Just some more ideas and thoughts, some maybe from before, some maybe not. 1)Get a magnetic drain plug, you might not believe the fine ferrous particles and also larger bits if they come loose. The magnetic plug is a good idea right from the dealers floor. Don't drain the oil just lay the bike on its side and swap the drain plug. 2)Drill the lower shock mount bolt and link for safety wiring the lower damper
bolt. Cheap insurance and you might not overtighten the bolt and strip the link if you know the bolt is tight and can't fall out because of the lock wire. 3)As a cheap way to move your bars forward on 01's and older 400's and 426's see if you can buy a used or take-off YZ250F upper triple clamp (Thanks Steve). 4)For the chain slide wearing into the swingarm, before the recent post I removed the chain, removed the upper bolts securing the slide, cleaned the slide and swingarm with lacquer thinner then glued the slide with RTV silicone, the black stuff used for car valve covers,then reinstalled the bolts while the RTV before the RTV cured. 5)Make a block two inches high to place on the chain slide and set the chain slack consistantly and not too tight. 6)Buy the aftermarket sproket bolts, (I got the Talons) $12 of cheap insurance. 7)Reroute the breather hose from behind the radiator. Route down the side of the cylinder between the clutch cable, then in front of the C/S sprocket to "v" area between the frame tubes just inboard of the footpeg. Use the original breather hose holder and move it from the ignition cover to the area in front of the C/S sprocket. Moving the hose keeps the oil from covering the side cover and left frame tubes, now it will go out the bottom by the chain.
I've done all these non earth shaking items and seem to have had good luck with minimal effort or expense. Just some thoughts to go along with the old standard of grease all the bearings.