There was a 4” Karata open on my K9 when I bought it from Train Man. I had problems with it bcs the steel clutch plates chopped little grooves in the inner basket so the clutch would stick and drag my ass out into intersections.—I bought and installed a new drive belt because one time I hit some gravel and some of it poked a few small holes in the original belt. It was fine and totally operational but I didn’t like the way it looked. Bought a new clutch pack and replaced (again) the inner basket and put the ‘turnkey‘ 4” Karata for sale on the Forum. No interest or offers for a month or two and then a guy called from Tulsa who was building a show bike. So sorry to say I never got his name or anything else about him as we dealt with cash. I told him about the troubles I had with the inner basket and he said he didnt care as he wasn’t planning to ride it—just show it. That was at least two maybe 3 years ago. If you can find someone showing a BD K9 with that Karata open primary around Tulsa, I bet he has the backup belt on a shelf somewhere. A bike like that would be known. Again, not a perfect, but very serviceable 4” belt for years to come……. He was building a serious show bike so I think if you know where to look you might be able to find him. Good luck Amigo…..