Briggs & Stratton 270962 Counterbalance Systems, Synchro-BalanceSystem, Disassemble, Inspect

COUNTERBALANCE SYSTEMS

Two styles of counterbalance systems are used on Vertical crankshaft engines.

Models 280000 and 310000 (built before July 2001) have the Synchro-Balance® system. Models 280000 and 310000 built July 2001 and later, and all models 210000 and 330000 have the AVS® system. Both systems use a counterweight that oscillates opposite the direction of the piston, to reduce engine vibration (Figure 25).

Disassemble

1. Remove crankshaft gear (A, Figure 26). NOTE: If gear is tight, pry it off using two screwdrivers being careful not to damage gear.

2.Woodruff key (B) can be removed, if required.

3.Remove screw (A, Figure 27) from counterweight.

4.Remove PTO counterweight (B), dowel pin (C), and link (D) from crankshaft.

5.Remove crankshaft from magneto counterweight (E).

Figure 25

Synchro-Balance® System

Remove Counterbalance System

1.Remove blower housing, flywheel, cylinder head, and sump. Discard gaskets.

2.Remove connecting rod and piston assembly.

3.Remove crankshaft and counterweight assembly.

Figure 27

Inspect

1.Visually inspect counterweight bearings for scoring or discoloration. If found, replace both counterweights as a set.

2.Measure the counterweight bearing diameters and compare to the values shown in Section 12 - Engine Specifications. If either bearing is worn beyond the reject dimensions, replace both counterweights as a set.

3.Measure the crankshaft eccentric diameters and compare to the values shown in Section 12 - Engine Specifications.

4.If crankshaft eccentrics are worn, scored, or discolored, replace the crankshaft.

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Figure 26

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