I just purchased a new 2003 piece of equipment with a robin engine. It sputtered at high rpm's so I went through the process of checking spark at all rpm's and was o.k. pulled off air filter thinking it might be a defective air cleaner with too small micron size......still sputters. Pulled off carb and cleaned the air bleed........still sputters. Ran the engine and turned off the fuel and after 3 seconds it ran great so I say o.k. the float is high or the viton tip on the needle valve is bad from having fuel sit in it for 2 years. Pull out the needle valve and that was o.k. The float is plastic or nylon and is not adjustable and it had no gas inside it.....so I am thinking that the float is defective even though it floats when I test it. Have you guys ever had a bad float in a new piece of equipment? What else would cause this problem? It is a fixed jet carb also. Thanks for your input....... Pete D.