Rattle at low RPM, any ideas? Emissions package?

I have a 1981 KZ750 LTD, and I have begun to notice a bit of a rattle sounds like its in the top end of the motor when at low RPMS, and while I am stopped. It has really been bothering me because I don't remember it doing this before.
I also have a very pronounced buzz at 4100 rpm that is a bit irritating, any Ideas if there is anything I can do about these noises?

My understanding is that 80,and 81 models at least, have this emissions reduction kit called Kawi-clean air system or something which re-filters unused air/gas into the air box?
Could someone explain this better to me?
A guy at a shop near Bloomington said he had removed the emissions kit from his 80 ltd and it reduced noises and helped it run smoother, is this possible?

What the "clean" system does is send fresh air from the air box into the exhaust ports. This is suppossed to help burn hydrocarbons (gas not fully burnt). There is a vacuum valve that opens when engine is runing to do all this.

I have removed this in my '91 Zephyr 750, by plugging the air box, and connecting the two cam cover takes together by a hose. However, I don't think this has anything to do with the noises you describe. This system is extrictly for emissions and does not affect anything else, other than maybe some "sizzling" from the exhaust. Unless, of course, you have a vacuum leak. I have not noticed any differences, either in performance or different noises.

I would think, without knowing your bike history, what you describe would be more related to carbs, valve clearances, or cam chain tensioners.

I have never had any very serious problems, but i would acknowledge the carbs are about due for a rebuild.
If this is a valve clearance issue, what can I do to fix it? It seems like it would be pretty complicated.
Thanks,
Mike

At least on the Zephyr 750 I am suppossed to check valve clearances every 6K mi. Yes, you have to remove coils, and valve cover, but it is not too bad. To me, the most tedious is scraping the valve cover gasket. A factory manual describes what to do. This is just to check clearances.

If valves need adjustment, then it gest more elaborate because the camshafts have to come out. But again,it is not too bad if you use the zip tie trick. With the Zephyr, I have to remove the carbs also, which is tedious. But you might also need to clean your carbs, check floats levels and synchronize, which may have something to do with not running smoothly. If all thise have not been done on your bike in a long time. You possibly need to get into this checks.