My BRP triple clamps are from a YZ 250. They fit very tight on the steering stem. If I had it to do over again, I would have kept the stock clamps on and figured out a way to do an under bar mount on my own. Perhaps even the BRP under bar mount would work with the stock triple clamps.
I'm not sure, but I'm finding that stock is usually better than anything you can buy unless you are doing something very specific. For instance: Pivot pegs, ODI clamp on grips, etc.. Bling is a waste of time and money. One time I purchased a super trick set of triple clamps for my Husqvarna WR 125. They changed the way the bike felt, and not in a good way.