Modern Vespa

With only 65 brand new miles a coworker friend let the brand new beauty drop while standing still onto its right side onto the pavement. It met the road and left a few scratches on the right side rear engine cover, broke the reflector and broke mirror stalk in it's socket.
My engine was not able to start again right away until 3-4 hours later -I let it sit upright until I had to go home then started with a little coaxing. I think it was flooded from the fall over.

When it was running again it was a faster idle speed than before the fall. I stopped and adjusted the idle screw back lower and resumed riding. Now upon de-acceleration it now does occasional backfire sneezes! Have I just slowed the idle too much, is the air filter messed up from flooding, the plug fouled or cables messed or carb out of wack? The impact was only slight and did not crease the cover other than surface scratches. When running thru the RPM's the engine runs fine still.
Any Ideas Appreciated.

:-?

Welcome. Ah the first scratch Sucks when you aren't the one to do it. You need to clean your air filter. Probably has gas in it. You can wash it with a mild soap and rinse with water. Be sure to lightly oil it after cleaning it. You also might have gas in the evap hose (emission crap they put on at the factory). You can disconnect the hose and that should help with your problems. I'm horrible with links but if you do a search for evap hose disconnect it should point you in the right direction. Step by step with pics.I'm betting these are the culprits. Hope this helps. Good luck