I’m getting pretty deep into the top end tear down with my class on the 450. Other than being Honda’s first DOHC engine, there is another peculiarity about this powerplant. Instead of using valve springs, it uses torsion bars. They’re essentially steel rods that hold the valve in place, which are twisted in order to open the valve. They pretty much eliminated the risk of valve lift. Why did Honda put them on a UJM that only spun to 10k? I have no idea, but they’re pretty cool.
Pretty sure we found the source of my valvetrain noise in a flattened cam follower. I plan on regrinding the cams along with some other mods in order to take advantage of those torsion bars. Gonna teach the kids to wheelie once we’re done. Picture of the bike in healthier times: