The pistons were simply 2000GT pistons made of Lo-Ex material. At the beginning the cylinder head had very compact cooling fins, but these grew during development.

The transmission parts layout was taken from the YR-1, like clutch, gears, etc. As for the performance, the prototype engine gave only 20 HP. By re-working the cams by hand during the following months we got 42 HP. Finally we reached 53 HP. Oil leakage was the biggest problem in the early stages of the development, but this was fortunately cured later.

P.S. I do hope it is clear now that the anchester of the XS1 is not the Horex, (even Mr. S. Honda looked more to NSU than to Horex), but a combination of James Bonds' Toyota 2000 GT and Yamaha's own YR-1! Also Hosk did not appear at all in the scenario as some people did think.