I was surprised how easy it was on this little 4 stroke. All I hear is people whine and complain about it. They just don't want to work on anything or they hate paying attention to detail. And I'm not going to wait for a couple days for a dumb shim to come in the mail - or spend a day and $20 in fuel looking for one! If I order anything it's going to be a new set of valves and a shim kit that will last me my whole life.
I was about to break down a how-to on how I sanded it down but it's too simple and the pictures would only work to convince the nay-sayers. Belt sander had a worn out 180 belt on it so it wasn't too aggressive. At first I was wondering how the heck I was going to remove material from such a strong little piece. A file was a joke against it. The sander really wooped up on the shim but I had to use a small socket to hold the shim in the end of it. They heat up instantly when that much friction is applied. Cleaning up the rough side is more of a chore for sure. It has to be polished smooth to keep it from cutting down the surfaces when in operation (I imagine) . So my brand new knife sharpening block and a few drops of oil cleaned it up in about 10 minutes of work. A machinist friend of mine said that's how a couple professional motorcycle mechanic friends do it. You just have to have the tools handy or else you might as well start driving or order some up on the net.
And after doing the valves on a couple shim and bucket Lexus V8 DOHC engines this single cylinder is as easy as taking out the trash.
That Triumph will be a fun exercise for you. It won't take long. I'm sure there are all sorts of how-to pictures online. It's really almost odd to have to adjust the valves on modern streetbike engines. They don't take nearly the beating that off road equipment does.