Cracked Engine Case!

[Dirteater]

I was washing my bike last night and found these cracks. They are where the swing arm bolt goes through the engine cases, chain side. It's a 2017 390rrs with 101 hrs on the clock. No big crashes or any thing that I can think of to cause this to happen. I'v checked the engine mounting bolts and they are good. Has anyone else ever seen this before?

[craigy]

Swing arm bolt tight? Swing arm bushes worn? frame cracked at the swing arm bolt mounting area? I looks like you are getting some flex of the swingarm bolt which is stressing the cases. I've seen similar on a KTM 400SC. Cracks were welded and no further cracking occurred.

[Muddaholic]

That sux man ... But it looks like it can be welded by a good... as in very good Tig Welder. Looks like you will have to pull the swing arm and the bearing. But again, it is fixable....