Yoshikatsu Nakano

Development of HLA for High Speed Motorcycle Engine

In order to improve maintenance free operation of the motorcycle engine with DOHC-16 valves In-Line 4 cylinders design by decreasing the labor and cost involved in valve lash adjustment, it has become necessary to develop a Hydraulic Lash Adjuster (HLA) which is compact in design and has a thoroughly high speed valve motion at more than 10,000rpm. This paper describes the process of developing a compact HLA. For instance, the lack of the rigidity of the HLA itself was solved by the extensive analysis of the engine valve motion as well as the behavior of the HLA. As a result, an HLA system with compact design and high speed capability of the engine valve motion has been developed. In addition, it operates better than a mechanical lash adjuster in idling stability, cold startability, warm-up capability and somewhat in engine power, and also it operates more quietly.