I just fixed the Yager today. It was running fine, then cutting out, tach buried at 10k, and engine sputtering and slowing down, then engine light on when I held it wide open. I thought it was a charging issue and the bike was running bad because the battery was going dead. But while all this was going on, the meter at the battery sat right at 14. Very steady current. So I decided to change out the coil. It took me longer to figure out you don't have to take off any plastics to change it than it did to change it. I ended up using a coil for a different brand of fuel injected scooter that was $30, instead of the Kymco coil that I couldn't find cheaper than $90, and made a small change to the cap so it was easier to push onto the plug, and it runs like a champ. I ran the piss out of it for 25 miles, and not a sputter. If it runs this well next week, I'll consider it fixed. Hopefully this coil will last longer than the one Kymco uses. It was a little tricky to mount, and in hindsight, I should have just left the old one on and mounted this one somewhere else.
While I was going through the electrics, I found that some pinhead had disconnected the kickstand switch and coated the fuses with about a teaspoon of grease that looked like peanut butter. As soon as I saw that, I wondered what other "improvements" this idiot had made to the electrical system.