CB oil pans are all die cast. Die cast aluminum has silicon added to reduce the tendency to crack. But, silicon makes it harder to weld. If your welder had ever welded a die casting before, he'd know that and should have been able to compensate.
On the other hand, being a very old die casting, Honda may have used more silicon than is usual today. So, even a very experienced welder might have had trouble with it.
On the other hand, being a very old die casting, Honda may have used more silicon than is usual today. So, even a very experienced welder might have had trouble with it.
