Because motorcycle bearings are smaller than automobile bearings, the oil gap is also smaller. In order to achieve the best conditions for hydrodynamic lubrication, the absolute tolerance of the oil gap should be stricter than that of larger automotive bearings.
You may or may not want to know the difference between automotive engine bearings and those used in motorcycle applications. For the curious, the most obvious difference is the size-the motorcycle bearing is smaller. However, there are a few key differences, so we spoke with King Engine Bearings to get information and updates on its new racing bearing series for power sports applications.
Because motorcycle bearings are smaller than automobile bearings, the oil gap is also smaller. In order to achieve the best conditions for hydrodynamic lubrication, the absolute tolerance of the oil gap should be stricter than that of larger automotive bearings. The bearing size that affects the oil clearance value is the wall thickness. The wall thickness of motorcycle bearings should have stricter tolerances.
These differences still exist when comparing bearings used in conventional street applications with those used in racing applications. King Engine Bearings recently launched a series of bearings dedicated to power sports racing applications, such as Suzuki's Falcon and GSX-R100, Kawasaki's ZX14/R and Polaris, so we asked them about the bearing characteristics.
King has always focused on automobiles, but stated that due to the needs of end users and engine manufacturers, they decided to develop bearings for motorcycle applications, and they are looking for better solutions than stock bearings for racing applications. After extensive market research and investigation of common faults in stock bearings, King decided to respond to the call of the market and created a new powersports designated category in racing bearings. The manufacturer also took this opportunity to further expand its engine bearing product range.
King's motorcycle racing bearings are designed with three-metal XP pMaxBlack. Due to higher speeds and higher loads, motorcycle bearings should have more precise dimensions (stricter wall thickness tolerances) and greater bearing material carrying capacity. Although stock motorcycle bearings can reach 6,500 psi, King's motorcycle bearings can reach 11,000 psi, almost twice the load capacity.
When comparing the bearing characteristics of the drag racing car with the bearing characteristics of the drag racing car, King said that due to the combustion load of the power stroke, the wear of the upper bearing shell is slightly larger than that of the lower bearing on the cover side. The bearing operating conditions in drag racing are different from ordinary races. Due to the extreme loads acting on the bearings, hydrodynamic lubrication is impossible. The bearing material continuously contacts the shaft surface. This situation is normal for motorcycles and car rally races. When it comes to bearing life, King said that the service life of its motorcycle bearings is twice or even three times the service life of bearings in automotive applications. This is partly due to the middle layer of pMaxBlack, which is stronger than the middle layer of traditional high-performance bearings due to the combination of cold working and increased tin content from 2% or 3% to 4.5%. The hardness of the middle layer increased from 94 HV to 112 HV.
The pMaxBlack coating has higher fatigue strength due to its thinner thickness and higher copper content (increased from 2% or 3% to 5%). Its hardness is 18.3 HV. This is a significant increase compared to traditional high-performance overlays with a hardness of 10.3-14.2 HV. The proprietary surface hardening technology developed by King Engine Bearings further improves the fatigue resistance of the pMaxBlack overlay. This treatment produces a hardened cover surface with a thickness of nanometers. The hardened surface suppresses the formation of fatigue cracks. Experiments using King's test bench show that the fatigue resistance of the pMaxBlack overlay is 10,200 psi. This is 17% higher than the traditional three-metal bearing (8,700 psi).
If you are looking for performance-oriented motorcycle or power sports bearings in the market, King has a valuable solution.
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