Was the new thermostat OEM?? If not, I would pull it out and check it per the manual. Actually, even if it is OEM I would pull it out. Sounds like it may be sticking in the closed position.I have a 2014 Honda foreman and within about 15 minutes of riding it'll start to over heat. I have the radiator relocated . I've replaced the thermostat and cleaned the radiator until it's clean as a whistle. I also checked the water pump on it, it seemed to be fine all the props were still in tack and is wasn't seized up . The fan comes on and will run pretty much the whole time. I did notice the hose coming out the top of the radiator will get hot and the hose on the bottom would be much cooler . I don't know what else to check . Anyone have any ideas . Thanks
I'm assuming you used the correct size tubing when you relocated the radiator?
Did you bleed the system well after you relocated, refilled the radiator and reserve tank? Air in the system will cause overheating.