Motorcycle Engine Bearings

Engine bearings are responsible for supporting the crankshaft, camshafts, and some other rotating parts while reducing friction between them. There are three main kinds of bearings found in motorcycles these days: ball, roller, and plain bearings. Actually, the last type is most commonly used in modern motors. Plain or journal bearings work thanks to a thin oil film that is formed between a rotating shaft and bearing. The thickness of this film is measured in microns, but oil viscosity and pressure make it strong enough to avoid direct contact between metal surfaces.

As for the material used, journal bearings may feature two or even three layers of metal. The inner layer is a special soft coating that allows for avoiding scratches on a solid shaft caused by small particles of debris. In general, plain bearings can last incredibly long and withstand very high revs, given that oil quality and pressure are high enough. In the meantime, roller or ball engine bearings are still successfully used in the legendary Big Twins by Harley-Davidson and some other motors, and there are a couple of reasons for that.

First, the constructions employing such bearings are less vulnerable in case of low oil pressure or viscosity. Second, they are cheaper to produce. Less material is needed to support a bearing, and it doesn't need a special oil passage that could potentially get clogged with dirt and affect lubrication. Motorcycle engine bearings are selected taking into account numerous factors, and over time, it gets clear whether the choice was right. For instance, in the late 1990s, there was a problem in Twin Cam engines related to the failure of the rear cam ball bearing, and it was resolved by the installation of the tapered roller one that could better withstand high loads. In our online store, you will find an assortment of quality engine bearings for your bike.