Engine Overhaul; Check Cylinder; Section 4 Engine Overhaul - Briggs & Stratton 272147 Repair Manual

TM
Vanguard Twin-Cylinder OHV Liquid-Cooled Engine
Section 4 - Engine Overhaul
SECTION 4

ENGINE OVERHAUL

CHECK CYLINDER

Check cylinder for cracks or stripped threads. Check
cylinder bores for damage or scoring.
1. Check cylinder head mounting surface for
distortion with a straight edge, Fig. 64.
If mounting surfaces are distorted more than .004" (0.1
mm), the cylinder must be replaced.
Fig. 64
2. Check cylinder bores for wear using telescoping
gauge, Tool
#19404
Standard Bore Size:
3.189" - 3.190"
(81.00 - 81.02 mm)
a. Measure cylinder bore in 6 points at right
angles as shown, Fig. 65.
and dial caliper, Tool
#19199
b. If cylinder bore is worn more than .003" (0.076
mm) or more than .0015" (0.038 mm) out of
round, it must be resized.
VECTOR
CENTER OF PISTON RING TRAVEL
Fig. 65
NOTE
: If cylinder bores are within specification
and show no signs of scoring or other damage,
new piston rings may be installed providing the
cylinder bores are reconditioned using a rigid
hone with finishing stones, to restore the proper
cross hatch angle in the cylinder bores. The
proper cylinder crosshatch ensures proper
lubrication and piston ring break in. Refer to
Page 3, "Cylinder Finish" (Cross Hatch) for
correct procedure for installing crosshatch.
Resizing
.
Always resize to exactly .020" (.51 mm) standard bore
size. If this is done accurately, the service oversize rings
and pistons will fit perfectly and proper clearances will be
maintained.
Cylinders can be quickly resized with a good hone such
as Briggs & Stratton Tool
Stratton source of supply. Use the stones and lubrication
recommended by the hone manufacturers to produce the
correct cylinder cross hatch.
NOTE
: Automatic transmission fluid is
acceptable honing oil. Another acceptable
honing oil can be made by mixing 4 parts No. 30
weight oil with 1 part kerosene.
If a boring bar is used, a hone must be used after the
boring operation to produce the proper cylinder cross
hatch.
TOP
CENTER
BOTTOM
MEASURE AT SIX POINTS
. Contact your Briggs &
#19205
Page 35