Mine just broke on me too. Its called the starter clutch and you should have no problem repairing unless badley worn. It consists of a plate with three rollers and three "pen" springs. really stupid type of clutch but can be repaired.
1. Remove oil pan, clutch cover, & clutch. The clutch "requires" a special socket from Honda, but I made it out of a 1" diameter steel plumbing pipe and a dremel. Follow the manual's instructions, but don't disassemble the clutch, just take it out.
2. Loosen the two bolts holding the primary shaft in and slide it out. The starter clutch is bolted to the primary drive chain gear, so the chain will keep it from falling out.
3. There are three bolts that hold the starter clutch to the primary gear - you need a Torx 30 head to get them out. You can see them through the hole the primary shaft slid out of. It's tricky, because you have to go through the holes in the starter gear to get to the bolts, and you have to loosen all three before taking it out because the bolt head won't fit through the holes in the starter gear.
Once unbolted it should drop out, and you can see what's wrong with it.
