Oddly enough, on my '79 with the two full length cables, I "suddenly" (?) couldn't get enough free-play in my throttle cables. No matter what I tried.
I ordered a new pair, they were identical in every way to the pair I was replacing, but still, not enough free-play, which meant not enough cable exposed from the sheath.
I was lucky enough to find a place here in town that made cables, and I took one of mine in with me, and they sold me a length of cable, and the appropriate nipple-ends, comparing them to what I brought in.
He told me to get some silver solder, and that requires a hotter heat source than your typical soldering iron. So I used my propane torch.
It was a little iffy getting everything to stay in place during the soldering (don't forget flux), but it worked out, and I've been riding with those cables for over 2 years now. YMMV
Bottom line, though, I don't know why stock cables won't work on my bike. There is no damage to the carbs or the throttle...
