This WSM powerhead rebuild kit covers the Mercury and Mariner 4-cylinder 40, 45, and 50 HP applications listed below. It uses the 2.565-inch crossflow bore family and includes the pistons, gasket set, crank bearings, rod bearings, and rod bolts for the rebuild.
Fitment
- Mercury/Mariner 50 HP 4-cylinder crossflow: 1970-1985
- Mercury/Mariner 45 HP 4-cylinder crossflow: 1986-1989
- Mercury/Mariner 40 HP 4-cylinder crossflow: 1990-1997
Technical Specifications
- WSM standard-size kit: 100-05-10
- 4-cylinder crossflow powerhead
- 2.565-inch standard bore
Piston Size Options
- Standard
- .010 oversize
- .015 oversize
- .020 oversize
- .030 oversize
- .040 oversize
Measure the finished cylinder bore before selecting piston size.
Complete Kit Includes
- 4 WSM piston kits with rings, wrist pins, and clips
- Complete gasket kit: 1 head gasket, 1 late-style head gasket, 1 base gasket, 1 adapter-plate gasket, 2 carburetor gaskets, 2 transfer-port gaskets, 1 water-tube gasket, 2 exhaust gaskets, 3 O-rings, and 3 seals
- 1 upper, 1 center, and 1 lower main bearing
- 4 upper and 4 lower connecting-rod bearings
- 8 connecting-rod bolts
Fitment Note
Outboard applications can vary by horsepower, year, bore size, rod-guidance style, and model or serial range. Compare the fitment and technical details above with your engine before ordering.
Questions About This Product?
Have questions about this product? Email us at customerservice@marinepartswarehouse.com and include your motor information with your question.
