"The other main track/Honda testing facility is just outside Tokyo in Nagoya called Suzuka Circuit. If you check the Honda website you should be able to get directed to there also. I don't know about an actual motorcycle "shopping district" although there are a lot of motorcycle related industries in that area..so it might be possible."
Hey sorry I came to this late but sounds like Ichiban has you sorted already with the Motorcycle museum - Id definitely make a trip to the Honda Museum as I still havent been myself! I did however go to the Toyota Factory Museum in Nagoya (there are 2 places you can visit there) and they are both worth it! Another good museum to go to in Tokyo is the Tokyo Edo Museum - very comprehensive review of the Meiji period (1868 era) - and near here is an area famous for chanko nabe (what sumo wrestlers eat - very good!.
Motorcycle stuff -Nagoya - near Nagoya station is the Yamiya shop where you can drool over CB750K0s and buy tanks, pipes, anything really - check out directions here:
http://www.yamiya750e.com/catalog/default.php?language=enand my old thread about it here:
http://forums.sohc4.net/index.php?topic=13264.0Some general info about riding in Japan in this thread from a previous trip.....
http://forums.sohc4.net/index.php?topic=13817.0and here....
http://forums.sohc4.net/index.php?topic=2230.0You can rent bikes at most motorcycle dealers - prices depend on size of bike. I rode from Nagoya down to the Pearl Coast (Shima Hanto - also a train ride from Osaka) and to Koya San (great twisty mountain roads here). Also been to Bandai Koegn, Ise Hanto (near Tokyo) and rode the Suzuka Skyline Drive (this is the one near the Honda Suzuka race circuit).
Some You tube videos here of me being a passenger in Japan....riding the Izu skyline
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Motorcycle shopping - Tokyo - Ueno district next to Ueno station - LOTS of bike shops here with some bargains to be had - take your wallet and a translator!! Very cool stuff.
Lastly...some tourist tips.....
Osaka - great place at night - go to the Ebisu-bashi (Fishing bridge) and see all the neon signs from here - better than Tokyo! And check out the local yakazuka trying to pick up women ;-)....some great seafood places here - try the seafood okonomoyaki -local specialty. Since you are in Osaka you have to visit Kobe - great place to see turn of century European Houses on the hill and take the cable car up to the top of the mountain (take the one on the far right -at night is best - romantic spot and you can see the lights of the city below). If you get the chance go to Kyoto - its all good...lots of old shrines....worth seeing I think.
Yokohama - if you get the chance go here! Short ride from Tokyo - take the worlds fastest elevator - very cool at night. Nice stroll along the harbor and take a harbor cruise for perspective...chinatown here is good and famous noodle shops if you can find them.
Ok thats it for now...if you want further details/tips let me know. You are going to have a great time! And get the Japan rail pass - very economical as the Shinakensen really adds up - e.g. $110 (one way) from Tokyo to Nagoya - takes 90 mins. A Pass will make it cheaper.
Food costs - same as US and sometimes cheaper (for noodle shops etc) - of course if you want a steak/Kobe beef be prepared to get a mortgage to pay for it ;-)....Convienence stores are great for lunch - Bento boxes are $5 and very healthy/filling. But Im sure you will be well taken care of by the family/friends.
Dont forget - "chisai biru o kudasai"

cheers
Andy
P.S. For more general info - this is a good site -http://japan-guide.com/