Flared MK 111 Feked fracture .

Thin walled flared British aftermarket metal fractured on me . Replaced with 750 aftermarket pipe on R.H. side . I only bought these pipes to change the Primary side from touching the primary , specifically the primary drain plug . I was only interested in the primary side . So now I have the thin walled flared MK 111 pipe on the left , and the new 750 aftermarket style on the right . To replace the thin walled R.H. fracture . In the bin . Started up perfect and ran great for a run . Lots of Hi- temp copper silicone with new crush gasket to the right side . Tightened up again with special Exh . tool . . J.S . Exhaust port D insert had not moved . , all good , blasted to store again and back . Do not buy thin walled MK 111 aftermarket flared steel ? Too thin . ?

Mine broke and that was a Toga system from Mick Hemmings, I welded it up.

One of the flared pipes I had on the bike before that also broke (the reason I purchased the Hemmings Toga pipes).

I bought new header pipes from AN the summer before this last summer and the flange broke off after a month of riding around. I brought it to my welder and he had to braze it back together with some sort of bronze alloy (not sure exactly what because I'm not a welder dude) It lasted about a week and broke on the vashon island TT run. Thankfully, a norton guy who lives on the island rescued me with an extra pipe he had in the rafters of his shop. When I got home I put my original ugly, but sturdy pipes back on the bike....

The new pipes from andover norton are very thin and the flange is brazed, not welded. After my experience with them, I'd rather have heavy old ugly pipes...

Not Mk3 specifically, but my experience of Mk2A balanced pipes hasn't been great - to get them to fit required a LOT of levering and forcing, and I was never satisfied with the final fit, such as it was.
Unbalanced EMGO pipes fit well enough and don't put strain on the flanges.
I've wondered if there's any association with stripped threads on 850 exhaust ports, with the shorter roses having less thread engagement.