob until stones fit snugly
against cylinder wall. DO NOT FORCE.
5. Connect drive shaft to hone. Be sure that cylinder
and hone are centered and aligned with drive shaft
and drill spindle.
6. Lubricate hone as recommended by hone
manufacturer. The recommended drill speed is
300 to 700 RPM MAXIMUM and 40-60 strokes per
minute. Because cylinder bores normally wear
only in the area of ring travel, the cylinder bore will
be round above and below ring travel, Fig. 3.
7. Start drill and, as hone spins, move it up and down
at the bottom of the cylinder bore. Gradually in-
crease the length of the strokes until hone travels
full length of cylinder bore, Fig. 3. Lubricate hone
frequently to prevent build up on stones.
Be sure that hone does not extend more than 3/4" to 1"
from top or bottom of cylinder or stones may be
damaged.
As cutting tension decreases, stop hone and tighten
adjusting knob following hone manufacturers recom-
mendations. Check cylinder bore frequently with a
micrometer or dial caliper, Tool #19199, and telescop-
ing gauge, Tool #19198.
NOTE: On cast iron sleeve cylinders, Model
Series 400400, 400700, 402400, 402700,
404400, 404700,
462770 change from rough stones to
finishing stones, when within .0015" (.04
mm) of desired size. See Cylinder Finish
(Cross Hatch).

Cylinder Finish (Cross Hatch)

The finishing stones are used after the cylinder bore
has been resized to within .0015" (.04 mm) of the
desired size or when reconditioning a cylinder bore.
The finishing stones will produce the correct cross
hatch necessary for proper lubrication and piston ring
rotation. The correct cross hatch angle is approximate-
ly 45 degrees, Fig. 4.
It is recommended that the cylinder bores be recondi-
tioned to restore the cross hatch when new piston rings
are to be installed in a cylinder that is within specifica-
tion. Be careful not to hone oversize or it will be
necessary to resize the cylinder.
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Cleaning

It Is Most Important That The Entire Cylinder And
Crankcase Be Thoroughly Cleaned After Honing.
Honing grit is highly abrasive and will cause rapid wear
to all of the internal components of the engine unless it
is completely removed.
1. Wash the cylinder and crankcase carefully in a
2. Thoroughly wash cylinder and crankcase using a
3. Rinse thoroughly with hot running water. Repeat
422400, 422700,

MAIN BEARINGS

To meet different Original Equipment Manufacturers
application needs, Briggs & Stratton twin cylinder
engines have been built using three types of main
bearings:
1. Ball Bearing
2. Plain Bearing
3. DU Bearing
10
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Fig. 4 – Cross Hatch
solvent such as kerosene or commercial solvent.
stiff brush with soap and hot water.
washing and rinsing until all traces of honing grit
are gone.
NOTE: When cylinder and crankcase have been
thoroughly cleaned, use a clean white rag
or napkin and firmly wipe the cylinder bore.
If honing grit is present it will appear as a
gray residue on rag. If any honing grit is
evident, re-wash and rinse entire cylinder
and crankcase and check again. When
there is no trace of honing grit on rag, the
cylinder is properly cleaned. On cast iron
bore models, oil the cylinder bore to
prevent rusting.
NOTE: See Sec. 11 for ball bearing removal and
installation.
45°
3