400ex maintenance and restoration help!!!

[qlloyd]

I have a 2007 400ex and i know i need to replace some things in the top end of the engines. What do yall recoment i replace while im in there other than spark plug, should i replace gaskets? Check valves? what else? timing chain ?? I dont know much somebody please help thanks

[blacknblue#2]

Gaskets are a must once its apart. piston and rings are pretty much common wear parts. Check valves and maybe replace valve stem seals while your in there. If you do a timing chain i would go with an older CRF450 timing chain. its cheaper and heavier than the 400EX timing chain

[qlloyd]

Gaskets are a must once its apart. piston and rings are pretty much common wear parts. Check valves and maybe replace valve stem seals while your in there. If you do a timing chain i would go with an older CRF450 timing chain. its cheaper and heavier than the 400EX timing chain

What are the main gaskets I should replace and what are valve stem seals. And also what does a cam timing chain do and where is it located? Thanks for your help