I carried this procedure out on my '06' Ulysses. It will work on all the XB range of bikes, but you may or may not need to remove the brake pedal on your model.
The reason for this mod is to avoid paying for a FS belt tensioner, which is often fitted to the XB range by their owners, to reduce the tension on the belt, bearings and to allow stones to go through the belt pulleys without cutting the belt.
I reckon that reducing the tension by modding the STD tensioner should at least help the belt and bearings, so I've given it a go. This is currently still under test, but 500 miles later and everything seems fine, no belt marking nor running off the pulleys at all, and coping with flat out speeds.
So after evaluating the job and a cup of tea, I slackened off the belt, (by undoing the rear spindle), removed the front pulley cover-(to remove tensioner fixing washers), removed the rear brake pedal, then loosened the tensioner fixing nuts. Then you need to remove the pulley wheel to get the bracket off.
I measured the hole diameter first, then machined, (read filed), 1 mm out from the centre of the bottom hole, in a 10-11 o'clock direction-(bracket fitted orentation). The reason for this is, that it allows the tensioner wheel to move away from the belt, and lessen the tension on it, (without weakening the bracket).
After rechecking the hole measurement,(+1mm MAX) I refitted the bracket, and left it slack, tightened up the rear wheel, then tightened up the tensioner bracket, and hoped for the best!
I test rode the bike about 100 miles, and when it had cooled down, I checked the belt, and thought that there was too much slack, about 25mm of movement up and down, and you could easily turn the tensioner pulley by hand. But when I got home, (another 100 miles), I could just twist it 90 degrees, which is about right for a cam belt on a car which is similar in design to the drivebelt.
The bike does seem to roll easier, and there is no added 'lash' in the drive line when riding, so we just have to wait and see............
NOTE: I wouldn't take out anymore than 1mm, as just 1mm at the pivot (bolt hole) will be multiplied by the length of the tensioner.
If anyone tries this themselves, then it's up to you what you do to your bike, not me. I am just trying it as a cheap alternative to the FS tensioner.