I bought a Kymco agility 50. How do I find out what year it is? And also it Boggs down and black smoke comes out of the exhaust when I give it some gas? It starts and idles fine. Just can't ride it.

The manual is dated October 2014. Use 2015 as your date. Or ask them direct based on the serial number.

KYMCO Agility User Manual

https://www.manualslib.com/manual/972938/Kymco-Agility.html#manual

Advertising specs

Kymco Mobility Scooters Agility

Kymco UK https://www.kymco.co.uk > AGILITY-eq35fa
QUALITY, STYLE & PERFORMANCE! The new Agility compact 8 mph scooter offers high performance with comfort, making everyday journeys a pleasure!
Maximum Speed (Kph / mph): 12.8 Kph / 8 mph
Wheel Type: Pneumatic
Calculated Range (Km / Miles): 40 Km / 25 Miles
Turning Radius (mm): 1560 mm

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Question edited for clarity, changed 'carbonator', (a thing that puts bubbles in soda) to a carburetor (a device that atomises gasoline).

The new battery is fine, in fact 6 amps is better. It has more staying power and will start the bike easier in cold weather. It is better for your lighting as well. The problem is likely to be that your battery is not fully charged when you got it. Put it on a 2 amp battery charger for 8 hours.

These two adverts have 4 amp and 7 amp as suitable.

• YTX5L-BS GEL Battery for KYMCO Agility 50 50CC 09

  https://www.walmart.ca > YTX5L-BS-GEL-Battery-for-...
  
  YTX5L-BS GEL is a 12V 4AH 80 Cold Cranking Amps (CCA) GEL (Maintenance Free) Battery · Dimensions: 4.40 inches x 2.75 inches x 4.25 inches. Polarity: Negative on ...
  Assembled Length: 4.40 in
  Assembled Weight: 4.23 lb $51.95

Kymco Agility 50 Scooter and Moped Replacement Battery ...

https://batteryclerk.ca > ... > Scooter and Moped Batteries

Kymco Agility 50 Scooter and Moped Replacement Battery (2009-2016) · Voltage: 12V · Capacity: 7Ah · Cold Cranking Amps: 135 · Polarity: +/- · Terminal: B · Dimensions ...

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KYMCO Agility 50 Scooter Online Service Manual ...

https://www.cyclepedia.com/...manuals/kymco...scooter...repair-manuals/...
The CYCLEPEDIA PRESS LLC KYMCO Agility 50 Scooter online service manualfeatures detailed, full-color photographs and wiring diagrams, complete ...

If it only has 20 miles on it, take it back to the dealer.

WOW !
NUFF SAID . . .

Ckeck spark plug,batterie,put super fuel with a hight level of octane its gonna clean ir engine .

mcdevito75 here, The black smoke is gas, have your local shop check out the fuel system, Sensors, Fuel Pressure, fuel injectors all these can cause your problem, look for fuel system deals at various shops to save money, Sears, Pepboys etc.