I currently live at 4300ft and ride in the mountains which are at a minimum as high or higher. I have a 2012 klx250s with a fmf Q4 and the top cut out of the airbox. This was previous owner I haven't done anything to it. It needs to be jetted that's one thing he didn't do.
what size needle, jet and washer would you recommend for my set up? With my KLR I bought one of Eagle Mikes jet kits.

thanks

thanks

 

I'm a little lower than you but regularly ride up to 8,000+ feet. I picked up a dynojet kit, kept the stock pilot, and did something like a DJ 125 or 128 main before going to a pumper carb. Other's went all Kawasaki using a KLX300 N1TC needle.
You'll get more input if you post in the KLX250 section: https://www.kawasakiforums.com/forum/klx-250s-71/

 

Thanks for pointing out I was in the klr250 forum. I swore I clicked in the right forum. Reposted in right place.