02 Sportsman 500   cranks but won't start.  Lazy spark when plug pulled out.  12.8 volts at battery, 11.2 volts when cranking.  New starter and battery.  Starts reliably with recoil starter used.  Changed coil, but still no go.   Suggestions??  

check the stator for dirt and or rust.

the magneto and stator contacts can get really rusty or dirty because of the way polaris designed them.

yank the cover and check them clean any dirt off, and lightly sand the rust off. you should get a better spark.