Faring of course, then I removed the plastic air/heat deflector that's under the fairing. I took 2 of the 3 fan bolts out (the ones on the right side)leaving the upper left one. I pivoted the fan counter clock wise as far as I could. This leaves just enough room to get your hand and wrench in there to get it out. Sprayed a little brake cleaner in there to clean it up and hit it with air compressor before removing. Once I had the sensor out the wire is long enough to pull the sensor to the side to clean it a install the new ring. Once the new oring is on the sensor I put a few drops of gear oil on it and just rocked it as I twisted back and forth and mine literally popped right in. I know some haven't had that kind of luck.
some folks have said it is too tight of an o ring, but I think its a perfect fit, you can definatly tell its tighter compared to the oem one, I simply pinched it into the groove with my finger nails as I was inserting it, and it popped right in...
when I did the first one I did remove all the mid and lower plastic, and the black front pieces, and so I could completely clean the engine I removed the top radiator mounts and rolled it forward onto a piece of cardboard covering the front fender, this allowed plenty of room to completely clean the engine front, and also allowed room to check the header mounting nuts, which were to my surprise, correctly tight already... which surprised me as soo many have reported thiers were loose... lucky I guess.