Generac Power Systems 53187 - Manual (Page 75)

SECTION 2.4
DISASSEMBLY AND INSPECTION
1
PART 2
ENGINE MECHANICAL
Pistons and Piston Rings (Continued)
If the cylinder Is oversized, use an oversized piston
ring set.
□ Standard Piston Ring Set Is Part No. 211-70939
□ 0.5mm O.S. Rings, Part No. 212-70939
□ 1.0mm O.S. Rings, Part No. 213-70939
W hen installing the Piston Rings, instail them as
show n in Figure 19.
ROD BUSHING TO PISTON PIN CLEARANCE;
Measure the inside diam eter of the connecting rod
sm all end bushing. Also, m easure the piston pin. Cal­
culate the pin to bushing clearance. It clearance ex­
ceeds allow able lim its, repiace the connecting rod.
□ standard Clearance = 0.0006-0.001 inch (0.015-
0.03mm)
□ Allowable Limit = 0.003 inch (0.08mm)
ROD TO CRANKPIN CLEARANCE:
Assem ble the connecting rod to the crankshaft and
m easure the play in the shaft direction. If play is greater
than ailow able lim it, replace the connecting rod.
□ Standard Play = 0.004-0.012 inch (0.1-0.3mm)
□ Allowable Limit = 0.028 inch (0.7mm)
CONNECTING ROD BEARING;
Inspect the connecting rod bearing for peeiing,
cracks, etc. Replace, if defective. Use ‘i^astigauge' to
check bearing oil clearance as follow s;
1. Rem ove oil and dirt from rod bearing and from
crankpin.
2. Cut a iength of plastigauge to the sam e length as the
w idth of the bearing. Place It on the crankpin, parallel
w ith the crankshaft. DO NOT PLACE OVER AN OIL
HOLE. See Rgure21.
3. Assem ble the connecting rod bearing and cap to the
crankpin. Tighten to 22-25 foot-pounds (3.0-3.5 m -kg).
Connecting Rods
CHECK BENDING, PARALLELISM, DAM AGE;
Use a connecting rod alignm ent tool to check the
connecting rod for bending and parallelism . If allow able
lim its are exceeded, replace the connecting rod.
CAUTION: DO NOT rotate the connecting rod or
crankshaft while plastigauge Is Installed.______
4. Rem ove the connecting rod and bearing. Use the
plastigauge scale to m easure the oil clearance. Be sure
to m easure the w idest area of the plastigauge.
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