I still have the 09' KX450 Christini. Since installing the Rekluse clutch I've thought a lot about a left hand brake. So I got a a hand brake for a SkiDoo Rev with a brake lock. I don't know if I'll ever need it in the future but I sure could have used on in the past. The KX rear brake cylinders do not work with the kits that are sold to make a left hand brake. I went to my bone pile and found a CRF450R rear brake cylinder.
Phil at Moto-Heaven lined me up with the right brake lines and cylinder block off unit,,, they arrived so fast it made my head spin,,, called him on a saturday and they arrived monday.
It didn't bolt right on so I ordered a WorksConnection brake guard. Drilled a hole and game on.
Made a home made mount to have the hand clutch just above the left brake.
Also I had a small problem with the part that slides inside of the brake cylinder to convert it so that it has no reservoir,,,the O-ring kept hanging up where the level glass is located and cutting the O-ring up,,,I finally tried putting the o-ring in alone then followed with the plastic insert to block off reservoir.
Hope it was worth the trouble.