Seeing as we've been discussing supermoto setups, and this forum has a weird way of turning up even the rarest unobtainium, figured I'd post up my current project and see what shakes out. I currently sumo a ye olde 1992 Yamaha WR250ZD smoker. It's rocking a Behringer 6pot setup up front and is a dream on the brakes. Something about the bike though apparently intimidates me when it comes to dirt so I am not jumping it which is kinda killing my performance on the bike. I say this as I picked up a 2019 KTM 150 SX to go out and actually learn how to ride dirt on and I'm having a ball just throwing that thing off jumps. Haven't quite cleared a double properly yet as I've no reference for judging gaps and the needed speed to do them, but I've cased lots and the bike just shrugs it off while the evil little motor constantly eggs me on... It's been strongly suggested that I try sumoing the 150, so that's what I'm working on doing. Wheels are on order, next item to address is brakes but I want to go a different path than the Yamaha. I need this bike to be easy to swap back to dirt duty, so I'm not going to toss a 320mm rotor on it. For short track I'm confident a floating 260mm (stock) or 270mm (oversized) rotor will be sufficient. Goldfren happens to make both for reasonable prices so I'm good there. What I'm looking to track down now are upgraded calipers. KTM uses a Brembo two piston floating caliper. They offer a 'hardparts' billet unit, the 'SXS' version as an upgrade, new cost is enough that I'd just go full 6 pot Behringer again instead. Going back in time, circa 2004ish I think KTM used a similar cast Brembo to current, but with 28mm pistons instead of 26, some dirt riders have tracked those down as upgrades. Last item I'm aware of is a Brembo, four piston billet floating caliper, again with the SXS label but apparently only available to factory KTM MX racers? Anyone (Robby?) got experience in this arena that can either tell me there's no gain from all of this, or chase down PN XXX, or 'yeah, I gots one of dem collecting dust...'?
What about a radial caliper adapter? You could likely shorten it to allow for a 260 or 270 rotor, and it would be dead simple to swap around if you wanted to go back to the little rotor for dirt. Or just leave it on for dirt and deal with awesome brakes... Can you link to a picture of the caliper that you seek?
The problem with radial adapters is finding a caliper that will fit, sumo wheels being much smaller diameter mean there isn't much space by the spokes where the caliper needs to go. Shortening the adapter for a smaller OD rotor makes the problem even worse. I went through this with my WR when I was first setting it up. Got an adapter, a matching Brembo off an SMR IIRC, and no good, the back fouled the spokes. No problem I thought, it's not much, I'll just touch up the back of the caliper on my belt sander... About two seconds later, literally, I blew through the back of the already milled to the limit by the factory caliper and exposed a piston. What no one mentions is the bikes running those setups have the rotor spaced further out from center, and run wider clamps. This is the older gen 'SXS' caliper upgrade: Current generation is curvier: The only reference I've found to the four pot is: https://www.tawperformance.com/brembo-ktm-cnc-2-floating-piston-caliper-xq21361 but that looks strikingly similar to the old two pot, and I dunno how you'd get a four pot to fit with the extra width required, with again offsetting the rotor and all that fun which I'm not interested in. And just to complete the pictorial, Gold Fren makes upgrade calipers as well:
