I have taken some very long rides.
The only "extra parts" I carry is a spark plug, and a spare chain link.
I always carry a extra tube and pump, and plenty of tools to do almost anything on the bike.
I did have a throttle cable break on a 140 mile trip one time. All I did was pull the shielding off and used the remainder cable as a pull string to work the throttle.
I do have a spare CDI and Mag which I got from....http://www.thatsdax.com/....but
I have never carried them with me on a ride but if you have them why not?
If you are running the stock chain that came with your kit....it is JUNK! It will stretch and stretch forever. Most of us will replace the stock chain with a good quality #41 chain........http://motorbicycling.com/f3/replace...hain-1139.html
I've been using my stock tensioner for five years and over 4,000 miles with no problems