A few of my friends have started running 110 racing fuel in their four-stroke quads, will it hurt to run it in a two-stroke?

 

It won't hurt it to run it in a 2 stroke but if you are not running a high compression setup then it's a waste of money.

 

yup...the only thing you would gain is a little better smell and maybe a little cleaner running engine...but thats it
premium will do fine if you're stock

 

It wont hurt a thing, but i hardly recomend it. Higher octane fuel burns slower, and with that slow burn in a lower compression environmet, may cause you to lose a bit of performance, weather or not you notice the loss in power, depends on how well you know your machine.
Run as low as an octane as posible without pre-detonation.