I once found a company called M-bike which was related to Sym, maybe you can contact them. The email I have is motor09(at)thaimail.com.
I believe they are located in the Prathumwan, Bangrak area in Bangkok...
I found also two motorcycle models they apparently currently sell, on the second picture at the bottom you can see a Sym logo...
I have a Sym Joymax 250, it go's like nothing you ever seen. The Sym Joymax 250 is a real sport-scooter it has a ceramic cylinder with top fuel-injection. The problem, the Sym Joymax 250 is actually 259.6cc therefore for most countries in Southeast Asia the engine is just to big.
Do you know if Sym scooters are sold in Thailand?
I have the HD200 Sym in Australia : 171cc 4 stroke 4 valve liquid cooled engine, auto trans, front and rear disc brake, 16" dia alloy wheels etc
Hope I can locate supplier in Bangkok or Chiang Mai, but so far without any success.
Hope you may be able to assist please.
Thanks and Regards
Mike
Perth, Western Australia