Determine what type of plastic it is, then determine the appropriate adhesive for it. There are a lot of plastic repair processes, including "welding", 3M has a whole line of repair products used primarily in the auto/motorsport industry, Duramix is one product.
I've welded ATV plastic on many occasions, we spent many years racing MX on Quads...
It won't look perfect, but I would probably weld that crack, really the only way to get it to hold, the adhesives/epoxies will require something to bridge the crack. When I welded ATV fenders I would "stitch" the crack back together with safety wire, then weld and remove the stitches as I went along.
Obviously a lot of effort, might be better just to replace it?
Last edited by shoot summ; 08-23-2016 at 09:14 AM.