Standard size piston ring set for the Briggs & Stratton 656cc V-twin, replacing part number 499604. Bore is 2.970 inch, 75.44mm. One set contains three rings and covers one cylinder, so a V-twin engine requires two sets. Fits model numbers in the 40xxxx family including 4025A7, 4035A7, 4045A7, 403677, 404577, 405577, 405777, 406577, 406777, 407577, 407677, 407777 and 40G777. This engine went into riding mowers, zero turn mowers and lawn tractors from a number of equipment makers, so the model number stamped on the blower housing is what identifies it, not the machine. Horsepower alone does not identify the engine either. The 570cc 20 horsepower, the 480cc 16 horsepower and the 724cc 23 to 26 horsepower engines all take different ring sets, so check the six digit model number. Briggs lists 499606 as the .020 oversize set for a bored cylinder.
- FITS THE BRIGGS & STRATTON 656cc V-TWIN, model numbers beginning 4025A7, 4035A7, 4045A7, 403677, 404577, 405577, 405777, 406577, 406777, 407577, 407677, 407777 and 40G777. Replaces Briggs 499604. Bore is 2.970 inch, 75.44mm. This engine was fitted to riding mowers, zero turns and lawn tractors across many equipment makes, so identify it by the model number stamped on the blower housing rather than by the machine it came out of.
- ONE SET, ONE CYLINDER. Briggs packages 499604 as three rings, which is one piston's worth. A V-twin needs two sets to do the whole engine. Order both before you split the engine down.
- CHECK YOUR MODEL NUMBER, NOT THE HORSEPOWER. There is more than one 20 horsepower V-twin in this family. The 570cc engines, model numbers starting 350400, 351700 and 356400, use a completely different ring set. So does the 480cc 16 horsepower and the 724cc 23 to 26 horsepower. The six digit model number stamped on the blower housing is the only thing that settles it.
- STANDARD SIZE. This set is for a cylinder still at standard bore. Briggs lists 499606 as the .020 inch oversize set for the same engines. If your block has been bored, measure the finished bore and order to match.
- WHEN RINGS WILL FIX IT. Rings cure oil burning and crankcase blowby on a bore that is still round and within taper limits with visible crosshatch. On a bore that is scored or glazed hard they will not seal and the oil consumption returns within a season. Measure the bore, hone it before assembly, and stagger the ring gaps around the piston.