Sjoerd and Ben,
re: Did the motor stop running when ,you say, you ran it out of oil? or did you ride it until the oil level went below the sight glass ?
I stopped to look at a map for 10 minutes, when I started it and began to drive away the it slipped out of gear with a very dry metallic sound and then wouldn't start again. I checked the oil level and it was completely dry. It took 1.5 liters to get it back to recommended level in the glass guage.
I'm not sure if I should drive it to Mexico City or just try to get (something- valves?) replaced now before continuing.
re: doo upgrade
I haven't done the doo-hickey upgrade. I have of course put tons of weight on the bike (3 large Pelican cases) and lots of very rough riding. You have given me more to worry about though!
Ok, so it could be either the balancer/tensioner or it could be the valves as the mechanic suggested, and possibly some damage from the lack of oil.
Thanks to both of you for taking the time to respond - I would really like my trip to continue with my trusted KLR companion...