After mounting the Polini performance variator (info in this thread ), I noticed that the bike began developing a jerkiness, especially on the low end. I swapped both the variator and the rear pulley / clutch out and it didn’t help. Turns out that the shaft sticking out of the hub that the pulley rests on is bent slightly. It’s hard to tell unless you rotate it. So word to the wise: If you install a new variator, make sure the pieces line up just right and don’t cause an issue.
Has anyone else experienced this problem?