The comment about "how to repair a shift lever" etc. is dead on the money. The real types of repairs are the ones where the bike gets kicked over and something breaks...better to not be stranded than to worry about a dropped valve. (because by that point your ride may pretty much be over...)
I keep a length of wire coat hanger in my bag - it's been used for exhaust bolt replacement, and other "through bolt" replacements on the road where a bolt has rattled free.
Mini-Vice Grips are a good quick replacement for a broken lever.
My license plate contains four different bolt sizes and nuts - all sized as replacement bolts on the bike.
The other key is "KNOW YOUR BIKE". Know what bolts are sacraficial if you need them. If you can pull a rear passenger peg bolt to replace a failed bolt elsewhere on the bike, then do it. (*Assumes no passenger of course...)
We all know about zip ties, duct tape and epoxy-steel. Why not add 2' of safety wire? A hotmelt glue stick can be worked with a lighter or match. How about a bit of small velcro strap or lightweight cord in case a saddlebag fails or you need a bit more tie-down cord?
And don't ever forget to stash an emergency credit card somewhere on the bike or person. Worst case scenario in the USA today typically involves a phone call (*Haul Road only partially excepted) and a tow-truck and a flight home...
2011 Yamaha WR250R
2012 Ducati Monster
2007 R1200GS (Sold)
IBA # 20880. STFU and Ride.