Engine Bearings
About Engine Bearings
Engine bearings let the crankshaft, connecting rods and other shafts turn with very little friction while they carry the loads of combustion. Riders replace them when they find play in the crank or hear noise from the bottom end, or when the engine is already apart for a rebuild and old bearings should not go back in.
The listings cover several kinds of bearing. Crankshaft and case bearings support the crank, piston pin and top end bearings sit in the rod, and roller sets, pinion shaft bearings and bushings are listed for Harley-Davidson Big Twin and Sportster engines. Needle bearings are sized by inside diameter, outside diameter and width in millimeters, so read all three off the old part and match them. Oversize roller sets, such as +.0002 or +.0008 inch, are chosen to suit the crank pin fit, so follow your engine builder's measurements. Sealed bearings such as a 6203-2RS carry rubber seals on both sides. Some listings are single bearings and others are kits with seals, so check the quantity.
Brands here include Hot Rods, Emerson, Jims, Parts Unlimited, S&S Cycle and Prox. Pick your machine in the Ride Finder at the top of the page to see bearings made for it. A bottom-end job usually involves Crankshafts, Connecting Rods & Parts and Gaskets, Seals & Kits as well.
FAQs on engine bearings
How is a bearing size written?
Three numbers give the inside diameter, outside diameter and width, usually in millimeters. A needle bearing marked 15 mm x 20 mm x 18 mm has a 15 mm bore, a 20 mm outer diameter and is 18 mm wide. Measure the old bearing or read its markings before ordering.
Should I replace the crankshaft bearings during a rebuild?
Usually yes. Bearings cost little compared with the labor of opening the engine a second time, and reusing worn ones risks an early failure. Inspect the crank journals, and measure the clearances as the service manual describes before the cases are closed.
What does 2RS mean on a sealed bearing?
2RS means the bearing has a rubber seal on each side. The seals keep grease in and dirt out, so the bearing needs no added lubricant but cannot be cleaned and repacked. Match size and seal type to the original.
What is the right way to press a bearing into a housing?
Push on the ring that is being pressed, the outer ring when it goes into a housing and the inner ring when it goes onto a shaft, and keep it square. Pushing through the rolling parts can damage the bearing before it runs.
Are engine bearings sold as single pieces or sets?
Both. The listings show single bearings, matched pairs, crank bearing and seal kits, and roller sets for Harley-Davidson crank pins. Read the title and description for the quantity and the model each one fits, so you do not end up with half of what the job needs.
