The low foot pegs are about 30mm lower which leaves the brake lever too high. I decided to sit down next to the bike with a few glasses of wine and start thinking about how I could adjust the brake lever without making any irreversible changes to the bike. This post is my solution.
I found a way to drop the rear brake lever 20mm which feels fine with the new low pegs installed. I also managed to make use of parts already on the bike and the whole thing is totally reversible.
Click the photos for larger versions.
When the old foot pegs are removed you end up with these bits...
Note the fat washer and the spacer, I will use one spacer and two fat washers, one from each peg. Using these parts I will create this...
With the brake lever removed I just slip the spacer over the stop pin and both fat washers on top. The washers are slightly too large so I had to reduce them in size. I don't have a lathe (If I did I would just make a full size spacer and not bother using the parts from the old pegs).
This is how I reduced the fat washers down to a diameter of 18mm. I used a drill and a file and bolted the washers to a screw so they could be held in the drill chuck. It also cleans them up nicely as they are pressed so the edges are rough and not square. It took about 10 minutes to get them down from their original 20mm. I finished them off with some 200 grit wet 'n' dry to polish them up.
Next I drilled a 2.5mm hole in the stop pin tight to the washers so a split pin can keep them snug.
With a 18mm washer diameter I get about a 20mm drop at the brake pedal and can still manage a 2.5mm blow-by clearance at the brake cylinder piston with the adjuster screwed fully in like this...
Here it is all fitted back to the bike. You can't put the small black plastic cover back on top of the brake pedal but thats a small price to pay I think.
Update: I found the pedal was actually a little too low after further testing so I used a 16mm washer size so that the brake pedal only drops about 15mm.
Note on earlier bikes the fat washers were welded into the peg mount but I'm sure you could find some at a hardware store pretty easily.