This paper describes the design and development of a direct acting valve train for high speed operation in a racing motorcycle engine. At the outset of the project the engine speed limiter was set to 14000 rpm and this was eventually raised to 16000 rpm. The paper covers the evolution of the design and includes descriptions of the components including camshaft, tappet, shim, retainer, valve and valve springs. Valve train dynamic analysis software was used for the following tasks:

• Assessment of the influence of the changed parts on valve train dynamics and durability
• Design of new cam profiles
• Setting speed limit for each build level
• Investigation of failures

These activities are covered in this paper.

SAE 2007-01-0264