I recently bought a 79 yamaha DT175, that won't run.?

you may have bad reeds or you did,nt clean the carb good enough, sometimes if it,s laquered up from sitting you may have to soak all the carb parts in chem-dip parts cleaner, (don,t put rubber or plastic parts in chem-dip it eats them) next, use carb cleaner w/ red spray tip right up against all orafices to clear them wear eye protection that stuff burns! if you don,t see anything coming out another area of the carb yoiu may need to clear the port with a fine wire, the best way is to use guitar strings, but be careful carbs are delicate. get a desktop magnifying glass it helps alot there are small holes on the walls of the throttle body interior barely visible clean those too, just do a thorough breakdown on a clean lint free towel keep your hands clean and you should be ok. now. if its the reeds, they cant be fixed they are between the cylender head and intake boot on the carb,if they look worn,stiff bent or chewy buy new ones. good luck! marcos9mm@yahoo.com