This is my first thread in this forum. I am new to ATV but I have done a lot of small engine fixes on mowers etc.

I purchased a used 2002 Polaris Sportsman 700 Twin. It was getting coolant in the oil so I have changed the water pump and oil seal. (I hope I have done it correctly).

I have also changed the intake boot at the carb as it had cracks in it.

After cleaning the carb and putting everything back together, I can get the ATV to start but it does not run correctly.

It revs to a high rpm and then will drop to a low rpm, idles fine for few seconds and then revs back up to high rpm on its own. Keep repeating this.

I have not found any one else having this issue so wanted to see if any one here can help me to solve the problem.

Thanks in advance.