The force produced from a rotary engine would result in a smoother ride... When an ordinary egine runs the pistons go up and down, this shakes the engine in the same direction - it's the reason 4-cyliners fire in 1-3-2-4 order, or similar - if they fired in 1-2-3-4 order the engine would shake it and the vehicle apart. A rotary engine will produce centrifugal force. As for gyroscopic effect, I shouldn't think it would be significant enough to make the bike unable to corner. Rotary engines are tiny, because they're so powerful. It would be interesting to see if you could take the engine from a mazda (I'm told they have two rotary engines that work together, around 700cc) and put it in a motorbike. Seeing as motoGP is restricted on engine displacement, a 700cc would be massively more powerful than a 2 or 4 cylinder engine They'd probably make it so you'd have to run maybe a 300cc engine for a rotary - think of the weight saved!