Running poorly & electrical

The current problems are:
1) Electrical (switch is broken and tail light is wired wrong)
2) Bike is running poorly (kill switch was likely causing this)
3) Clutch not operating correctly
4) Scraping sound made when you walk or ride bike

The brand new switch should resolve issues 1 and 2.

I emailed Paul S. and asked him why a cracked/grounded horn switch would affect the bike and cause it to run poorly. I understand why is screwed up the electrical, which was one of the four problems with the scoot. Paul knew when I pulled up something was wrong with the way the bike was running and I wanted to know *exactly* why.

Response from Paul S.:

Well, I've ridden/worked on hundreds of Vespas at this point. It is pretty easy for me to hear when they are not running right. You should also be able to notice the difference with the new switch. It will be very obvious. When they are running well, they have a nice smooth idle. Yours was misfiring, and acting like it was dying. This can happen with poor igition or with poor carbueration. When you first rolled up, I thought you had an ignition problem. In a way you did. The kill switch was essentially "almost" on all the time. The broken switch made it so that the kill switch was just about engaged. That caused the igitition system to be working poorly. Once I pulled the switch off, the motor idled like a champ.

I should not have to pull the motor all the way apart to get at the clutch. I'll just have to pull off the rear hub and the clutch cover. Depending on the source of the scraping noise (when the scooter is rolling around), I may have to delve further inside the motor. I doubt it however. I suspect the scraping noise is coming from the rear brake backplate. The only way to be sure is to get it up on the lift. Luckily both of your issues are in the same area, so hopefully I can fix them both at the same time. Unfortunately I've been so busy with the family that I have had virtually no garage time in the past few weeks.

A special thanx to Paul for his expertise. He diagnosed the problems very quickly and was correct. If you remember in previous posts (years ago now) Christopher Markley said that the backplate scraped at the rear hub because it is either thicker with powder coat or it is missing a spacer, though when he looked in the parts diagram there was not an additional spacer.

Request from readers/SS180 owners: Besides the parts book diagram, does any one have pictures of their assembly of the rear hub / backplate showing all spacers and hardware for me to reference against? If so, please comment.

I have asked Paul to contact me when he knows he will be working on the bike so I can meet with him and learn from him. He is far more experienced than I am. He has a toddler, so his schedule is just like mine . . . around our toddlers.