I went looking for a key blank for my first gen Venture.  I had read that the ILCO YH46 X120 was the correct blank but there is a better choice.  The keymaster at our local ACE Hardware had the X120 but said the HICO 11010 YH50 was a better match for my OEM key.  Of course, it has a flat head, not the Yamaha plastic logo one, but I was looking for one I could stash somewhere on the bike so no problem.   
ACE UPC # 029069706852.  Price = $2.19 plus tax and that includes cutting the blank!