I bought an X520 last Winter that had been hocked at a pawn shop for over a year. The guy never came back or made any payments on it so I bought it. It was surging when I got it out to test it today so I cleaned the carb and the surging went away. But when I went to put the float back in the bowl I realized it can go in either way and there is a difference in the offset of the tube where the pivot pin goes through. It will now run but stops at idle. I do not think a float issue would cause that but do any of you have a picture of the float? What is so aggravating about the float is that it has a dimple on one side of the float but thanks to Japanese engineering, they put one on the other side of the same float! So it can look correct either way. Talk about Murphy's law! One thing I got used to in aviation was that a new part could only fit one way. In the old days, mechanics would actually bend a preformed piece to make it fit the wrong way! So then the airplane builders put different fittings on each end so that it could not be done. This engine is a FD731V and a new carb is $425! Here is the blow-up of the carb. You can see the dimple in the float but if you flip it over there is also one on the bottom of the same float. It would move to the other side so I guess I will need to take the carb off and see if the dimple is on the side in this picture.