Hole in Crankcase

[Fladdem]

I did an enduro practise track day on the 25th of April on my CRM250, and due to recent circumstances, I've only just got round to looking at the bike.

On the track day, I was just getting into the swing of it and then I went to give the bike some beans up a hill, the split link in the chain snapped and the chain whipped and has put a crack in the crankcase. There is a bit of damage around it, but the section that's leaking is just a hairline crack, the other sections don't hold any oil.

What do?

Do you think chemical metal would work, if I roughed up the surface and put a smear on or get it TIG welded, which may be a bit difficult where it is, but could be done.
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Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[sickpup]

I am at a loss as to why a mechanic is asking this question when they should know the answer?

[Fladdem]