Modern Vespa

Hi, recently got my PX 125 serviced and got an expert to look at and set up my carb. Have to say it goes like a dream now and plug is showing a good colour.

Today though, (bearing in mind the weather is rather warm) I turned the engine off after a ride for about 5 mins. When I started engine I revved it up it almost died 1/4 throttle but I managed to 'rescue' it by turning the throttle further. It would normally do this with a cold engine. After less than a minute of riding the problem cleared so I don't believe the carb is set too lean on the idle. I'm reluctant to adjust anything as the bike goes beautifully otherwise having been adjusted by a renowned and trusted scooter mechanic.

A similar thing happened when I forgot to turn the fuel tap on and the bike cut out. Once I had turned the tap on I was getting the above problem for a few mins. Any thoughts?

Either the pilot jet (tiny hole in the end) is restricted somehow or maybe the mixture screw is not adjusted not so well.

Strangely hasn't done it today. I think I'll give the pilot jet a good blast with carb cleaner. Thanks for your comment

My scooters manifest similar symptoms only when the fuel in the gas tank is about to run to reserve. there is a fine spot where you can run with the fuel cock open or on reserve and it can run well or bad on either setting and viceversa.

iT happens more often that what you think. You can also look for bubbles on the fuel line as well as small cuts on the fuel line or even a lose fuel line, all of the above will cause the same issue.