Re: strong mounts for motorized beach cruiser
Yours is not the first report of Micargi frames cracking. Use the search. key word, Micargi, and you can see and read what others have found.
Your fix sounds strong but keep an eye on the other critical places, (what isn't critical on a bike?) and make sure nothing else lets go. Be careful.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"