<Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2009) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2009) (Learn how and when to remove this template message) </Td> </Tr> <P> The engines in these bikes use an over-square design, which means that the diameter of the cylinder is larger than the stroke of the piston . This allows for higher engine speeds and a reduction of reciprocating mass . Another technology that is used is short piston skirts . The "skirt" area of the piston is the portion on the side of the piston which comes into contact with the cylinder wall and aids piston stability . While the introduction of the shorter skirt on the piston helps to reduce reciprocating mass, it also leads to more "rocking" of the piston, or minute unwanted rotation of the piston around the axis of its wrist pin . This leads to more frequent maintenance intervals for the pistons, piston rings, and cylinder walls . </P> <P> CRF - F </P>

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