Having suspended the public launch of the 2011 Ninja ZX-10R to investigate a technical issue, Kawasaki have now revealed the cause of concern - the valve springs.
According to an official Kawasaki press release: "It had been discovered that when some examples of the new 2011 Ninja ZX-10R were operated at high rpm under unique riding conditions - such as operating on a racetrack - the intake valve springs could surge. Should this rare incidence occur it could cause one or more intake valves to seat improperly, resulting in poor engine performance.
"Having examined the very small number of machines which exhibited this surge phenomenon, the Kawasaki factory engineers have designed and fully tested a countermeasure which solves the problem without affecting any facet of the new engine’s outstanding performance.
"On the limited number of machines produced so far, the camshaft, valve springs and spring retainers for intake valves are being replaced to prevent the valve spring from surging. The same design update is automatically being incorporated into the ongoing production run."