Frame stress fracture, with pictures.........

Hello all,
I have a question. Has anyone seen a frame crack in this area?
I have the restoration down to the frame. There is a questionable weld repair done on the left side of the frame. It was obviously done without removing any parts off the bike. There are no other bends or damage visible to the frame that would help me find the cause of the fracture. The PO did a kegler bodge on the swingarm, so this might have been a contributing factor. The welds seem to be done at the same time and by same skilled (or lack of) welder. The frame measures correctly according to the frame dimension chart in the Workshop Manual.
Is this a common problem? I am a qualified welder, so going forward I can remove and reweld the sin, but I wonder about the cause and if there is anything else I should be looking at?

That welding is disgusting,cracks in that area can be caused by setting the isolastics to zero although the crack would usually be further down

I've never seen a Commando frame crack there. Looks like some crash damage repair.

I'ts a stress crack, there is no other damage or indication of a crash.

I have a frame with the same breaks. It was a Commando road racer with a lot of hard service and isolastics set too tight.
I brazed the cracks as well as brazed on a long plate spine or stiffener on the back of each tube. Looked horrible but did not break again

You being a qualified welder will have no troubles grinding that pile of crap off and fix it up properly, better than new and stronger with more penatration than whats been done, nothing worst than fixing someone else's bodgee job.

Ashley