[Zed7]

Yep, it's definitely the reflector.
I found that shoving some dense foam through the back of the housing between the reflector and the housing WILL STOP the rattling but I'm unsure as to how hot it gets. But it'll definitely work. I'll experiment with the dense closed cell foam to see how it reacts to heat.
There is that Phillips head screw on the back of the bucket. It serves to firm up the reflector. Tightening it helps, not loosening it.
To clean out the housing I took it in the house and filled it with cold tap water and swished it around then dried it. It looks brand new now.

If the foam seems to susceptible to heat, the only other decent solution would be to drill and insert nylon screws.

 

[Obo]

If you replace the halogen bulb for an LED it will help with the heat. If you do, there are a lot of LED's that are garbage as they don't mimic the position of the elements in a halogen bulb, and as a result the beam pattern will be just plain wrong..

There's been quite a bit of research done in another forum I'm in by a member with significant background in this topic.
Almost all of us have gone with the F2 style LED bulb. I can provide specs and links if interested. I have not done the replacement in my ZR7S yet (only in my Honda ST1300) as I currently have an HID in it and it's not failed yet. When it does I'll do the F2 LED replacement in a heartbeat.

As for fixing the buzz, there's a thread here about someone drilling a small hole and putting in a self tapping screw/bolt plug that stopped the headlight rattle.

Found it: Fairing Buzz again...

Here's the excerpt: Post #3 from @Doug Hyde : "I drilled a hole in the center front of the bottom of the headlight housing (imagine a hole roughly centered between Gump's two locations) and "threaded" a rubber vacuum cap up thru the hole until the tip barely touches the bottom of the reflector. Not only did it eliminate the buzz 100%, it's been doing its job without falling out or even loosening up for about 12,000 miles so far. The size of the hole and cap aren't important (I don't even remember what sizes I used -- it was whatever sized cap I had lying around), just pick a cap size that is slightly larger diameter than the hole you drill. Buzz eliminated for about 15 cents and 5 minutes work. "

Post #16 from @DaddyFlip shows his plug solution. Fairing Buzz again...

 

[Zed7]

Obo, that was some interesting reading. I really like the rubber plug trick as well.
What was also helpful was the member who used upholstery foam such as the idea that I had. He said it only lasted a couple of years then he had to remove it. But my takeaway was that it didn't melt, which is good so I'll not be needing to go the LED route.

The foam I have is stiffer than upholstery foam so maybe between that and a rubber plug or even a well nut we can conquer this buzz.

With the headlight unit in hand and while shaking it.. it is definitely the sound I was hearing unless there is more (only they were masked by the reflector buzz).
There is two ways the reflector buzzes.
One is the bottom of the reflector hitting the bottom of the bucket.
The other is the front edges of the reflector have loosely vibrated off the front insides of the bucket.
So with the foam I have, I suspect it will stop the noise for a while (as it pushes both up AND forward at the same time) as the foam is very dense. Then what I'll do is lay out drilling points on the bottom of the housing in case I have to drill in the future. (I'm hoping my foam will be permanent but if not I'll know where to drill and what to use thanks to the brave souls that have done it before me).

 

[Zed7]

Here's my attempted fix. I'm using a closed cell foam 6mm thick. It was used for packing plate glass.
I cut a piece 8 inches long by 3 1/2 inches wide. Then I folded one end 2 inches over. So I wind up with 6 inches long by 3 1/2 wide with a double thick end.
I shove the thin end in first the finally the fat end as far as it will go.
It firmly holds the reflector up and forward. No amount of shaking it can make it rattle.
Hopefully it lasts and won't melt inside.

 

[Zed7]

Well alright, as shown in my post above, my fix worked out 100% (for now).
I totally enjoyed my short ride today. No more box-o-rocks. I even rode just out of my neighborhood to a parkway with some curves in it. I gotta say, the suspension with the new damper rod modifications felt fantastic. No wallowing or diving on the brakes.. success.
And another thing.. I can already tell, those Conti Motion that you recommended are a great bang for the buck. I didn't push it too hard seeing as they only have less than twenty miles on them but they feel very stable and turn in nice. I don't think they have the feel or grip of my Conti RA3 but at nearly half the price, the Motions are more than enough for this bike.
As soon as I get my insurance and registration I'll take it out for a 300 mile ride. I'm so glad I bought it.

 

[Obo]

Glad the headlight buzz is gone. It certainly can be annoying plus you get funny looks from bystanders like the bike is expected to fly apart when you stop.

As for the ContiMotions for the price they are a decent tire. Are they the best? Nope, but like the ZR7S they are good at everything but not great at any one thing.

I'm not the kind of person to buy the least expensive tire regardless of the performance or handling but if I find a reasonable priced tire performs OK for how and where I ride and gets decent mileage then there's no need for a more premium priced and performing tire. The Motions fit that criteria for me. Others will have differing opinions which is fine.

As for a 300 mile ride the longest I've done on the ZR is about 350 miles in one day when we went to Laconia NH for bike week a few years back. By the end my butt was sore on the stock seat, but so were my 2 buddies with custom seats on their bikes (FJR & ZX14.) I was a little shy on horsepower that trip compared to them but we still all arrived at the same places at the same time even if I lost them for a while in between.

 

[Zed7]

I just now received my my insurance and plate in the mail so I'm ready to go. Probably Sunday if the weather is nice. And maybe only 200 miles or so seeing as I don't want to get too far from home in case something goes wrong, which I doubt, but the bike is new to me after all.
And I want to give the new front suspension a try. I'll bet I'm the only kid on the block that can sport these cool stickers.