I have a rattling/buzzing noise coming from under the gas tank when I get on it. Any ideas what this could be?

 

Could be a rattlesnake. I'd be careful until you're sure it's not.

 

<div class="FTQUOTE"><begin quote>Originally posted by: budedm

Could be a rattlesnake. I'd be careful until you're sure it's not.</end quote></div>

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what year is your 400ex

 

air intake tube??? metal sound plastic???

 

my buddie has a 400ex and so do i he had the same problem, and after some research we found out that it was most likley a blown bearing holding the cam down at the top of the head. is it a clicky rattle or more like just from vibration?

 

sounds like more of a vibration like the heat shield. checked that and it was tight. I was thinking it could be the valvetrain

 

possibly you should get a haynes book for it very helpful

 

i have the same problem. i just got a brand new 2008 400ex and the first time i rode it there was a buzzing noise, still cant figure out what it is but sounds like its coming from somewhere upfront

 

i am in the same boat as you.