The targa is a relatively "modern" ped, and the HT coil and CDI unit should be in one unit (I've only seem them seperate on early 70's bikes and before) so I wouldn't suspect the CDI unit. A very common problem that no-one has mentioned is that the condensor might be bad. This will give you the correct voltage when testing the magneto, but will not make the plug spark. Condensors are very inexpensive (you can get one at Radio Shack for something like $3) and I would suspect and replace this before I do anything with the ignition unit. Like I said, this is a very common problem and I've gotten a few amazing deals just because its baffled a few folks. Best of luck and hope this helps!