Mark, what model did you get and where did you mount the servo? I have mine in the back of the battery box currently and have had the cable dressed out the left side. It then is curved around the overflow tank and eventually down and in front of #3. I have a small clamp attached to the hose clamp there to hold the cable housing in place, at that point it curves inward to a stationary point where the end is fastened. Beyond that is the beaded chain attached to the left side of the actuator arm for the carbs. It has worked for 10-12 years now and I'm thinking I did something to the installation when I pulled/replaced the carbs. Hoping I can get it working before traveling this summer.
John,
I guess it was the Rostra 250. Put the servo/control box behind the battery which I moved fully forward and shimmed it there with a small block of wood at the bottom of the battery box. I cut out the dividers in the box so I could move things where I needed them. Rerouted the heavy electrical cables at the starter so I could move the battery more forward. The throttle pull cable goes out the right side and curves forward inside the plastic cover. In this pic, it's routed outward past the PC-8 fuse panel.

It goes past the starter and makes a big 270° loop to connect to the throttle linkage between #4 & #6 runners. I made a bracket to hold the end of the cable housing in the right place. The bead chain and the bracket I made:

BobB's write-up of the Rostra 250 install, with my notes and pics appended:
http://www.valkyrieforum.com/bbs/index.php/topic,86066.0.html