Matt if Sunny told you that the engines valve clearances may not be correct then you may want to take that into consideration.

Ask them for instructions on how to set the valves and to what clearances. Check this website for instructions on how to check/adjust the valves on similar push rod engines for comparison.

If they did not set the valve clearances correctly at the factory then running the engine cannot be good for it.

I would get the specs from Sunny and then check the valves, if you do not feel comfortable doing that yourself then find a mechanic, have them check the valves and the carburetor as well. That should be less then $100.00 in most shops.

Think ahead if you address the problem yourself and it is not resolved, they can blame it all on you. If you address the problem with a mechanic and it not resolved you have recourse.

If engines are coming over without the valves adjusted correctly then what else is not adjusted correctly?