I like the looks of a Kitty, but I'm too large to actually ride one. Looks like a pretty good crack in that rear fender.....maybe from an impact. I have enough experience with cast aluminium to know it can be difficult. Sometimes it works well and other times it is a mess. Depends on what the alloy is and if it has a lot of undesirable stuff in it. Boat parts (jet boat and inboard exhaust manifold parts) seem to be particularly bad.