1. This forum is the more updated and complete to get any sort of information about motorcycle travel. We personally found very usefull on our overland trips and we also contributed with our information. Check it out is a must

2. If you are looking for buy, fix, rent or spareparts for your motorcycle in Japan APEXMOTO  are the guys you will looking for .

I have personally see this shop when was opening few years ago.  I got help fixing my bike and tips about crossing to Russia.