Potential front brake upgrade

[Chopperpilot]

I'm about to go get a 2009 KLX250SF and start turning it back into a dirtbike from a factory super moto. I realize that may sound stupid, but it's a better deal than on any KLX230 or TTR230 that I was looking at for my daughter or my GF to ride along with me. Key points being lower seat, and not much happening if you twist the throttle all the way.
Well the 250SF comes with 43mm USD forks on it and a 300mm brake rotor, 17" wheels all around. The fork lugs are definitely different than the regular KLX lugs, but I'm pretty sure I saw that familiar old 15mm KDX/KLX axle sticking through them. I figure I have all the parts to turn this back into a dirtbike mostly because I have the KDX 21" front wheel. But that got me to thinking, what about the brake rotor? Well it looks like both the 250SF and KDX/KLX650R all use a 4 bolt rotor mount. So I'm betting that the 250SF 300mm rotor would bolt onto a KDX hub. Then you'd just need to machine out a spacer for the caliper. The guy who SM'd my KLX650R had one done up and I'm hoping it's for a 300mm rotor (stands to reason that's a common size). When I get the bike, I'll see if the rotor mounts onto the KDX rim and see if my brake spacer is made the right way to space it out, and then post pics!
It's been so long since I had the SM wheels on the KLX that I forget some things exactly, and the wheels were mag wheels from a Suzuki SV650 (IIRC), so the caliper spacer might have an offset to it that wouldn't work anyway, but we'll see.

[Chopperpilot]

Ok, bought the bike, and it's a go! The KLX250SF (Super Moto) does use the KDX/KLX front axle and a KDX front wheel fits right in there. The giant 300mm rotor has the same 4 bolt pattern as a KDX. I'm wondering if the KLX250SF front brake could just be swapped over to the KDX (and most other) forks with it's larger spacer. I think this bike will be great for my daughter to poke around on....... when you twist the throttle, not much happens!

[assquatch20]

Could be promising news. I've thought about getting sumo wheels for the KDX down the line and wondered about brake upgrades.

I'm curious about something else, though. Is the KLX rear axle the same as the KDX you think? Or maybe the KX250F? That would be ideal for something I'm considering to try.

[KDXGarage]

KX250F rear axle is 25 mm diameter. Check out bearing inner diameters when comparing axle diameters.

[assquatch20]

KX250F rear axle is 25 mm diameter. Check out bearing inner diameters when comparing axle diameters.

I'm not trying to derail the thread but where did you find the ID for the bearings? I don't even know the diameter on the KDX. What I'm wondering is if I can hook up my single wheel trailer with the KDX. The maker uses a skewer on hollow axles and makes the hardware to mount to the KX250F so I thought it might be an easy adaptation.

[KDXGarage]

You can just look up the bearing info. 2003 and newer KX went up to 25 mm inner diameter.

KDX and older KX's for many years were 20 mm inner diameter.

The axle inner diameter would go up as well.