A simple mod to the radiator.......

using some cheap aluminium mesh £1.99 (used for vehicle bodywork filling!).

 

Just offer it up for size,(fig.2) after removing the plastic guard on the front of the rad.

 

Then just fold the edges to fit. (fig. 3) 

 

Place it loose against the rad itself, (fig.4) and carefully replace the plastic guard - sorted! (fig.5).  No small stones through the large gaps in the grill.

 

I also cable tied the plastic guard in place to make sure it doesn't pop off. Don't worry about air flow....I rode like this through the Western Sahara with no problems at all