04 450 exc rebuild Parts needed?

Bike has 350 hrs. Valves always adjusted regularly and well serviced. Starting to get a little noisy. What parts should I be expecting to replace soon? Should I wait till it craters or fix it sooner?

Edited by ehall

I have an '05 EXC.  I did a top end at about 350 hrs.  This was a cylinder replate, piston, rings, head work and new valves.  DJH (Dave Hopkins) was the guy I got all the engine parts from while I did all the tear down and assembly.  On the head you should consider Kibblewhite over-sized valves.  I have put another 100-150 hours on the bike since and the valves never move now.  Total cost including a couple special tools was about $800.

I was quite happy with everything DJH did and used him for my crank work also when my bottom end crapped on me.  Another RFS engine builder that is highly regarded around here is Travis from Thumper Racing.

It may be better to do it now before something grenades in there and causes more damage.

What do you mean by noisy?  These engines are noisy when they're new.  Perhaps you have an issue with your cam chain / tensioner or rocker bearings.  There's other common things that can cause noise in these engines like a clutch basket or loose crank nut.



I believe the noise is a loose cam chain. I just ordered the DJH tensioner. I will see if that quiets it down while I am ordering the rest of the parts. I was looking at the kibblewhite kit that comes with valves, springs and retainers. Any thoughts?

Are you sure your old tensioner is bad?  How many clicks did it have when you removed it?  Maybe it's time to replace your chain.

I can't comment on the Kibble white kit as I had Dave install them.  I don't have the skill nor expertise to machine the valve seats.  Engine disassembly and assembly is well within my wheelhouse but I wanted a pro to handle the valves.


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