Cruise control light flashing, wont set.

Flashing means there's a fault. I would check all the sensors on the bike. Make sure they are aligned properly and working properly. Clutch, both brakes, kickstand (unlikely this but still good to check ), and speed sensors on the wheels. Speed sensors seem to be a common culprit. Any misalignment with them causes all types of issues.

Also, check your brake lever slack. If your line is too tight, it can allow the brake switch out enough where it disengages the cruise control but not far enough to engage the brakes or the brake light. When you pull back your brake lever and you listen closely, you should hear two distinct clicks in the brake switch. First click is the cruise control disengagement, second is the brake light. If you're only hearing one, that's probably the culprit and hopefully will require some brake line adjustment or realig nment of the switch, lever, etc. I presume the rear wheel is the same but I've not personally messed with the rear brake.

If that does not fix and you're still under warranty, dealer can probably pull the reason for the fault.

If you're not on warranty and can't find any relevant problems, I would personally disconnect the battery for a bit and then reconnect it and see if that flushes the electrical Gremlins out before exploring further issues.

Finally, there's a section in the service manual for troubleshooting. Potentially this issue is mentioned and the recommendations on stuff to check. Check out the service manual and see if they address a flashing cruise light in troubleshooting. 

This is true, but that won't cause the light to flash, just won't engage. With him attempting to engage at 70plus as he stated, I guessing that's not the issue. I would agree that your earlier post with contacts would be the likely culprit. I would start with the new levers as they have been a problem for several in the past. The cheaper earlier levers did not have the dual contact switch.

If your absolutely positive that it worked previously after installing, (there were a few levers when our bike first came out that didn't have the dual switch required) perhaps that is what failed. Easy check of that would be to reinstall the stock clutch lever and start. No need to ride, as it will flash when turning on even in neutral as it should be doing now with the fault. If flashing with the old stock lever, then one of the micro switches mentioned in the previous post would be a good place to start. 

It would sure seem that the rear brake would be a great place to start. That being said, almost any fault within the bike renders the cruise inactive(with flashing light) but when cruise itself is operating and either of the brakes are operated, cruise shuts off but does not begin flashing until resumed. Keep us posted because someone has had the problem or will eventually as well. I had the cruise light flashing at first after my ecu flash with FTECU but was easily remedied by going into the diagnostics.

I just had an issue with mine where it did not flash but hitting the set button did not engage it. Checked all the brake and clutch switches and they worked fine. Seems mine was the side stand switch. I cleaned it up and it fixed it.

I just cleaned my side stand switch. Hopefully all goes well.

Shoot a little WD40 in the switch, you might have a little moisture in there.

Its the button being stuck. Kf it was something else, manually pulling the button wouldnt turn off the brakelight.

Yeah, I'm pretty confident that it's the front brake switch for myself as manually flicking the button in and out results in a temporary fix.

This was exactly the issue with mine. Replacing the front brake switch resolved my issue. And Yamaha has upgraded the entire part so that tells me something wasn't great with the original.