I have a 1974 Honda Xl125 exhaust pipe which has a crack in it. I attempted to weld the crack, creating a hole accidentally.
How should I properly patch the hole?
Here is a link to a photo for reference, including a 10mm socket for size reference:
Personally I would make a collar ie a piece of tube with a slit and slide it over the damage, then probably braze around the top, bottom and the join...
I would braze as the parent metal seems thin with lots of surface corrosion "dimples", so the collar should add some strength. If your welding is really good then you can weld it - but given the hole you created....
I wound up welding this back together with flux core.
The mistake I made was running a bead for too long, heating the base metal past its melting point.
The solution I found was to bit by bit deposit welding material around the parameter in short bursts allowing the base metal to cool between passes, After the hole was filled I ground it down with a dremel.