Hey guys,

I live and do much of my riding at about 1,200ft. My friends cabin is at about 6,000+ft where I plan to ride quite a bit too.. There may be times where I go to 7k+ as well.. If I jet and tune for the lower elevation, how bad will performance degrade at the higher elevations? Can I simply adjust the air/fuel mixture when I get up higher to compensate somewhat?

 

Well, it will run richer up there (less air, right?) and will have less power, but I don't think with an elevation change of 5000 ft it will require a wholesale re-jetting of the bike. Fiddling with the fuel screw ought to help and maybe you could pull the snorkel from the airbox to get some more airflow. My experience is that I live at 7000 ft and my bike runs good here and good when I go down to around 4000 ft. Above 9000 ft I start to run rich and the bike bogs a bit, especially at partial throttle, i.e., on the pilot jet. I compensate by turning out the fuel screw. I probably could drop a size on the pilot jet since summer's here and my riding will be up high. Nevertheless my current jetting seems to be fine over a range of 5000 ft., maybe more.

I plan to try simply removing the snorkel and see if that helps high altitude performance. I currently have a KDX200 snorkel, the backfire screen has been removed, and I have a UNI air filter, so I'm getting lot's of air to the engine. Maybe too much. I also have a bigger exhaust header (FSW) and a KLX300 muffler sans butt plug. The bike runs great but maybe these mods make it a bit touchier about elevation changes because I seem to remember other post of people going from sea level to 10000 ft without much trouble. Maybe the problem is going over 10K ft. If so you have nothing to worry about! Let us know how things work out.

Edit: You could maybe take a smaller pilot jet with you if you have the time and inclination to swap jets. My rich-running problems at altitude are only noticeable when on the pilot jet, opening up the throttle all the way clears things up. And most of the time on trails I'm running off the pilot jet. I'm thinking your main jet should serve you well.