I just looked it up on ebay. Doesn't seem to be an outright scam, but I'd be a little leery about the seller. He's only got three transactions, negative feedback and one transaction aborted. Not a good track record so far.
How long has it been since you sent the e-mails? I usually give them about a day to respond.
Why I think it's probably not an outright scam:
1. There are plenty of pictures of the bike. Often, scammers will just pull one or two pictures of someone's bike off of the internet somewhere. They usually do not have access to more that two or three pictures of the same bike (also check the backgrounds of the photos to see that the bike was photographed in the same location, and not just random pictures of the same model and color bike). But this is not gospel. I have seen some scams with multiple pictures.
2. There is a VIN number listed. Most of the time scammers will not list a VIN number. In any case, if you have any doubts, you should run the VIN number through the state's DMV.
3. It is not listed at a low-ball price. When all is said and done, this bike will probably go for about $8,000. One of the biggest scams is to list a bike for a ridiculously low price to lure someone in for a quick sale. Of course, they have no bike and they'll try to get you to pay right away in return for such "a great deal."
$8,000 for this bike (remember it is still 2 years old and technically used) seems fair. But look into what the actual value of the bike is, if you don't already know, to get a feel as to whether you may be getting scammed.
4. The seller has completed transactions that relate to motorcycling/motorsports (Did sell some cars and had another bike listed.). Investigate the seller's feedback history and look for transactions/items that relate to motorcycles (if they're still available for viewing).
Apparently, many scammers hack into legitimate ebay users' accounts and list items to these accounts. If you find the bike is listed by "luv2knit" and you find only transactions for knitting and quilting supplies, you might be getting scammed. That is not to say that luv2knit can't also own a Gixxer, but in context of other suspicious circumstantial evidence, I'd stay away.
Also, this person seems to be in the buy/sell business, so it is possible that they bought this bike from the original owner or took it as a trade in. This could explain why the guy had it looked at and inspected. But this is a big maybe. If this guy doesn't respond to your e-mails and answer in a believeable manner, I'd walk away. There are plenty of honest, no hassle people on e-bay.
Hope this helps.