I agree with jerry, if reliability is a big factor on a quad that is ridden often b.b. Isn't the way. Some people are dead set on an idea and won't budge.definitely get the head checked out even if u don't port it, valve job and have resurfaced.  Look in to an fcr carb swap, the stock carbs on the ltz will hold back your bb. Kit. Toss in a cam to complement that bb and you are good to go. I would also stay close to stock on compression ratio since its nit a race quad.good luck