Aaron, the symptoms sound *exactly* like the problem I had with my 1981 kz550 (standard model).
DiamondSkyBlue1000 already alluded to this above, just thought I'd tell you how the same problem on my kz550 got solved.
I notice that after you did the manual cam chain tensioner install, and maybe I read too much into it but you said "...just not use to the clattering valvetrain which is a totally separate post!"
so it sounded to me like you're still getting noise there.
My '81 kz550 made a heck of a mechanical racket at idle. But it sounded fine when running through the gears. Drove me crazy, I'm at a stop light, it's making so much noise, people next to me at stop lights had this look on their faces "ahh, poor guy, can only afford an old bike with a blown engine" the rattling was LOUD.
I thought 'cam chain' but it wasn't that.
My carbs were WAY out of sync. And it was in fact a chain that was making all that noise -- I knew it sound like a chain-sort of noise, embarrassing me at those stop lights.
It was the PRIMARY chain.
At idle, one of my carbs (#3) was open more than the others I later found out.
So at idle, when #3 cylinder fired, it fired with more power than the other pistons due to the extra gas flow (the #3 carb's throttle slide was open too far at zero throttle position).
So the crankshaft sped up a bit when #3 fired, then slowed down when the other cylinders fired, then sped up when #3 fired, etc.
And the primary chain being connected to the crank was also speeding up/slowing down/speeding up/slow down due to the #3 throttle slide being open too much at idle and the other carbs were flowing less gas since their throttle slides were not open as much at idle as #3 (aka 'out of sync' condition).
The chain noise coming from the engine was due to the primary chain going taut for #3 then going slack then going taut for #3 etc. like CLANG-CLANG-CLANG-CLANG-CLANG.
I pulled the carbs. #3 sync was WAY out. The other 3 carbs were less wrong but they were not matched -- each carb has a different amount of slide opening.
I set all 4 carb syncs to the same.
NO MORE PRIMARY CHAIN NOISE.
At stop lights I didn't have to keep it revving anymore to keep the people in their cars quiet.
'I think your engine's about to blow up' gott dang it. I put a stop to that.
Carb sync.
If you still have noise, do what DiamondSkyBlue1000 recommended -- check the carb sync.
The taut/loose/taut/loose primary chain action makes sense now, but at the time, I was amazed how much noise that primary chain could make just because the carbs were out of sync.
1978 kz1000 A2 with Kerker
1980 Z1 Classic with Kerker
