The valves are set apart at a 21.5 degree angle that allows for a flat combustion chamber ceiling. Steel exhaust valves were used, we assume, due to their durability. After all, exhaust valves are exposed to more wear and tear than their prissier next door neighbors. Also, intake valves are larger. Therefore, utilizing titanium for their construction results in the greatest weight savings.
Lighter valves mean smaller springs.
Smaller springs equal, well, you get the idea. Engine speed is controlled by a 40mm flat-slide carburetor. The exhaust system features a titanium header, stainless steel pipe and an aluminum muffler. Vibrations are controlled via a gear-driven balancer that also happens to push water through dual radiators. Dual lubrication systems keep parts slick and smooth with the engine and tranny having separate sumps.