The gay trike also only has one wheel in the front making it stupid light in the front and shitty handling.
If you want a quad to hit 90mph, you must first gear it to do that. If you can hit 7500 rpm, run 21" rear tire, a 15/40 sprocket will hit 90mph on a lt500r. Next issue is having the power to attaching hit 7500rpm in 5th gear.