JW, does anyone know how fast a stock yfz goes??

 

I was looking at a article that said something like 68 or 69 mph.

 

I have seen low 70's posted and in print. Seems about right to me.

 

the yfz is gear limited as 79mph, however you will never see 79 with the stock setup. Usually, depending on where you live its 73-74mph. I say it depends on where you live due to the jetting going to be that much farther off than it already is from the factory!
With the lid off, and the baffle taken out, you will have no problem bouncing off the 10,750rpm limiter in 5th gear, meaning you have met your full gearing potential, and should be running at 79mph, provided you have NO wheel spin!