500cc race

Double overhead camshafts with chain drive.

Air-cooled cylinder

Spherical head

Diagonal valves

Raceted by Gunzenhauser in Austria

Made and designed by the Austrian engineer Apfelbeck. (...- 1987). He has worked for many car and motorcycle brands such as BMW, Puch, Rotax, KTM,... But you could order from him special racing blocks that never went into big production. So really unique blocks. He had also patented his special cylinder head with special placement of the valves. This was a spherical head. This is a spherical combustion chamber where the valves are angled. The valves were also placed diagonally. This means there was an exhaust and an inlet valve on one ridge. Normally there are 2 inlet valves at the back and 2 exhaust valves at the front. At racer the inlet valves were large when the exhaust gave the side of the inlet the head was weak because of the large valves. By putting a small exhaust valve next to a large inlet, this head was stronger and there was room to put even bigger valves. Because of the double carburetor and the fall-stream system the inlet gasses passed the exhaust valve and it was cooled down. The cams are conical.

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