I cant find any reason for Yahoo to rank my site on top 3 and Google to rank the same site, same keyword, on #65 position. Y ?
With the recent Panda updates you will rank in Google harder than Yahoo, they don't use the same ranking algorithm. With Yahoo you can rank using the same old methods but with Google you need to provide quality content and backlinks. If you want to rank higher on Google you will need to seo your website more in the natural way with social signals, videos, articles and provide quality information.
It makes perfect sense that a site may rank well on one search engine and not as well on another. All search engines use their own algorithms. With different algorithms, things are going to rank differently.
It's just a matter of search engine algorithm. Every search engine has it's own and using this algorithm every search engine determines in what position your website should be.
Every search engine has its own algorithms and also competition on search engine also change the results.
Because Google has lots of competition, lots of webmasters are trying to get higher visibility in Google search engine. According to algorithm of Google, some methods don't work at all for Google while it works for Yahoo, for example directory submission is still major factor for ranking sites in Yahoo search engine today.
There's a good likelihood that Yahoo & Bing use meta keywords and backlinks to rank sites. Meaning that keyword stuffing and directory submissions are a good means to build your authority.