: ▁Des mo ▁four - val ve , ▁liquid - co o led , ▁ 4 0 ° ▁included ▁val ve ▁angle , ▁( 8 5 1 , ▁ 8 8 8 , ▁ 9 1 6 , ▁ 9 9 6 , ▁ 7 4 8 , ▁Mon ster ▁S 4 , ▁Mon ster ▁S 4 R , ▁ST 4 , ▁ST 4 s ) ▁ ▁Test ast rett a : ▁Des mo ▁four - val ve , ▁liquid - co o led , ▁ 2 5 ° ▁included ▁val ve ▁angle , ▁( 9 9 6 R , ▁ 9 9 8 , ▁ 9 9 9 , ▁ 7 4 9 , ▁Mon ster ▁S 4 R ▁Test ast rett a ) ▁ ▁Test ast rett a ▁E vol uzione : ▁Des mo ▁four - val ve , ▁liquid - co o led , ▁ 2 4 . 3 ° ▁included ▁val ve ▁angle , ▁ 4 1 ° ▁val ve ▁overlap ▁angle ▁( 8 4 8 , ▁ 1 0 9 8 / 1 1 9 8 , ▁Street fig h ter ▁ 1 0 9 8 ) ▁ ▁Motor cycle ▁design ▁history ▁Duc ati ▁has ▁produced ▁several ▁styles ▁of ▁motor cycle ▁engines , ▁including ▁varying ▁the ▁number ▁of ▁cyl ind ers , ▁type ▁of ▁val ve ▁actu ation ▁and ▁fuel ▁delivery . ▁Duc ati ▁is ▁best ▁known ▁for ▁its ▁V - t win ▁engine , ▁called ▁an ▁L - t win ▁by ▁the ▁company , ▁which ▁is ▁the