Are these bikes limited to 70mph because of the stock cdi. At wide open top end speed my bike doesn't sound like its toped out in the rpm range.

 

I can get to 76.4 mph (GPS) on the dry lake beds out here, with the mods listed below.

 

Oh, and I don't yet have a cdi.

 

I live in arkansas, with the dmc duals, epi red spring, and 138f 142r jets, I can only run 70mph on a 1000ft drag strip. This is without any air box mods. Is this a normal speed for my mods?

 

That is about right for your mods. I was on a dry lake bed. I hit my top speed at about just under 1 mile or so. I can get to 65 real fast, but after that, it is slow at gaining speed.

 

The V's, like the prairie's are limited by the size of the clutches, to small, run out of gear.

Look at your primary clutch, the front one, 1/2" inch of clutch at the top is not being used. You can tell by the belt marks.

Get some airbox mods to go with the duals, jet up and get rid of that red spring. At least you'll be quicker.