Modern Vespa

just bought a 2002 et4 and the speedometer is not working. Only showing 790 miles, owner said it probably has around 850. what should I look for to fix speedometer?

Speedo cable for sure. Moderately involved, mainly pulling the glovebox and the headset covers.

The front wheel turns a worm gear called the speedo pinion drive. The bottom of the speedo cable connects to the speedo pinion drive. The cable runs all the way up to the speedometer and turns a gear inside the speedometer which makes it work.

The two most common failures are the speedo cable or the speedo pinion drive gear. I usually get inside the headset and take the speedo cable off the bottom of the speedometer. Then I turn the front wheel to see if it spins the speedo cable. If it does then you know something is wrong with the speedometer, which is an expensive fix. If it doesn't, you have a broken or detached speedo cable or a bad pinion drive gear, and they are pretty easy to replace.

We have all the above mentioned parts if you end up needing any of them. They're not on the website, so you'd have to call.