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help i dont know whats wrong
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Posted by: charlie21

alright my 400 is making this knocking sound i have been riding it and about 2 weeks ago it started to get really loud and i have not rode it since somebody told me that i installed my cam wrong and i need to adjust my valves but im not sure i just need to know what to do

Posted by: Bill Fuller

If you installed a new cam and didn't adjust the valves it COULD be you problem.What is the compression of the piston?You could be pre detonating which means you need higher octane fuel.My guess is the valves are out of adjustment.Did you check to see if your timing chain needed replacing?If it still ran when you shut it off then you should be alright.Most aftermarket cams require a different valve lash than stock.

Posted by: charlie21

i didnt install the cam but the guy who did adjusted the valves do you know any place where i can get it checked out for free or cheap

Posted by: armysig

Here is an article on how to adjust the 400ex valves. If you have a new cam you will need to find out what the intake and the exhuast valves should be set at when you use the feeler gauge.

If you don't know, do a google search on that cam and see if you can find the instructions or the specs.

http://www.atvriders.com/articles/v...tment400ex.html

Posted by: Lowcountrydave

Hey Armysig,

Does this cover all 400EX's? I have an 06 400EX and its time to adjust the valves for the first time.

Dave

Posted by: Bill Fuller

It is the same for any 400ex.

Posted by: Lowcountrydave

Thanks Big!

Dave