You got it! On these engines, the barrel housings are fine but the barrels need to be smoothed a bit, not bad but a bit. It was really bad on my Tiger Shark 75 engine. In the case of the Tower Hobbies engines, the barrel was fine but the barrel housing had what looked like a bit of slag at the bottom of the barrel housing. I used one of the rubber tipped dremel bits to polish the housing out and they turn smooth as silk now. The throttle barrel on the new ASP engine is like an OS clone, never had to touch it. Very smooth turning out of the box. Can't wait for nicer weather to try them out. [8D]