Briggs & Stratton 273521, 271172, 270962 Inspect Cylinder, Reconditioning Bore, Resizing Bore

CYLINDER

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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 1). If mounting surfaces are distorted more than 0.004” (0.1 mm), the cylinder must be replaced.

Figure 1

2.Check cylinder bore for wear using Telescoping Gauge #19485 and Dial Caliper #19199.

Figure 2

Measure twice (90° apart) at the top, center, and bottom of the piston ring travel (Figure 2).

Compare measurements to the standard cylinder bore sizes provided in Section 12 - Engine Specifications.

If the cylinder bore is more than 0.003” (0.08

mm)oversize, or 0.0015” (.04 mm) out of round, it must be resized.

Reconditioning Bore

If cylinder bore is within specification and shows no signs of scoring or other damage, it can be reconditioned using a rigid hone with finishing stones to restore the proper crosshatch angle. The correct crosshatch of approximately 45° (Figure 3) ensures proper lubrication and piston ring break-in.

Figure 3

NOTE: IT IS MOST IMPORTANT THAT THE ENTIRE CYLINDER BE THOROUGHLY CLEANED AFTER HONING.

Resizing Bore

Always resize to exactly .020” (.51 mm) larger than standard bore size. Done accurately, the service oversize rings and pistons will fit perfectly with proper clearances.

Cylinders can be quickly resized with Hone #19205 or #1921. Use the stones and lubrication recommended by the hone manufacturer to produce the sizing and finish.

NOTE: IT IS MOST IMPORTANT THAT THE ENTIRE CYLINDER BE THOROUGHLY CLEANED AFTER HONING.

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