on the ninja 2008 aa, the same quarter of a century proven engine, the inline-2 248cc, but it has a shim instead of a tappet rocker. Improvement, the valve clatter is quieter A BIT ONLY. Its really menggangu perasaan, haha! te..te..te..te..te..te..te..te..te..te..te..te..te..te..te..te..however the er6n has no issue with the valve clatter, only on the 250s. My 250 rocker arm is a PIA, needs adjustment every 3000++km, otherwise it would sound horrid.