Modern Vespa

Here are the facts:
2013 Vespa LX 50 4T
270 Miles on it
Sat all winter.
Carb cleaned and serviced at shop.
New Battery
Air Box checked and cleaned.
Fresh Gas

Here are the symptoms.
Starts well, idles nicely until warm, then stalls.
Runs well for about five minutes with slight hesitation at full throttle.
After that, full throttle produces no power, feathering the throttle produces some power.

I'm thinking this may be n issue with the choke, at least that it feels like.

How can I test the automatic choke to see if I'm on the right track?

Any other thoughts for what's causing this?

Thanks in advance.

--Jeff

Welcome to MV

Do you notice an excessive amount if smoke from tbe exhayst? My first suggestion is to take it back to the shop that did the carb work. It clearly is not fixed.

Beyond that, you can test the choke by carefully removing the electric choke module. It's a screw holding a bracket over a cylindrical shaped protrusion on one side of the carb. It has plastic cover that snaps on. It's about 1.5 " tall, about the diameter of a nickle. After you remove the bracket, gently pull straight up to remove the choke plunger. The choke is very easy to damage if you wiggle too far side to side.

The engine must be cold to test. You will need to disconnect the 2 conductor connector, and apply 12v from a battery between the two terminals. If operating correctly, the plunger will extend about 1/4" with in about 60 seconds of applying 12v DC.

You cannot just turn on the ignition switch to supply 12v to the choke. Typically the 12v is only supplied with the engine running. If you understand how an automobile thermostat works, it's the same principle, like a blob of wax heating up to expand and causing the choke plunger to extend, and close off the choke/enrichment circuit of the carb.

Thanks for the quick reply. I'll give your test a try this afternoon. Also, there isn't any excessive smoke.