Yamaha Hatsudoki Kabushiki Kaisha

Hiroyuki Sakai

Shuhei Adachi

Junkichi Amano

A method of forming cylinder heads having bonded valve seat inserts. The method reduces the machining operations necessary to place the insert in place by forming the cylinder head casting with reference surfaces that are employed for determining the pressing axis and location for the valve seat insert.

Method for forming valve seats

Valve seat-bonding area structures of a cylinder head unit, wherein a valve seat made of a metal different from and harder than that of the cylinder head unit is bonded to a circumference of a valve opening of the cylinder head unit, which structures are characterized in that a second tapered guide surface, which has an open angle larger than that of a first tapered guide surface with respect to an axis of a valve shaft, is formed outward of the first tapered guide surface in order to prevent pitting and cracking of the surfaces during grinding and improve the gas-interchanging efficiency.

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Iwata, Japan

Hiroyuki Sakai