I don't know the exact temperature, but I can tell you there was snow on the ground and I couldn't pull in the clutch on my kz440. I mean, I could, but it wouldn't release right away. It took several minutes. I rode across town, to pick up some girl, and bring her back to where I was. I could shift without the clutch, no prob, but I had to kill the motor to stop and start it again in gear to go.

Temps here got down to -17, maybe I should have ridden around the block just to say I did