Complex sentence: In 1995 Walter Roehrich began construction of a two stroke V twin 115 hp Roehr Rv500, using Yamaha YZ250 top ends on a prototype crankcase, and this was shown to the press in 2000.
Split into simpler sentences: In 1995 Walter Roehrich began construction of the 500cc two stroke v-twin motorcycle, using Yamaha YZ250 engine parts on a prototype crankcase. The result was the 115 hp Roehr Rv500 that was shown to the press in 2000.