No perfect portable toolset exists, as a minimum, you'll want a screwdriver (both slot and philips), a cresent wrench and some sort of pliers.

Other tools mentioned worth carrying include:

General Tools

• Leatherman
• Screwdriver (Slot/Philips); a Multi-tip or Kit is better
• Set of metric allen wrenches
• Small Cresent wrench
• Small Vise Grips
• Small Needle Nose
• Metric Socket Set
• Pliers

Spark problems

• Several spark plugs
• Spark plug tool with compatible wrench
• Spark gap tool/feeler gauges

Tire problems

• Tire inner-tube
• Tire irons
• Patch kit
• Tire pump or CO2 kit

Assorted replacement parts

• Bulbs
• Gas tubing
• Brake cable
• Throttle cable

Assorted other items

• Thread-lock
• Penetrating oil
• 2-5 zip ties
• 36-inches of bailing wire
• 2-stroke oil in 2-4 ounce container
• Roll of electrical tape
• Bungee cords in several sizes
• Rags
• Money
• Pepperspray
• Lighter
• Compass/GPS
• Cell phone

For endurance-trips

• Piston
• Rings
• Aluminum cleaner for scratched cylinder