KZ1000 Engine vibration

Ok I dont like asking questions if I can search and find the answer to something. I have searched and I am still stuck.

I have an 81 KZ1000 LTD. 5k miles
I have a vibration that is driving me crazy. It is rpm related between about 4-5k rpms. Happens in every gear so definitely not speed related. It is just kinda a buzz. It is enough to blur the mirrors.

Here is what I have done to try to fix it.
Pulled carbs and cleaned them.
New jets.
Synched them.
New spark plugs.
New plug wires
Wired george relay mod.
Battery fully charged.
Compression checked and all is good.
Checked timing and it is dead on.
Checked for air leaks between carbs and head.
Loosened and retorqued all motor mounts to factory spec.
Checked valve clearances.

So now I dont know what else to do.
Is this normal for the KZ1000? My kz750 was so smooth.
It is driving me crazy as it is definitely noticeable.
I had put pods on and rejetted it but I think I may go back to the airbox to see if I can remedy this issue.

I dont have an enormous amount of time to work on this but I might try tearing the carbs apart again. Maybe I missed some small passage or something.
Also maybe cam chain tensioner? I will look into this tomorrow.

88alltrac wrote:

I dont have an enormous amount of time to work on this but I might try tearing the carbs apart again. Maybe I missed some small passage or something.
Also maybe cam chain tensioner? I will look into this tomorrow.

Will it do the same thing in neutral? If you rev it to 4000rpm on the centre stand do you notice the vibration? Is it something you can hear or just feel? If you can notice on the centre stand then a mechanics stethoscope might help narrow down if its top end or bottom end.

You've been pretty thorough in tuning, but its worth it to look into your cam chain and the tensioner parts. my '78 kz1000 has a small slipper blade in the front of the block that can wear prematurely. There's a lot of rubber dampers in there that age and deteriorate, they may need some attention.

hope this helps...

if the cam chain was loose or something wouldnt i hear it at idle? it idles great and doesnt make any noise. I will check but i am pretty sure it does vibrate in nuetral. I will see if i can isolate it a little further.

Do these bikes just naturally buzz like that? It has such low miles I dont think anything should we worn out.

when did you first notice the vibration before or after the airbox removal. also take aclose look at the rubber mounts in the engine cases does it seem like there is an extra amount of movement in them remember they are 27 years old if it was in the engine it would be noticeable at all rev ranges. if you rev the motor past 5000 does it go away.it could be related to the rubber engine mounts for sure.

It has done it as long as I have owned the bike. Maybe the last 500 miles or so. And it did happen before I took the airbox off. I will check the condition of the rubber mounts. Does anyone know if you can buy new ones? I didnt find any on z1enterprise. I think it does go away after about 5.5k.

then if it was happening before you removed the air box i wouldn't worry about carbs or engine anymore id go after the mounts is it happening at certain speed in high gear say 60 miles an hour because if the mounts don't cure it i would change my gearing so that it happened under that speed which you would be cruisig at. and if jeff doesn't have them you should be able to get them from kawi as they are the same on all the cop bikes up till now as well.

well i took a glance at the mounts without actually removing them. the rubber inside doesnt look dried out and cracked or anything. What am I looking for? Them to be hard and not absorb vibrations or shrunk and loose so they allow to much movement. I will price them out and if they are cheap enough i will just replace them anyway.
They do look pretty good though. Any other ideas?
You dont think it is carb related? Could I have missed some little passage or something. Would that make it vibrate at WOT?

your not at wide open throttle are you your only at 4-5000 rpm so that is midrange is it an actual vibration or is it surging.

it is a vibration. it is kinda a buzzing feeling but you feel it through the whole bike. it isnt like a bracket loose kinda buzz. i can have the throttle all the way open or just partially open and it still does it. if it was carb related wouldnt it depend on throttle position too?

Those rubber mounts are $20 a piece so I want to make sure that is the problem before I fork out the dough. I am a poor college student so I cant just keep throwing money at this.

there is a good chance you could spend a lot of time trying to pin this down and never find it...could just be "one of those things" that will drive ya bananas....i ve tried 3 sets of mirrors and i cant see crap out of any of them at speed...

Do you know if the motor has ever been taken apart?