I think they were six-speed, but dont quote me on that. As for inherent problems? Do a compression check, look it over real good, be sure the air filter has been doing its job, and you'll be good to go as long as these areas check out. Just about all the problems with a 2- stroke can be traced back to lack of lube, dirt/sand ingestion, and/or overheating.
Check the basics and as long as it has been maintained, I dont forsee any troubles. Then again, Im speaking generically since Ive never owned a tri moto. Somebody else who has more experience than I with them please feel free to chime in.