I am just about to leave SE Asia after five months. OK. Best is to have a carnet in SE Asia and to show it at the borders, mine was even stamped into Vietnam. Five days ago I met a Brit and he imported his bike on Bkk airport without a carnet, they stamped it into his passport, but for Malaysia he used the carnet.
Take the carnet from home and use it, even if it is not valid for the country, if you have enough pages and if you don't want to sell the bike over here.
Greetings from KL, and if you need more informations about border crossing just send me an email.