Need Help Violent vibration 5K+RPM

[labanina]

Hi,

I have 2011 Yamaha FZ6R (XJ6 Diversion), own it for 4 years, bought used from 1st owner, 56K km ODO.
Roughly Spring 2025, violent vibrations appeared on running bike, after ~4.5KRPM.
This happens even on stationary bike, on neutral.
Felt at handlebars, footpegs & seat, much stronger on the right side of bike.
Front brake master cylinder (mounted on handlebar) dies every year, if I put my hand on it while riding - it is getting absolutely hammered by vibrations.
All body parts in contact with the bike get numb after 30 minutes of riding.
I live in a small country and mechanics here are dismissing this complaint as minor and won't investigate.
Bike used to be smooth as butter for first few years, now it's just not fun to ride.
There are no errors in diag menu (except from me disconnecting airbox for access) and bike doesn't have any diag ports or anything like that.
I've tried a lot of things and are a bit at loss what else to do, would appreciate any advice, ideas or experience!

What I already tried:

1. Loosened, inspected and tightened all engine mounts to spec.
   I don't know if it was supposed to be like this, but upper engine mounts (ones that go onto brackets) were 8MM bolts inside 10MM frame holes.
   And a bunch of white powder came out after I loosened them for the first time.
   If there was supposed to be some sort of sleeve or washer there - it was gone.
   Inspecting threading inside engine block itself - it looked fine in definition and length.
   I've cut 8-10 aluminum pipe to tiny sleeve size and removed that gap between frame holes & bolts entirely.
   
   
2. Opened cam window on the right and inspected cam chain.
   Intake (left) side is tight, exhaust (right) side allows ~3-4mm screwdriver to go under it.
   I suppose that small right side slack is removed when engine is running.
   
   
3. Inspected Cam Chain Tensioner.
   Bike has the old version without any bolt outside.
   I think it's alright, but I ordered manual one.
   When tensioner is installed "fully erect" (incorrectly), it clams chain so hard that there is zero slack from either side and it starts eating into plastic guides on rotations.
   When tensioner is installed correctly (thanks, Brazilian videos), the cam chain situation as described above: 3-4mm slack on exhaust side.
   From this, I surmise that tensioner still works as intended and is still not on it's "last tooth" when installed properly.
   
   
4. Had a shop do Valve lash adjustment & sync for me.
   They also noted ~3-4mm movement of cam chain between camshaft sprockets.
   They told me chain is fine for now, but needs replacement next year.
   
   
5. Throttle body Sync: got all 4 cyl within 1 Cmhg at roughly 21-22 Cmhg, at idle ~1300RPM and a bit less accurately 4K RPM.
   This was recommended by other owners as solution to vibrations.
   I did it before and after valve job.
   
   
6. Taken out ignition coils, measured them (on-spec), re-cut HT leads, wrapped them in bit of isotape, crammed them into boots and fastened over with tiny worm gear clamps.
   This was also recommended by other owners as solution to vibrations.
   I notice no misfires but I saw some say vibration might appear even without evident misfire, caused by bad connection of HT leads to caps.
   
   
7. Replaced injectors & spark plugs.
   I initially cleaned injectors but one was still doing bad spray pattern, so I just replaced them all.
   The residue on old plugs was dark bronze with white isolator at the core behind contact still visible. They were in good shape.
   
   
8. Taken out and cleaned fuel pump filter, paid attention to rubber isolator while putting pump back together.
   I couldn't find new little filter for sale locally, delivery will take another month.
   
   
9. Tested for vacuul leaks.
   
   
10. Replaced air filter.
    
    
11. Measured compression, it was like 200 200 200 195 PSi
    
    
12. Tightened exhaust bolts: 8 at the headers going into engine, 2 rubber-bolt mounts for muffler (1 from each side)
    
    
13. Tightened footpeg brackets to frame.
    
    
14. Started using 10W-50 oil instead of 10W-40 previously, maybe at 8K+ RPM vibes got a bit better, or it might be placebo
    
    
15. A bunch of vibration-dampening solutions at the handlebars: heavy bar ends, filled bar with lead shot, put rubber pads between risers, installed thicker progrips etc.
    The effect is so miniscule it's not worth mentioning anything.
    I have original handlebar, thin dirt bike one and renthal road ultralow which I use right now with original risers-mounts.
    They all vibrate the same, badly.

Next possible steps:

• Yeah, cam chain might be replaced, but mechanic didn't tell me to do it immediately.
  Together with sprockets it's going to lighten my pockets for another ~500 Euros for parts, delivery and work.
  
  
• Yeah, coils measure to spec, but people report there are problems with them even when engine not misfiring.
  I would replace entire coil assembly, but what with?
  Just other pre-owned coils from the same bike?
  It's a wasted spark system so 1 coil per 2 cylinders, models from better Yamaha bikes won't fit.
  
  
• New manual cam chain tensioner
  I saw people install those a lot.
  
  
• New fuel filter
  I don't think fuel system is the reason, but it wouldn't hurt to replace it.
  

 

[Rayzerman]

I am not sure what the issue is and perhaps a little concerning is the camshaft chain being loose/stretched, possibly having an effect on valve timing. You're concerned about the cost.... you do not need new sprockets, replace the guides only if worn significantly, and CCT sounds OK.... but replace the chain.
As well, perhaps take the opportunity to re-check the valve lash, and re-shim as necessary to get all the clearances uniform across all cylinders, hopefully all at nominal. TB sync should be done after every valve lash change.

It seems you've done everything else you can. But these engines don't have balance shafts as far as I know, and in-line fours naturally have vibes in a certain range..... mine is between 5-6000 rpm and yes I get some tingling, but I don't think to the degree you describe. Mine has 20k km.

 

[labanina]

You're concerned about the cost....

I'm more concerned about it not helping. Also I just had a shop do valve lash adjustment for me. They said chain is okay for another year but I wonder if they just wanted money for work this year and the next too.

Here are cam chain videos, it doesn't look badly loose to me.

https://imgur.com/ZCboaZb

https://imgur.com/NOdr3zb

mine is between 5-6000 rpm

Yeah, every bike I owned had this small uncomfortable window. But this starts at 4K RPM and never stops.

I've also recently found that cyl1-4 exhaust headers are 40% cooler in all modes than cyl2-3. Investigating that for the moment.

 

[Rayzerman]

The vibrations you describe sound excessive....... as for the chain tension, once you've pried on it you've potentially loosened it by compressing the cam chain tensioner, your check isn't really technically correct.. Remember the chain is one continuous loop. To check the tension, the crankshaft should be rotated a bit clockwise. This would tighten up the front (exhaust) side so there is no slack. It would also rotate the exhaust cam to "pull" on the chain so there is no slack between the cam sprockets. This now allows the CCT to take up all the slack, so there is no slack on the intake side of things. Basically, chain is always under tension of the CCT when running, no slack anywhere else.

I'm going to ask some questions......

When the valve lash was checked, were the cams removed and any shims changed out?

If so, the procedure on reinstallation of the cams would be to verify all the timing marks lined up.... I have seen where one cam has been one tooth out, thus incorrect valve timing. This could cause vibration and other performance issues. Is it within your skill set to remove the valve cover, rotate the crankshaft to get #1 to TDC, set the timing mark at the crankshaft, then the timing marks on the cam sprockets should (must) be in correct timing.

 

[labanina]

Remember the chain is one continuous loop.

Thanks, yeah I figured I was judging it wrong. Makes sense: the slack between intake and exhaust side changes depending whether engine is pulling or not. Going to re-examine it. Manual CCT also might take more slack out of the chain.

When the valve lash was checked, were the cams removed and any shims changed out?

Not in any photos or videos they've sent me from the shop. I've only see them measuring with feelers. I will ask though how much honesty can be expected I don't know.

Is it within your skill set to remove the valve cover, rotate the crankshaft to get #1 to TDC, set the timing mark at the crankshaft, then the timing marks on the cam sprockets should (must) be in correct timing.

I think it is. Compared to what I have experience with, I'd need to take intake manifold off and then valve cover can be taken out. The gasket that goes around spark plug wells should be fresh too. I'll look into it on weekends, this sounds like 4 or 5 hours job.

 

[Rayzerman]

Well it's a simple question, did they have to re-shim anything or not...... your invoice would likely have included a charge for shims if they did..... what we're trying to determine here is if the cams were removed or not, and if so, were they put back in the proper timing.....

For you, if it's possible, when you remove the screws holding the valve cover on, you do not have to take it right off..... just lift the whole thing evenly so you can see the timing marks on the cam sprockets...... lined up with the cylinder head top edge, while the crankshaft timing mark is spot on per the manual. CCT is still installed. If you don't have a manual, here's a pic of the crankshaft timing marks...... Take a photo.

 

[labanina]

Well it's a simple question, did they have to re-shim anything or not......

They said they removed 1 shaft and changed some shims under it. Which seems to be the case.

crankshaft timing marks...... Take a photo.

All marks seem to align. There is a white sharpie mark around intake camshaft, so I assume this is the one that mechanics manipulated.

Cam chain is also fine, tensioner works properly. But it does look like it should be replaced next year.

https://imgur.com/jGzZ459

 

[labanina]

Some update on diagnose efforts since last post:

1. Replaced original CCT with manual one, tightened cam chain and ensured it doesn't eat into followers on running engine.
2. Got an oscilloscope and measured coil primaries & injectors: they look fine.
3. Re-cut & tightened coils again, measured resistance (on spec)
4. Tested ~10mm spark jump, all 4 jump this distance normally.
5. Got better engine mount bolts (M10 ones), dropped engine on jack, centered all mounting holes and mounted again.
6. Replaced fuel pump filter.

The problem of strong vibes past 5K RPM still remains.
I still suspect the coils/ECU on load so going to test warmed up coils and maybe look for local owners of same bike model to try test swapping them. Ordered cheap inductive probe for oscilloscope to measure coil secondary impulses, but those aren't reliable.
The cam chain I'll order end of month together with bunch of other miscellaneous stuff for the bike (bolts that unscrewed on the go and got lost, broken/lost plastic grommets etc.).
The TPS that maxes out at 90 looks suspicious too, I can adjust it when I take out throttle bodies for cam chain change.