Briggs & Stratton 250000 Specifiche Scaricare il pdf (Pagina 320)

NOTE: SPECIFICATION TABLES BEGIN ON PAGE 10 OF THIS SECTION.

INSPECTION

All Models

Always inspect the cylinder after engine disassembly.

Visual inspection will show cracks, stripped bolt holes,

broken fins or cylinder wall damage.

Use Telescoping Gauge (4), Tool #19404, shown in the

middle (2) position, Fig. 1, with a dial caliper, or use an

inside micrometer to measure bore size at right angles

to cylinder bore.

TABLE NO. 1, Specifications, lists the standard bore

sizes.

Measure the cylinder bore at right angles at each of

three locations. Measure at the top (1), middle (2) and

bottom (3) of piston ring travel.

If the bore is more than .003” (.08 mm) oversize, or

.002” (.04 mm) out of round on cast iron cylinders, or

.003” (.06 mm) out of round on aluminum cylinders, it

must be resized, or see NOTE below.

Fig. 1

NOTE:Chrome ring sets are available for some engine models. See Service Bulletin #479 or Illustrated Parts List.

Chrome rings are used to control oil consumption in bores worn up to .005” (.13 mm) over standard. The

cylinder bore receiving chrome rings does not need glaze breaking or cross hatch. If glaze breaking or

installing of cross hatch is desired, the entire engine block must be thoroughly cleaned in hot water using

common dish soap or other commercially available soap.

To install a proper crosshatch, see “Cylinder Finish” on page 4.

NOTE:When installing new non-chrome

piston rings in a cylinder bore that is within specification, the bore should

be reconditioned. Correct cylinder cross hatch ensures proper ring lubrication and break-in. See ‘‘Cylinder

Finish,” page 4. Some engine models produced at the factory have diamond bored cylinders which do not

exhibit a cross hatch finish. The diamond bore cylinders are reconditioned

using the same procedure as a

conventional cylinder.

RESIZING CYLINDER BORE

ALWAYS RESIZE TO EXACTLY .010” (.25 mm), .020” (.51 mm), OR .030” (.76 mm) OVER STANDARD BORE SIZE

AS SHOWN IN TABLE NO. 1, SPECIFICATIONS. If this is done accurately, the stock oversize piston and rings will fit

correctly and proper clearances will be maintained. Cylinders, either cast iron or aluminum, can be accurately resized

with hone sets listed in TABLE NO. 8, Specifications.

Use stones and lubrication recommended by hone manufacturers for various cylinder bores to obtain proper cylinder

wall finish.

If a boring bar is used, a hone must be used after the boring operation to produce the correct cylinder wall finish.

Honing can be done with a portable electric drill, or a drill press.

1 2 ... 315 316 317 318 319 320 321 322 323 324 325 ... 337 338

Nessun commento

Briggs & Stratton 250000 Specifiche Pagina 320