Ask MO Anything: Why didn’t the Ducati Supermono just use Normal Counterbalancers?

Instead of a dummy connecting rod, the LC4’s main counterbalancer spins opposite of the crank, at the same speed, to cancel out primary imbalance. Note how the counterbalancer will occupy the connecting rod’s space 180 degrees from now for compactness. A bigger bore and shorter stroke that year meant less reciprocating mass to balance. The KTM engine definitely has more spinning mass than the Supermono’s single con-rod, but its near-total vibration cancellation of a much bigger piston is worth it.