Modern Vespa

I have had this problem 2 times before.... When on decel, the exhaust has minor backfires (almost sounds like a roll of nickles in the cargo area). When idling the RPS surge up and down by 250RPMs. If you shut the key off and restart, all is well. Any ideas?

disconnect your battrie and then make sure its good and tight,

also change your plug put a NGK plug in if you have not done that and perhaps see if your exghust is loose at the Head

had many services this year all having that same issue lots of loose ends

and the plugs all looked bad around 2000 miles most were champion plugs

Below has been amended as I read it first as a Q relating to the carb engine!

Sounds like two things might be amiss here. The popping from the exhaust on deceleration on the GT (with carb) is normally down to a dirty Secondary Air System valve - if the noise it bothers you it's best to take it to the shop as it's not the easiest thing to remove. Does the 250 i.e have one of these?

Idle fluctuation on my GT usually means the carb CO needs tweaking - yours has an ecu so I reckon a code read could show up a sensor fault...

Hope that's of use!

Yeah I have about 2500 miles on it so maybe I will check the plug. It is fuel injected...