I've purchased some of my parts from Live Fast Motors
. Their clam shell sprocket adapter and spring loaded chain tensioner works great. They ship fast, so if you have a week before the trip, give them a try. As for carrying spare parts, make sure you carry extra cables with you. If the throttle breaks, you're not going anywhere and the reverse for brakes. Even on short trips I carry a bottle or 2 of 2 stroke oil in case. Carrying enough tools to fix anything on the bike is a no brainer. We don't want to see a post saying they had to push their motorized bicycle back all 100 miles. Good luck!