Bad Idea. freak is right. It will make your quad way to heavy.
It also will give your frame the quality of rubber. Yeah ya might bounce off trees better, but I choose to go around them.
Plus the qualities of rubber would suck on a quad. It will scuff super easy. When it gets warm it will become soft. When it gets cold it will get hard, causin' it to crack or broke easy.
If you don't find the weight problem to be an issue I would go with bedliner. It is relatively cheap. Comes in a variety of different colors. Is easy enough to apply and is just like steel when it comes to protection. For those that find it might attract mud . . . You can now buy line-x without texture.
But for realistic choices I would go with powdercoat, anodize, or go high temp paint. All have pros and cons. But they all will look great and stand up to standard riding.
If you wallet is thin I would go a good engine-block enamel. It will hold a good shine and can be bought in a rattle can. If ya take you time with prep, do several thin layers, and allow plenty of cure time it will hold up for several seasons.
