Engine rattle above 3500 rpm

I am hearing something that sounds very much like his description also. I hear it at around a steady 4K rpm while cruising.....but when I get on it hard and take it up to 7K I don't hear it. It doesn't sound alarming, but its strange and has me a little concerned.

To me it sounds like big (huge even) gears meshing at a slow speed. Kind of a notchy sound....if that makes any sense at all.

I almost have to tilt my head a certain way to hear it, and if there it a stiff crosswind I can't hear it. I heard it the very first decent ride after vacuum syncing the carbs for the first time, never heard it before. I remember exactly where I was when I heard it first, I know its not that I simply didn't notice it before. Funny.....but once I got the bike running really well, the noise appeared.

I'm not thinking the OP is going to chime in here as he hasn't visited in almost 4 yrs. I'm going to try what wiredgeorge suggested and give the brakes a little squeeze....but its going to be hard to tell because as the OP describes, the noise goes away as soon as I let off the throttle. Have to try to hold the throttle open and squeeze the brakes at the same time I guess.

To me the sound is coming from the front right side of the engine. I know I have #3 exhaust valve set too loose (.17) so maybe thats it?

I let a friend ride it and he said exhaust leak.

Another thing to check for is a drive chain in need of service or replacement.

Good Fortune!

Patton wrote: Another thing to check for is a drive chain in need of service or replacement.

Good Fortune!

That's right....the other thing I did just before the first ride when I heard the noise was to clean/adjust the chain. Forgot about that. It was the first time I had given it a really good cleaning. Sprayed WD-40 down thru the links while spinning the back wheel, then hit it with the air nozzle to blow all the crap out and off the chain. Went thru about 1/2 can doing that, going back and forth between WD-40 and air until it was clean. Then re lubed with Champion chain lube, making sure to get the lube inside the rollers like the service manual shows. The chain was filthy, full of grime and grit.

The sound does sound like the sound of the chain while spinning the rear tire by hand. But it sure sounds like its coming from the opposite side of the bike and from the front. But the way sounds bounce around at 60mph, no telling where it's really coming from. It could be that I hear better from my right ear too.

When my 76, 900 outer left rod bearing went out it only made noise above 3500rpm, a rattling, cracking sound. I f you have an exhaust leak the soot would be all over the exhaust port. you could try putting the bike on the center stand, in gear and wheel moving, listen to the noises with a 2 to three foot length of garden hose. It should be easy to find.

But did it make the noise only under load or either way?
on my ride to work this morning i left the helmet at home to listen to the bike and it definitely sounds like its coming from the front (near header) but i just installed new exhaust gaskets and i would think exhaust leak wouldn't care if there was a load on the motor or not. if i pull in the clutch but keep the rpm's the same the knock is gone. matter of fact i can hear the knock while riding the whole time above about 3300 rpm until i let off at all.
as soon as i let off the gas its gone.
im going to do some plug chops on the ride home but im starting to think this motor will be back on my bench soon
i will say the chain and sprockets are in desperate need of replacing as i made the mistake of tightening the chain while on the center stand a couple months ago causing me to learn how to replace the rear tire bearings.
lots of lessons with this bike. glad i picked it up for $400

You guys might be on the right track, but I'll share my experience from a couple years ago.
My bike suddenly developed a persistent rattle sound that would only show around 3500-4000 rpms.
Convinced the nerve-racking noise was coming from the motor, I tried to avoid that engine speed for a couple days, hoping it would go away...it didn't.
The noise (an exhaust vibration) only came-about at that specific rpm range. After banging around on the stock exhaust muffler and hearing tinking metallic noises, I figured out that things were loose inside, so I proceeded to select likely spots to waste a couple rivets.
Persistent pipe banging continued until I got to the front of the motor, where the #4 down-pipe made the audible tink. With no way to service it, the hunt ensued for a replacement exhaust system. Good-n-cheap stock replacements were unavailable, nor was a suitable header specifically designed for the application. Man, I was stuck.
What I wound up with is a V&H system designed for the KZ1000-J, with minor adaptation at the megaphone...the best thing (that wasn't supposed to work) I ever did.
We've been singing together ever since!

I cant tell you how much i hope this is the problem with my kz.
Is there any easy test tor exhaust problems other than co2?
when i ride and lean forward to listen it really sounds like right up in front but that could still be a number of things.
the plug chop tonight should tell me whats going on in the cylinder while the noise is going on.
i dont know how the motor can sound great on the stand and make that racket while under load.
thanks for the reply!

Dbuttsvfs wrote: I cant tell you how much i hope this is the problem with my kz.
Is there any easy test tor exhaust problems other than co2?
when i ride and lean forward to listen it really sounds like right up in front but that could still be a number of things.
the plug chop tonight should tell me whats going on in the cylinder while the noise is going on.
i dont know how the motor can sound great on the stand and make that racket while under load.
thanks for the reply!

On the 1100 Shaft, the factory exhaust down-pipes were double-walled...the problem was one loose inside pipe.
If your exhaust is stock, and tapping against each down-pipe (engine off) while listening for loose metal-to-metal noise does not reveal a problem, then its something else. Check to see that all clamps are tight.
Good luck.

Is the 82 kz 550 ltd double walled?
it sure didn't seem like it but ill have to tap around and see how it sounds.
the exhaust is stock i just have pods on it and it pulls hard through all rpms but that rattle is irritating and although its there when cold it definitely

gets louder once warm.
here is a picture of one side of plugs. they all look about the same.

I just gave my down pipes a knock with my knuckle. Sure enough the right side pipes (the side I hear the rattle from) make a buzzing sound when I hit them. The left side pipes sound solid, like thumping a ripe watermelon. I checked the nuts and they are all tight to the head.

My pipes are stock LTD pipes, I have read they were NOT double walled? But the pipes show no color so that would imply double walled right?

Hopefully this is all the problem is, If so I can live with it. But how can I be sure? Any ideas? I'm not going to start drilling holes and putting pop rivets in my factory exhaust.

Finally put up a video of my bike, as you can tell by watching it I need help

Wow....is that really how it sounds or did the video exaggerate it? If that's how it sounds then mine doesn't sound like that at all. Mine is a much more muffled sound.....almost like a cat purring.....deep sounding, not sharp like yours in the vid. I have to listen closely to hear it on mine.

I'll have to go ride my bike and listen very closely again. See if its more pronounced at cruise or on acceleration. I think I hear mine more at a steady cruise around 4k rpm, 5th gear @ 60mph. If I remember correctly anyways....I'll need to ride it again to be sure.

How did you capture that video?