2000 xp surging at full throttle

[azsxr]

So I got this 2000 xp that I just got running. I rebuilt the carbs and changed the fuel lines.it ran pretty good pulled alright up to 6850. After a few min it would only get 6000-6200 and sound like it was surging but didn’t feel like it was surging as far as I could tell.
I opened the high adjusters a 1/4 turn out and no change.
Any ideas

 

[Venturian1]

When you rebuilt the carbs, did you replace the fuel pump check valves? check sync of the two carbs throttle plates? test the fuel selector valve?

 

[mikidymac]

I would check compression to be safe.

 

[azsxr]

Yep I changed everything in the carbs and they are in sync and it was a new selector valve but I just bypassed it. I’ll check the compression this weekend.
Thanks to you both