Here's a decreasing-radius turn that's not so bad. This is the intersection of I-380 and US-101 in San Bruno, just south of San Francisco. The flyover from eastbound I-380 from the bottom left to northbound US-101 along the right is the turn in question. I've drawn lines at right angles across the road. You can see that they intersect in two big groups, one far away for a wide turn followed by a bunch closer together for a tighter-radius turn. What makes this one spooky for me is that there's always a northwesterly wind blowing so I have to lean in tighter.

I might not have the radius lines in exactly the right place, but I think they get the point across.

This one is the infamous Fish Hook in Santa Cruz, at the intersection of Highway 1 (coming from the right) and Highway 17. When you stay on 1 you encounter this nasty a decreasing-radius turn. If you don't know this intersection, when you come westbound on Highway 1, you naturally expect that to go straight ahead on Highway 1. However, you make this wide right turn that fairly suddenly becomes about three times as tight.

This turn is notorious for surprising motorcyclists, often fatally. There's a discussion on the Adventure Riders Forum.