I believe the motor your talking about is a 2 stroke, if thats the case.
Just make sure you use a good quality semi-synthetic TCW-3 grade or better oil.
Something like this is considered to be at least as good... if not better than yamalube. It certainly wont hurt to run a bit of it through your engine.
http://www.walmart.com/ip/Pennzoil-M...1-Gal/16401577
What you dont want to do is run any of the super cheap store brand 2 cycle oil in there (like the house brand for walmart, basspro, etc) those are not all tcw3 and definetly not synthetic.
If this makes you worry, then switch back to yamalube after your trip, and run some ring free in it to make yourself happy.