|The Symba's Secondary Air Injection System ("AIC")|
Now that so many Symbas are in use in the USA and have been for almost 3 years, some "experience" is developing regarding certain aspects of the bike.
More than a few Symba owners have reported a problem with the engine not starting, or not running smoothly. One of the first solutions promulgated on the SYM Owner's Forum was the air-mixture adjustment screw on the carburetor (or, carburettor, if you're British).
I ran into this on my daughter's Symba. Right out of the crate, it was reluctant to start and it ran poorly - rolling on the throttle resulted in engine cut-off, requiring quick action (pumping the throttle) to avoid stalls. The solution was to re-adjust the air-fuel mixture - a simple procedure on older bikes such as my '69 Honda Cub, but made a PITA on the Symba by the EPA-mandated shaving and sealing of the screw. I wound up purchasing a whole new screw and removing the old one by drilling away the resin sealant and using an easy-out tool (since the head had been shaved off). If you feel you need to do this, see the info here.
Now Symba owners are starting to discover other problems - bikes that suddenly won't start, even when the engine is warm, and particularly after filling the gas tank, resulting in the sorry spectacle of a Symba being pushed home on the side of the road, like some POS Znen or Wildfire bike that also rusts over if you put it in the same room with a damp rag.
The problem seems to be, again, over-zealous pollution control subsystems. The Symba has two of these encumbrances: the Secondary Air Injection System ("AIC") and the Evaporative Emissions Control System ("EEC"). Some riders who have encountered engine starting woes have removed one or both of these, which takes only novice mechanical skills.
If you're having the problems described, it might be worth considering going this route. For more info, see these entries in the SYM Forum's Symba section.