I'm ready to do this mod now, most everything else on the bike is about perfect. How long would you say it takes?
Not sure who John is, but here's some input if you want it. Now that I've been into the engine, I could probably do the mod in around 30 minutes. The most time consuming part is taking your time moving the exhaust cam. You need to be very careful when doing this as to not let the cam chain slip off of the crank. It is also a pain to try and keep the engine at TDC. Some have suggested keeping the bike in 5th gear. I didn't try it, but seems like it would help. Just make sure your timing marks on the intake cam stay where they're supposed to be, then set the exhaust cam off of that.
If you've adjusted your own valves before, you could easily do this mod in a half hour. If not, maybe an hour.
My tips. Don't remove the plug on the case in order to turn the engine over with a wrench. Just have someone use the kick starter while you watch for the "I" mark in the hole. If you take the lower plug out, you will lose some oil. Not all of it, but a significant amount. Also, I don't see why you would have to remove the cam chain tensioner. Just use a small screw driver (turn clockwise) to lock it. Also, be carefull removing the valve cover. You will want to re-use this gasket. Hope this helps.