Bore 68.4mm Motorcycle Piston Ring Set For Kawasaki EX400 ER-4N Z750 ZR750 Z750S Engine Parts Fit For Kawasaki EX400 Ninja 400R ER400 ER-4N 2011 to 2013 Z750 ZR750 2004 to 2012 Z750S 2005 to 2007 motorcycles standard 68.4mm bore piston ring kit sized compression oil control rings match 68.4mm cylinder bore to recover stable compression lower excessive oil consumption ring material withstands engine temperature friction during daily RPM riding accurate ring gap design prevents carbon accumulation inside cylinders to extend piston cylinder life complete matched ring combination maintains balanced lubrication reduces internal engine component wear