06 YZ450 maint. questions

The bike has been perfect. Have studied the 2006 YZ450 reliability data from many experiences on this site. Has about 50 track hours by a plus 40 Int. rider. Ridden fairly hard... for me, I guess. Quality JASO oil changed regularly, clean air filter etc. I am going to replace the clutch plates, top end and timing chain, using OEM pieces. My mechanic insisted on having the head rebuilt on my 2005 using stainless springs etc. I am guessing that is overkill and am not planning head work, except for valve adjustment as needed. Does this sound about right? Thanks.

If none of the valves have closed (lost clearance) beyond the point where they are .01 - .02 below spec., then disassemble the head and replace the valve springs and guide seals using OEM parts. The whole set of springs is like $40 retail, and is just cheap insurance. When taking the head apart, be careful to keep the buckets, shims, and valves marked or stored in such a way as to insure they go back in their original locations only. Remove the carbon from the valves by dipping in carb cleaner (keep the valves marked, remember. Tie some wire to the left intake and exhaust to ID them. The center intake is shorter than the others) then wire brushing it off. DO NOT lap the valves, ever.

That should be all you need.

A valve needing adjustment beyond these limits almost certainly needs replacement.

Thanks Grayracer. Will do.

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