chassis break ktm sxf 450 2019.

Perhaps internal rust was a factor.   Do you live near the coast?

There is a lot of rust inside that frame. 

Rusty Crack Bro...

A good friend of mine had a similar failure in the same spot on his 2019 250sx and the bike wasn’t even that old. Let me try to dig up a photo and date of it. 

2019 KTM250SX, 50+ Vet Rider who gets around pretty decent. Photo taken in February of 2020.

This was a known issue on the 16.5-17 frames, thought they had beefed up that area by 18 on up? I had a 16.5 FE 450 that developed a bunch of small cracks in this area, I caught it in time and KTM warrantied the frame no questions asked…..

Sick chopper mod!

In all seriousness though, I'm sorry that happened.  I'm going to check mine tonight!

Yup. His 2017 FC450 developed a crack in the same spot where all the other 16-18 frames were cracking too. Luckily he caught it early and didn’t split through like it did on his ‘19 250SX. 

My last few UAMs, I always sealed any holes anywhere in that vicinity...whether it did much, I don't know, but it definitely kept water out.

Another rusty crack. They all seem to start with the bottom weld. Clearly an issue before the actual day of failure.

2017 sx250, photo taken in July 2022

This was my riding buddies bike, a 2017 KTM 450SXF. Yes, it usually doesn't break all at once. 

I’ve always wondered if the way KTM routes the vent tube from the tank into the plastic fitting on the frame aids to the this. Surely getting soaked in fuel occasionally can’t be good for it. 

Rust or not, that should not have happened. Freakin A

I see quite a few Pierer Bike riders attaching their Radiator overflow hose to that prong.........

Yes, steel rusts, it's why after painting my Steel Bicycle / Motorcycle frames, where water can get in, I Oil Mist them, and, tell customers to keep on top of that.

But, these Pierer bike breakages, are much more than any internal rust causing failures. burn1986 is spot on with his comment.

And now we know why the 2023 frame is so stiff in the front. 

“Ready To Rust”?

Sorry, couldn’t resist.

Condensation is also a problem when sealed up.

I'd spray diesel with a touch of engine oil into the frame starting at the top and let it drain out down the bottom. Keeping the inside of the frame lubed will eliminate / prevent (internal rusting)

I don’t see a way to defend a frame breaking like that. There are 80’s steel frames out there sending  it since then. 

I think its just too thin material in a critical area…they we’re touting how light their bikes were…. 

This, can someone get calipers on that gusset and see what gauge steel it is, looks like about 18 from the picture.

Bingo , I thought the same thing 

Air fork? I have ran too low of air pressure and it will feel okay until hitting a jump and the forks will clank hard. That energy has to go somewhere. The hydraulic bottoming system on the earlier ktm forks were not the greatest and mostly relied on the air spring progression.

Light, strong, cheap. Pick 2. Well, maybe just one for that era of KTM frames. There were some long threads on this problem a few years ago. 

I had a 17.5 FE SXF 450 a few years ago and noticed it cracking from the bottom, I ended up replacing the frame and it definitely wasn't cheap but I'm glad I caught it before things got ugly. Bike had 150+ hours, but both I and the original owner were +40 local guys, nobody was doing SX on the thing. Meanwhile my '86 Honda and '89 Yamaha frames are still going strong...

There is a reason why Ktm is filing for bankruptcy !

And this ain't it!