Briggs & Stratton 030430, Руководство по обслуживанию и ремонту

Страница: 43 / 76

43
Cylinders, Covers and Sumps
Inspect Cylinder
1. Visually check cylinder for cracks, stripped threads, and
bore damage.
• If cracks are found, replace the cylinder.
• Stripped threads can sometimes be repaired using
a helicoil, but if multiple holes have thread damage,
replace the cylinder.
• Bore damage, if not severe, may be corrected by
reconditioning or resizing (see below).
Check cylinder head mounting surface for distortion with a
straight edge (Figure 56). If mounting surfaces are distorted
more than 0.004 in. (0.1 mm), the cylinder must be replaced.
Figure 56
2. Check cylinder bore for war using Telescoping Gauge
#19485 and Dial Caliper #19199.
Figure 57
Measure twice (90° apart) at the top, center, and bottom of
the piston ring travel (Figure 57).
Compare measurements to the standard cylinder bore sizes
provided in
Engine Specifi cations .
If the cylinder bore is more than 0.003 in. (0.08 mm)
oversize, or 0.0015 in. (0.04 mm) out of round, it must be
resized.
Reconditioning Bore
If cylinder bore is within specifi cations and shows no signs
of scoring or other damage, it can be reconditioned us-
ing a rigid hone with fi nishing stones to restore the proper
crosshatch angle. The correct crosshatch of approximately
45° (Figure 58) ensures proper lubrication and piston ring
break-in.
Figure 58
NOTICE: IT IS MOST IMPORTANT THAT THE ENTIRE
CYLINDER BE THOROUGHLY CLEANED AFTER HONING.
Resizing Bore
Always resize to exactly 0.020 in. (0.51 mm) larger than
standard bore size. Done accurately, the service oversize
rings and pistons will fi t perfectly with proper clearances.
Cylinder can be quickly resized with Hone #19205 or #19201.
Use the stones and lubrication recommended by the hone
manufacturer to reproduce the sizing and fi nish.
45°