I have a query regarding my bike. I had purchased bajaj discover dts si100cc. After 4000 kms, it gives some knocking noise from drive chain like 'chuck chuck'.. I thought that the chain may crashes with chain cover. I had taken the bike to the fitter. He had said that the noise was because of oil. There is no crashing of chain. I did not understood that... Is it is possible that the noise was because of Oil???