In order to enhance engine performance of racing motorcycles, aiming increase of critical engine speed, a valve spring retainer made of lightweight powder aluminum alloy has been developed. The high strength abrasion resistance aluminum, “NCP 400” (Nano Crystal Powder metal with crystal grain size of 400nm), hard grains are blended with optimum amount to get abrasion resistance to Nano Crystal Powder aluminum alloy consisted of Nano-sized crystal grains, was created. Optimum temperature control and forging method for the material property established the warm-precision-closed-forging technology that post-machining is unnecessary in parts manufacturing. Verification method of safety factor was set up, by which the load of retainer could be evaluated quantitatively based on the movement of valve train during operation.
Article of Honda R&D Technical Review Vol.15 No.2 (159 - 166)