Steve McDowall explains the Suzuki VVT System.
Ever since Suzuki announced it was using variable valve timing in its new GSX-R1000 sports bike that’s being released late this year, and that it was based on technology from its MotoGP bikes, there has been both confusion and question about how it could work and be legal in MotoGP.
MotoGP rules explicitly prohibit any form of variable valve timing and lift systems “driven by hydraulic and/or electric/electronic systems”.
But the mystery has been solved with the help of some patent drawings and a little bit of engineering knowledge.
Most VVT systems use a hydraulic system to shift the camshaft forward or backwards in relation to its drive sprocket, which then either advances or retards the valve timing.
Most commonly, that is also controlled by electronics.
But Suzuki’s ingenious solution splits the camshaft sprocket into two halves and uses steel balls in radial grooves between the two halves to shift the valve timing.
As engine revs increase the balls move outwards under centrifugal force and retard the valve timing. As revs are decreased, springs force the two halves together, squeeze the steel balls back in towards the centre and advance the timing again.
Simply brilliant engineering from Suzuki, totally mechanical in its nature and therefore perfectly legal in MotoGP!
It appears that Suzuki also has plans to use an electronic VVT system at some time in the future as well, and while this would be a far more controllable and accurate solution it would be restricted to road applications only.