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General => General Discussion => Topic started by: kymco God on March 20, 2011, 02:10:26 PM

Title: valve bouncing
Post by: kymco God on March 20, 2011, 02:10:26 PM

hello everyone :D, can some one tell me what valve bouncing is and can it couse you bike/scooter any harm?
and is there andway you can stop the valves bouncing?
cheeeeeers :)

Title: Re: valve bouncing
Post by: CROSSBOLT on March 20, 2011, 04:03:21 PM

Valve bounce happens usually at high engine rpm and involves the combination of valve mass and valve spring constant. The valve literally hits the seat upon closing and lifts off the seat to then close under spring force. Ducati has a "desmodromic" system where the cam opens AND closes the valves to eliminate the possibility of bounce. Springs are cheaper and lighter and can be made with different rates to eliminate bounce at high rpms. Honda and Kymco have figured all this out years ago through racing and testing so I don't think we have to worry about valve bounce. Plus our machines have rev limiters to keep the revs below 9-10000 rpms.

Karl