Honda Forman 250 Not starting

Hi everyone I’ve a 2011 Honda Forman atv and unfortunately 3 years ago I’m finally getting around to fixing it up . I let it run out of oil as the cap had loosened and it dropped out in a feild and I never new but anyway I’ve after putting a new starter solinoid new piston and cylinder head in as they all we’re looking bad I got the cylinder head and piston with the gasket and orings and gear for it . I also cleaned out the carburetor and for some odd reason when u go to start her up she’s tightening massively hard that u will need to get a bar to bar it over loose again . My question is has anybody got any ideas on what I can do next she broke down while I was driving it maybe’s it’s the transmission issue or oil pump ? If anyone has any suggestions please text me thank you