Overhauling the cylinder-head & valve train will always give more reliable results when as many items as you can afford are renewed rather than reused.
Top flight race engineers don't repair the old inlet and exhaust valves, springs, seats, collets, retainers and tappets - they replace them all with new along with cam chain, guides and tensioners.
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Add as many items as you wish to the same shopping cart, new retainers 120091091 collets 120111053 tappets 120320009 & seats 160071228 for example, and still only pay the same single fixed price shipping cost. Engine work to carry out? Try this pro-workshop gasket sealant 08CRAHLG120G; easy to apply and with excellent results! This component may have other applications within the Kawasaki model range, so please make sure you order the correct part number for your application.