I know the history on all 16 non have had contact and are straight and true, both bikes were stock road bikes both engines hadnt even been opened. The inlets are out of a 18000 mile write off bike I broke up. They only need a clean. The exhaust valves are the best set out of 3 I have at the moment they came out of a head on a motor I bought with 12000 on the clock. They too need a clean but are all good with clean history.