Check any in line fuel filters, the filter attached to the petcock, carburetor float settings, and blow out all of the passage ways especially the main jet. Hope that helps. There could be other issues that are causing your problem but the routine above would pretty much rule out fuel flow and carburetor as suspects.
I agree with the seafoam,,,,try that first, it's cheap and it will clean the carb for you but read the directions first.... and if that don't work you may have to take the carb out and check the high end jet!! :lol: :lol:
since the plugs were the last thing touched.....thoroughly check the wires for security and proper fit. Make sure they are on the plug securely. Also check the wires for wear marks. If the insulation is worn they could arc if close to metal. I had a dirt bike that this happened to.
found this info from another post.....by Mort:
"The sparkplug wires that goes into the coils are screwed in. If you twist the sparkplug wires counterclockwise by holding onto the wires, they will unscrew themselves from the screw down in the coil."
good area for a bad connection if not secured properly