How do you adjust the idle? When you put it in gear it grinds. On a Polaris 425 Magnum '97

Bad starter,replaced one on my grand sons not long ago,battery was weak,got it charged,still would not start,took starter off,it was locked up,they ordered one from Ebay,I installed,started right up,here's a site for a new starter,you can take off and take to Autozone to test to make sure.Also check the cable that goes from starter to the other connection.https://www.ebay.com/itm/STARTER-FOR-POLARIS-MAGNUM-425-4X4-2X4-1995-1996-1997-1998/262663578665?epid=8008132122&hash=item3d27f82429:rk:1:pf:0

you have a reverse safety like on riding mowers with deck engaged push and hold reverser button this link showes where and how it works --against bypassing a safety only video that showes the safety clearly 1995 Polaris Magnum 425 ATV Others Disable Reverse Override Function

check the hub fluid?

I'd go with a synthetic gear oil

broken drive belt?

Sounds like engine timing is way out mate take off right side engine cover and have a look at timing marks hope this helps

i dont no your model,but it is usually a screw on the carburettor.turn one way to idle up the other way to idle down

turn idle/lean down a bit and see what happens, then the gas may have water,timing, carb could be a few things

Trying to get the lights working on my 1997 2×4 400 polaris