I wear a mesh Jacket and underneath is a cooling vest from CycleGear. The cooling vest is about $30, it works like an evap cooler. Soak the vest in water, put it on under a mesh jacket and it helps keep you cool, hell it works. Buddy and I left Bakersfield, Ca and headed to the coast 100 miles away. When we left it was about 75*f. On the way home comingt up 166 it hit 100*f plus. Our cooling vests were in our tankbags inside of ziplock bags wet with water from the night before. Rode home in the heat, cooler than when we had to stop and put the cooling vests on.
I hope I typed that right.