I am having problems with my DA 50 and looking for help. It has been running fine for about three years with no problems. At the end of last season it began to have problems sputtering on the high end. I sent it back to DA for service and they updated several items on the engine. I just placed it in a Yak 54 with the DA tuned pipe. I was able to get the engine adjusted to a smooth idle and transition; however, when at full throttle it would not run consistently. It acted like it was too lean so I continued to richen the high end. It improved but I ended up eventually backing the high end screw completely out and it still continued to act this way. I never had any problems until now and am looking for some help. I called DA and they said it sounded like fuel draw issues; however, I am using the same 1/8 ID fule tube that I have for the past three years.

The engine was completely reconditioned by DA and this was the first time out of the box. It has a new ignition, plug, DA updates, etc. I checked the fule with a friend flying who had no problems to help narrow down the possibilities.

Any suggestions on why it would sag and then begin to surge at full throttle?