well I whipped off my seam X7 and replaced it with Shimano XT 10speed.

New inner cables, outer looks fine and was working just great before.

But the change up is just stiff as soon as I link the cable to the XT mech. Everything is running free. It was working before. The down shift is super quick too.

Any hints and tips?

Check cable routing – is the cable screwed in on the correct side of the bolt on the mech? If it’s wrong there won’t be enough leverage so it’ll feel stiff.

outer looks fine

There’s your issue. Fit new outer.

Does the cable run nice and straight into the mech, or is the cable kinked? Is it a clutch-type mech with a stiff clutch?

What bikeneil says +1.

Replaced the inners only on my bike the other day. Still stiff as you like so replaced the others too. Now nice and smooth.

Cable out is like new, the cable moved freely when not attached to the mech, def enough cable length too.

The mech is a dnya sys XT, I think it a clutch type.

No kinks…….possibly the outer, but I don’t think so. Any other tricks before I go and get myself a new outer?

http://www.chainreactioncycles.com/shimano-xt-m773-shadow-10-speed-rear-mech/rp-prod52299

I am assuming you have replaced the shifters at the same time…..you have,hav’nt you?

I found my error. My original cables were gore ride on. I have taken out the inner coated cable, replaced with a normal steel cable.

But until attached to the mech the cables runs sweet.