I had trouble with that at first too because I read that it should taste sour and I found the Kefir sweet. From being on the body ecology/candida diet and not having any sugar, my sensitivity to sweetness is heightened. I put my kefir out for another two days with the results being the same. It does have a sourish but sweet taste - that's okay, it how it is supposed to be.
You know when the kefir is finished when it is a little cloudy (like lemonade) and has some scum (like the film on a soup) on top. I have tested it from 1 - 4 days and there is little difference. 1 1/2 is what it takes to complete.
Give it a try and see how it works. Let me know if you have more questions.
Oh, to open coconuts (just need to open the end slit), I cut off the top 1/4-1/2 inch and pierce the long slit with an oyster shucker. Works great!