I'm in Argentina making my way to Chile. Yesterday after riding for a few hours the bike started to act up while going highway speeds - 100km/h - and I thought it was strange because I knew I had a half tank of gas. I naturally switched it over to reserve and it kept doing it - it was like a lack of gas...

I pulled over and tinkered around a bit. I was at 2600 meters above sea level so I remembered people talking about "rejetting" the carb. I figured I couldn't do that and did what I know how to do... I looked at my fuel filter and it looked fine then thought it may have to do with the air so looked at my air filter. The air filter was filthy so I shook it out. After about 15 minutes or so I had everything back together and I was back on the road and the bike was fine.

Today I also rode a lot, let's say about 400 miles, and it was fine... totally back to normal. On my way to the Chilean border it started to do the same thing that it did yesterday. I turned around to the nearest town and found a place to stay.

When it started acting up I was at 1800 meters above sea level so I figured it's not the altitude. I thoroughly clean the air filter yesterday and lubed it so it can't be that. I also assume it's not the fuel filter since the bike ran fine all day and only started to act up after a full day of riding... I have an extra one though so I can change it. In the lower gears it seemed normal, it was just at the end of the day when I was going about 95km/h.

I've been reading stuff online but can't find any fixes... some say it's a clogged screen in the tank, others say the carb, others say the petcock, some say the muffler. What should I look at and where should I start? Also, this is the last of my trip - I only have about 200 km left and will finish on the other side of the mountains in Santiago (basically the last day of riding in my seven-month trip:-).

I apologize in advance for my lack of knowledge but I figured that's what these forums are for - helping others when we need the help:-) Thanks in advance to those who reply.