Modern Vespa

Hi
New to me 2008 S150 - loving it so far!

6,300 miles

New battery 1 month ago but now wants to start slow and seems like not 100% engaged

Charged battery and seems a little better but not 100% right

Thinking bendix or possible voltage regulator??

Anyone rebuild the starter or just replace?

Anyone have testing procedure to check stator output?

Any ideas or thoughts appreciated
Thanks in advance

First, I would measure the battery voltage: just after charging, at rest, and while starting. Measure the voltage while the scooter is running to test the stator and regulator output. Or, take the battery to a car parts or battery store and have it tested under load. Eliminate a weak battery as the cause before you get into bendix, stator, regulator, etc.

How was the starting right after you got the new battery?

You check the charging system by:

Measure voltage at battery terminals at rest ~12.6V

Start scooter and measure voltage at battery terminals 13.2-14.5 V

Rev scooter to about 3k rpm and measure voltage should not go over 15V

If really high, your CEL should also come on.

If levels not obtained you can verify stator output by unplugging stator. Should be a plug under front of pet carrier with 3 yellow wires going into it from stator. Check condition of connector as some of these have known over heating due to high resistance connections.

Measure ohms of each stator coil. should all be about the same ~0.1 ohm.

Start scooter and test for voltage output. This will be AC voltage around 60 volts.

Even though brand new, you can take the battery into a shop to be load tested. It is possible to get a bum battery.

Please report your findings back.

not all batteries are the same.

what new battery did you install, make , model, specs?

highly doubt anything is wrong with the starter with such low mileage

When was your last transmission service? Could be a gunked up starter bendix.

I had to replace the starter motor in my '09 S after 12 years and not so many miles. It seemed like the carbon brushes had simply gotten crumbly and dusty. The difference between the old and new starters was…well..startling.

Scooterpartsco's price was reasonable compared to the alternatives, as usual.

I took the old starter apart to replace the brushes and found it very challenging. The result was far from adequate, even for a backup. There is a YT video from somebody showing how to do it but considering the replacement cost, the juice isn't worth the squeeze IMO.

As long as you're in there you might as well replace the Bendix (or Sprag gear) device. Those are quite inexpensive.