400ex rattling noise - ATVConnection.com ATV Enthusiast Community

ssprofession · #1 (**permalink**) 03-03-2009, 05:21 PM

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

budedm · #2 (**permalink**) 03-04-2009, 12:28 PM

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

ssprofession · #3 (**permalink**) 03-04-2009, 12:52 PM

<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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Miami_Vice454 · #4 (**permalink**) 03-04-2009, 04:27 PM

what year is your 400ex

moto134 · #5 (**permalink**) 03-04-2009, 06:14 PM

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

quadxaddict · #6 (**permalink**) 03-04-2009, 07:11 PM

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?

ssprofession · #7 (**permalink**) 03-04-2009, 10:07 PM

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

quadxaddict · #8 (**permalink**) 03-05-2009, 02:57 PM

possibly you should get a haynes book for it very helpful

Miami_Vice454 · #9 (**permalink**) 03-08-2009, 10:24 AM

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

Miami_Vice454 · #10 (**permalink**) 03-08-2009, 10:37 AM

i am in the same boat as you.