Remedies
Stiffer valve springs can help prevent valve float and valve bounce, but only at the expense of increased friction losses and higher stresses in the valvetrain. Various techniques have been used to offset the effect of stiffer springs, such as dual-spring and progressive-sprung valves, roller-tipped tappets, and pneumatic valve springs. Pneumatic valves have been used in Formula One racing. Since the 1960s, Italian motorcycle manufacturer Ducati has used a desmodromic valvetrain to counter this problem and allow for higher engine speeds by using positive closing as well as opening of the valves, without springs. The system consists of a mechanical lifter mechanism that uses a second rocker arm to push the valve closed.
Read more about this topic: Valve Float
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