I'm not sure what you mean here. What part are you refering to as a flywheel? An airplane engine usually does not have a flywheel, instead the prop itself serves this purpose. I think some of the Evolution trainer engines had sort of a flywheel on them to help add some rotating mass to help with idle and other stuff but that is all I have ever seen.

The sandpaper trick that deadey recommended works very well when you have a stubborn prop and spinner. Your setup though should be just fine without it. It is kind of tough to diagnose the problem without seeign it in person. I would take it to your field and have someone take a look at it.