When adjusting you chain tension on a Honda, (like the 400EX, 300EX, 250R) don't even try to use the procedure they outline in the owners manual. They have you placing the hex wrench (that they supply for loosening the nuts) in the slots on the adjuster ring and prying on that to turn the adjuster. It works poorly, and will eventually hack up the slots on the adjuster.

I just use a large MotionPro shock preload adjustment spanner. The wrench is huge, and provides lots of leverage for large or fine adjustments. Works great!

 

How about another one.....if you overtighten your chain your suspension will stretch the chain as it works through it's cycle and lead too a shorter chain life. Always run a good chain lube.