Throttle Tough To Turn

I put a set of 29 mm smoothbores and new throttle cables on my Z1. The throttle operation is smooth, and the return snaps back on release. My problem is the throttle seems awfully tough to turn. I noticed when I had the carbs on the bench, that the throttle return spring on the 29 mm smoothbores seems to be quite stiff. Is this operation to be expected with new cables?

If the cables are new,and the throttle IS that tough to turn...I'd be looking for a "too tight of a bend" somewhere,or a kink in the cable(s).
Do You in fact have the carb-end of the cables in the holders correctly,with no criss-crossed cables?
You may have pinched a cable up near in the steering stem(triples),and You can't see it...hmmm...:whistle:

I have those same carbs on my 750 honda.
those return springs are like 3 times stronger than the stock ones.
maybe check that out.

I thought that spring seemed real strong. Maybe I don't have any problems with the cables. I will need the wrist of a gorilla!! Has anybody else noticed a big difference in throttle tension after switching to 29 mm smoothbores?