A little late, but some guys have now been caught out.
On 1st December 2016 a new visa policy for entering Thailand came into force.
Specifically if you are entering at a land border crossing then you can only enter twice a calendar year with a “visa free entry” on arrival for a 30 day stay.
More than two entries in a calendar year & you must have a visa in your passport before attempting to enter. No visa, sorry cannot come in.
Riders from Malaysia who come frequently will be most affected, and the solution for frequent riders is to get a multiple entry tourist visa for 5,000 baht.
If you get stuck in Laos or Cambodia trying to ride back into Thailand, then you need to get a visa from the Thai embassy in Vientiane or at the Thai consulate in Savannakhet, & in Cambodia from Thai embassy in Phnom Phenh.