YES 16fps is WAY to fast, im sure you already know that by now, but i will show you how to fix it by just getting 1 part. The AM 12t double sided sprocket
http://www.andymark.com/product-p/am-0736.htm. This will bring your gearing total down to ~8:1, as a driver i would enjoy a 8:1 reduction.
Hope this helped.