I solved mine by replacing a worn speedo cable that caused a "wobble" in my speedometer needle. Evidently the erratic information delivered by the not-so-smooth cable caused the cruise to not know if it needed to accelerate or slow down. The cruise would average a speed, but not hold it. Now it is dead on and smooth.
It could be a couple of things...but really does depend on what the issue is...
1. could be the speedo cable needing lubrication
2. could be any of the micro switches not properly engaging
3. could be the brass bushing on the clutch lever being worn and needing replacement
4. could be your right foot riding the brake
If "not stable" means holding speed and stays on cruise, but hunts, this is what mine is doing. I have a bounce in my spedometer from 0-20 mph. I had no spedometer a few months back, but I replaced the rubber thingy in the gearbox on side of wheel. Rubber nubs were torn. I like the idea of replacing the cable. Sounds like this would be my fix.
What is normal for cruise control? I used my cruise control for an hour or more over the weekend. When I first used it I thought it hunted for keeping a speed. This weekend, I watched the RPM and speed, but they were solid. I feel torque going on/off and thought this wasn't going to give me good gas mileage. After using it for over an hour, either I got use to the searching torque or it fixed itself. What is normal? A car has a smooth transition and I thought the bike was harsh. Now I got use to it or it did smooth out. How would someone explain their "smooth" cruise control? I first explained that mine was hunting, but the RPM and speed looked smooth, but my butt felt the torque on and off.
For me, I just changed my filters. The previous ones were not as people described old filters would look like. I just bought the bike in August, so I had lots to learn about the bike and what was/wasnt done.