Hmmmmm...seems like you should be able to turn at least in excess of 8000-8500 rpm with that prop. DON'T try to turn 16 grand like some folks will....."BOOM"

Is this a new engine? Not uncommon for a new engine to be a bit sensitive on the high end setting. If it's new...allow it some time and operate the engine as per the supplied instructions.

If not, some areas you may investigate are:

* All screws (backplate, carb, head, plug) properly tightened.

* Valve settings. (a valve not opening/closing completely will have an adverse effect on engine performance)

* Double check the fuel system. Pinholes in the fuel line, leaky fuel filters (they s*ck in this regard), incorrect fuel tank positioning can all drive you bonkers!

* Fresh Fuel. Who knows...a little moisture absorbed in your fuel pretty much ruins it. Crack open a fresh gallon.

Lastly...check your Tach. Make sure it's set for "2 blade" and to verify it's accuracy...aim it at a fluorescent light. It should read 3600RPM.

Good Luck! Let us know how you make out.