I’ve been out riding off-road a lot lately. This week I’ve been riding up over 8,000 feet and wow is it exhausting. The terrain is rough and the oxygen content is low.
If you want to ride up this high and have a carbureted bike you’ll need to rejet. Some bike are more picky about oxygen levels than others, but for my KTM I had to drop 2 sizes on the main jet, 1 size on the pilot jet, and I lowered the needle 1 clip. I’ll put together a good guide for altitude jetting across different motor types shortly.