Polaris 325 trail boss grinding
 

I have 325 trail boss when it get in bind it grinds badly I tighten chain it help some but still grind in bind but not as bad what could it be need help

Check the front sprocket teeth along for any stripped shaft splines on the sprocket. If it's ok probably the silent chain in the gear case is worn out and jumping teeth causing the grinding. Another way to tell is to pull up against a post or tree and give it throttle.If you hear grinding but it's not the drive chain slipping,then again probably the internal chain. This was a common problem especially on machines as they got older and also machines with high range only. Item #38. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse Hardest part is getting the gear case out and splitting it for this 40 buck chain.

ok but I did replace silent chain so it could be a sprocket thank u sir

I have one more question I bought a 110 cc japness 4 wheeler can't get battery stay charge run great just want charge battery can u please give me some suggestion on that problem sir and I got 2010 500 ho polaris it was idling I heard it start ratting in engine than died want start and no fire could that be timing chain thank u for your time sir

If the sprocket is worn out I'd replace it and the o-ring chain. Both probably have served their purpose over the years. Check any side play on chain links along with stiff links. That's usually the sign of a worn out chain.
On the 110 could be a regulator not keeping the battery charged. See if you are getting at least 13-14 volts while it's running. If not replace the regulator. If it's charging,then have the battery load tested. May have an open cell and not able to hold the charge from the regulator. You can check the timing chain easily on the 500 by pulling the square plate on the right side of the head.