Will try to post some pics later, beautiful country out there.

Spent a week in Arapaho(SP) National park riding the Ranchers around. They had no running issue going from KS to approx. 9000 elevation where we camped. We even travel quite a bit higher on the ATVs. About the only thing I noticed difference in performance was that the top end seemed week. On grades that struggled to maintain 35 in 5th, where here at home, going up a good size hill has little or no effect on them (I'm comparing a steeper grade hill here in KS to a lesser incline in the Rockies, running on access roads, not going up the side of the mountains). I don't know if the power issue was due to the altitude or the Octane rating. Our first and second fill up was on 85 Oct. I wasn't even paying attention until the third trip to the pumps that the low grade gas around Denver was 85 octane and mid grade was 89. Our grades run 87, 88, 89, 90 and 91 here in KS. The owners manual to the ATVs say 86 or higher. I figured the low Oct. rating was something specifically for the altitude. I put 89 in for the last tank, but the week was pretty used up byt then.

There are some awesome trails winding every which way up there. My Rancher has the Warn 424 on it, I never needed the 4WD until the last couple days when it snowed about 6 inches. Other than that, climbing up the trail and rocks was pretty simple in 2WD. There was one instance where I had centered over a boulder and both the rear wheels just spun. I put it in 4WD to pull myself over. I could have backed up and drove across without stopping in 2WD had it been necessary.

My only disappointment was never needing to use either winch I had on either of the ATVs[img]i/expressions/face-icon-small-smile.gif[/img]

 

I don't know is you have seen my posts on venting the airbox lid for altitude changes, but it is a system that works very well. I have two TPI valves in the lid, and I open them as we ascend, and close them as we descend. Try it next time!

http://www.thunderproducts.com/tpi_valve.htm