to find true suckage, you have to go to the motorcycle world. My gs750,for example . Valve clearance is adjusted with shims, that go in a bucket, over the valvestems. 4 cyl dohc, that turns 12k rpms. If you get a magnet near the valvetrain,it will spit the shims out. Luckily, I have a tv tube demagnitizer.,lol.Last thing after working on it is the ritual degaussing.