Motorcycle Thailand has its own 'free' classifieds advertising, which has a good success rate of selling motorcycles. www.motorcycle.in.th/classifieds/index.php Of course you need to register and login to be able to post classified ads...
Another website popular in Thailand is dealfish.co.th and bahtsold.com, but the best idea for selling something online is to post your motorcycle on as most websites as possible.
By: fred (offline) Monday, 08 July 2013 @ 08:04 PM ICT
Some other sites:
mocyc.com/market.html everything about Bikes and Parts. The biggest I know. It's all in Thai.
thaisecondhand.com Also some some bikes for sale but not many
bangkok.craigslist.co.th/mca/ some nice bikes there for sell from foreigners, but not many.
then there are also other forums dedicated to some bikes, also many there for sale.
for example: www. superfour-club.com
Usually the owners will repeat their bike ads on most of those sites.