Frame Engine Mount Weld Failure!

[robtg]

Could it be possible that an owner of this bike
neglected to maintain proper torque of the engine mount fastener
i.e. it was loose, possibly for some length of time, and the resulting vibration / stress ...
might be the source of the cracking / weld failure ?

I have witnessed similar results of continued vibration / stress.

Take a look at the first foto. The weld barely touches the edge of the piece and little penetration.
If the weld was good, the frame tube would be the first to crack---in my opinion.

[vanzen]

The weld barely touches the edge of the piece and little penetration.
If the weld was good ...

... I'll agree with that.

[ME 109]

I'm with robtg, a cold weld that did not hit the target by 1/8" or more.
Vibration (and over tourqeing, and perhaps a slightly misaligned engine mount) has taken its course.
And a possible difference in steel grades of the frame tube steel and cast steel engine mount.
I would not re-weld the mount on the front or rear of the mount as doing so could lead to the frame cracking (yuck)
Always, imo.

[robtg]

"I would not re-weld the mount on the front or rear of the mount as doing so could lead to the frame cracking (yuck)
Always, imo."

I agree.