Well last week I bought an 06 crf450x. I had to fix a couple minor things ( I thought) and as usual I changed the fluids in it. ( I always do that when I buy a used bike) after the oil change I started it up and the engine kocked until the oil pressure built up. it has not done it on any restarts since, but that bothers me now I am thinking I got screwed and this thing needs rebuilt. does anyone elses knock after oil change until oil pressure builds up?