Gray, this is an excellent write up. I know I'm a little late to this topic but I'm presently in the process of replacing the timing chain/valve adjustment on my 08 yz450 I've read
that some are having an issue with correct alignment of the timing marks. I found that by marking the chain and sprockets in three spots with a paint pen (one at the bottom of the
crank 6:00 and one just above the timing marks on each cam 9:00 and 3:00. After removing the chain I transferred these marks to the new chain. I found it easier to get all the
gears properly timed. I'm astounded at all the great information on thumpertalk. Thanks for the help.