I have 2 pro 48s. Had problems with both, until I took it to the new hobby shop in town. I had assumed both LSN would be in the ball park from the factory, NOT! one was out almost 8 turns the other over 6. I played with both needles and wasted 2 gals of fuel. Never thinking that the high speed needle physically effects the low end needle. So if the HSN is at the recommended 2 1/2 turns the LSN is no where near seated. OK long story short they both run like champs now. They don't make quite the power some of the others due but I would recommend them for someone on a tight budget that needs an engine for a trainer. BTW one has the new carb, the other has the old. Always happy to help if I can. Garry