Idk what the EFI's will do, but I have had my sp 600 up to somewhere b/t 65 and 67. Thats topped out in a straight line one extremely smooth hardpack. One of those things you do once to see what you quad will do, dont plan on it again. My sp is fast from 0-40 mph, then it takes it a while to get to top speed.

 

I haven't even played with my displacement yet, still at 633cc. And, I get an excellent 0 to 50mph and good 50 to 76mph with my Prairie 650. I have common mods, but the Dyna FS CDI and clutch mods helped the most. It's fast enought for me now, but 50 to 76mph could still be better if I played with my displacement.

 

Scratch that just had it up to 67mph this weekend. I wonder if the weather makes a difference ? I could only get 64mph out of her in the wintertime. It was 85 on Saturday and managed to get another 3mph :^)

 

Some grizz odo read high... check on gps but still 60 anything is good on any machine and yes the air temp changes the way your machine breathes. Some grizzes here can go 67 and some can not too many varibles ie tires etc... have a fast one!

 

Ya next time I have it out I'll check the speed w/GPS.

 

For a one time, see what she'll do speed run, try pumping up the tires so they are much firmer than normal. Less rolling resistance. Put em back down when done checking speed.

 

My little Eiger will do really really close to 60, something like 58. Now, I only weigh 150, and that was on straight and level pavement, but that's pretty darn good for a 400. I'm not sure how much faster I would be comfortable going at top end, but it would be nice to be able to pull the front tires off the ground at 25! Maybe a twin peaks is in my future... maybe... but for now, 50-anything is fast enough.