there are two should I say "main" overland routes from Europe to India. Most common is Turkey-Iran-Pakistan-India. There may be the problem with Iranian visa. The other is Kyrgyzstan-China-Pakistan-India. So for both you need the Pakistani visa. For that latter one, you also need to arrange entry to China, but it's a relatively short way inside China, so costs may be more tolerable. The Karakoram Highway is on that route, it is a famous destination in itself. And you naturally will need to cross some very high mountain roads on that route, so weather, especially winter, needs to be thought of. Eastern Turkey also gets too cold for bikes mid-winter, but otherwise that route is pretty much year-round. Summertime heat, as well as the monsoon season has to be taken into account further south. Edit. Turkey-Georgia-Russia is another bit, that'll demand some more research... I think it should be do-able these days, though, but you should be aware of where&how. You also have the option to go by ferry across the Caspian Sea.