Ive got a gilera runner 180 with a 172 mallosi head! It runs fine all the time, but i havent rode it in a couple of days and it isnt starting, it has dellotor 25mm Carb with a choke, and it just isnt starting.. it has compresion and i changed the spark plug, what could it be???
you checked the obvious things: you deffo getting a good spark ? theres fuel reaching the engine ? your Reeds are ok ? you got plenty of compression ? you havent flooded the engine ?