Need help: Upgraded from 9 speed Ultegra shifters to Dura Ace 7800's (new)
 

Had a bad left shifter that jammed up a lot. Ordered a Ultegra 10 speed cassette and my LBS had a brand new pair of NOS Dura Ace 7800's. Spent a couple hours and installed everything exactly how I wanted it. Ran new cables, new outer casings, and here we are. The front rings shift perfect, and they are the ones I was concerned about with the 9 speed derailer. The rear is another story. IF I am in the front 39 and rear 12, and shift to 13 and then 14, I get delayed shiftts or no shifts. IF I tighten the inner cable, it will shift fine at the top end, but then when I am in the 25 and 23, it will hesitate goping from 25-23 and 23-21 and ride in between the cogs. I'm taking from Peter to give to Paul. Help....

did you use the metal caps on the ends of each cable housing? if not, that could explain your soft shifting.

Recheck your cable routing, make sure it is correct. Especially under the bottom bracket. Is the loop on the rear derailure large enough? I t sounds like you have some extra friction on the cable some where.

Edit: I didnt see any mention of you installing a 10 speed chain. You need to run the narrower 10 speed specific chain with the 10 speed cassette.