The valve clearance of motorcycle has been adjusted to almost no clearance. How can it be started at low speed or high speed, and there is valve noise? Which parts are worn out?

Motorcycles must have enough valve clearance. If the clearance is too small, it will cause the wear of the valve rocker arm and camshaft. If the gap is adjusted to be small or even no gap, it will still ring. It may be that the valve rocker arm and camshaft are worn. In addition, if it is an ejector pin engine, no matter how to adjust the clearance, the valve sound can not be completely eliminated, and sometimes it will be obvious. In other cases, if it is a small chain car, the timing chain is too long or the tensioner is damaged, and sometimes the sound is similar to the valve sound.