okay so my piaggio nrg power 50dt always needs a new spark plug because they go all black and gunky and wont start. when i start it up in the morning and i ride it down the road at full throttle it takes time to get up to 35mph and its really smokey. i really dont know what to do, the guy who done my mot said he changed the jets but im not so sure,and not sure on the size either. thanks for any help
