Same right knock sensor issue here. I have an '03 ST1300 Non-ABS but it DOES have an electric windshield (The original owner, a Honda Exec, had it installed...more money than brains I suspect). The problem just started for me at 49,000 miles (78,857 km). F1 light comes on at 4,400 RPM's without exception, hot days or cold. I live in Seattle so most days are "cold" 75 degrees F down to 45 degrees F (24C down to 7C).
Took off all the Tupperware and replaced (spliced in new) the wire leading to the knock sensor. The previous wire did look as though it had endured a lot of heat. Wrapped the new wire in tinfoil, then wrapped it in heat resistant tape. Made certain it stood off from the header as well, although it never seemed to be touching.
Now, oddly, it won't come on as regularly at 4,400 RPM's, but it still comes on. There seems little rhyme or reason as to when it comes on. Sometimes I can ride all day and it won't come on, even when it's hot outside. I'm convinced outside temp has little to nothing to do with it, as I've ridden 1,000 miles (1,609 km) in various temps. I'm inclined to think I didn't replace enough of the wire OR the connector that plugs onto the sensor. It was cracked but I checked the fitting (looked OK) and placed Anti Corrosive Zinc Paste on the connector (BTW, I put the paste on ALL connections when I have them apart...have learned it saves me MUCH future troubles).
I'm rather OCD about everything running and looking right on the bike, but I'm not about to purchase a new ECM just to make the F1 light go away (I'd rather spend my money on other stupid farkles for my bike). I've read enough about this F1 issue to believe it's no issue at all, mechanically speaking. My only concern is, what if there's another NEW issue and the F1 light is still indicating 26 blips from the knock sensor and I don't see another F1 trouble indicator because of it? Will it blink another code as well, thus indicating TWO independent issues? I don't know...
I'm going to open her back up and replace more of the wire and attempt to replace the connector as well. Like I said, it seems as though that partially fixed the problem, but not every time I ride. I will post here again with whatever results I get.
Ride Safely!!