Just bought a '91 Tw 200 today. Not familiar with them and was wondering if there is anything I should expect or watch out for on a '91.
The 91 model is a very solid machine. No specific problems that I'm aware of. Just do a tune up and a service. Change the oil, clean or replace the air filter, change the spark plug, check the valve adjustment. If in doubt, take the bowl off of the carburetor and check it out. Lube the cables and levers. Check the brakes, check the chain and sprockets, replace the tires if needed.
There is one thing that all TW's seem to suffer from. Make sure the clutch is adjusted properly and that it's return spring is in place.