Might be a timing issue. The ignition pickup on the flywheel has been known to rotate, causing the ignition timing to be way off.
Valves could be out of adjustment, causing a lack of compression.
If you just cleaned out the carb, but didn't replace the needle and seat, that could be the problem. You may have cleaned out debris that was keeping the needle from sealing off, but now it may be stuck in there preventing fuel from flowing.
Check the carburetor boot (going from the carb to the cylinder) for cracks or tears. That will completely screw up the fuel mixture.
Just some ideas.
2006 Sportsman 450
27" Vampires on ITP Delta wheels
3 headlight mod
55w driving lights