The tightness mentioned in the manual is for a new unrun engine and is quite normal for ABx type engines. This "pinch" will get less (and in some cases completely disappear) as the engine runs in. But this brings up a point, never turn over an engine straight out of the box just to play with it. Right then it's got the tightest "pinch" it's ever going to have and this pinch is an interference fit between the piston and liner. The oil that's covering all the surfaces is only an inhibiting oil to stop any rust and isn't designed to lubricate. If you turn the engine slowly through that pinch then chances are you'll hear the piston squeak. That's because there's more than enough time to squeeze all the oil away from between the top of the piston and the liner so it's running dry, metal to metal.

Only turn them over after you've put some fuel (or oil, preferably castor) into the cylinder and then turn it over quickly, not slowly.

Definitely use an air filter like the BruLine fine filter especially around sand. Dirt is death to an ABx type engine, ringed engines will handle it better.