what's this vibration/rattling noise?

i just bought a 98 yz400 i love it except the head it pretty noisy its a rattling/vibration noise is this normal? this is my first 4 stroke could it be the valves too loose if so how do i check

much thanks,


i have a 98 and it makes the same noise.i wouldnt worry about it to much.i took my motor apart 50 times to try and fix whatever was causing noise nothing worked.the good news is i rode bike for almost 2 years with noise and never had any problems.i just recently installed 420 bigbore kit and had some port work done.its still makes the noise but not as bad.

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