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Vibrations at higher load and RPM, specially with passanger


Redbike
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Please give me you ideas, I am fustrated since I don't know, if it is the normal behaviour of these bikes.

I have my loved 2006 model for six years and mainly facing with this issue from the begining. (for now 49k km)
Despite all the maintanance, From 4500RPM constant vibrations can be felt from the motor through the seat, foot pegs, handle bars and tank. This vibration-like a big electric shaver is getting even stronger from 6000RPM and more in the 4valve operation.
When riding alone till 140km/h even on the highway for some hours, the bike has only a normal V-engine vibration, and it runs rather easy with minimum throttle and 5.5l/100km fuel consumption. But when I am with a passanger or accalarate a bit more in 3th or 4th gears, this electric shaver vibration is over everything else.
Is it normal for the 6th gens?

Its frequency is rising like the motor RPM, and last time I made an on the road vibration measurement fixing two acceleration sensors on the subframe bellow the seats, where I could see the vibration is like the motor firing speed.
I would also mention, parallel to it, even with warm engine I can hear some noise from the motor in Neutral,
This noise is not very loud but it is like a roller when running dry. Also our old washing machine did it before the bearing was replaced.
When running at idle speed. With clutch in, the noise is completly off, with clutch out it comes back again. I is normal?

Can you hear this king of noise from your bike?
Or should it come from the transmission bearings, gears?
Or the clutch? But when the clutch is in, so its bearings are rolling, I cannot hear it.

Yesterday I checked a vfr1200f from a mate. That bike was rather used one but completly silent while idling in neutral. I could only hear the firing noise, but no more.

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Abnormal.  Check your chain & sprockets.  Check your tires for uneven wear, and pressure. 

 

The sound you mention, it could be the CCT failing (look up vids for sound to compare).  But if it slows when you pull the clutch, it is more likely just a noisy clutch which isn't unusual on these bikes particularly as yours is now 15+ years old.  Busylittleshop posted the fix for that, I think it was to replace the circular bearing that sits in the clutch plate and a surrounding piece... search should help you find it

 

I'm sure others will chime in... my 6g rides very smooth up to and over 100km/h, but I can't speak to 140km/h+.  My clutch makes noise at idle, but when I pull in the lever, the noise is silent - I live with it for now.  Replaced the front CCT a year ago which quieted the clacking on idle, no issues since.

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Normal maintenance investigations:

 

- compression test

- can timing check

- valve clearance check 

- flow-test injectors

- measure injector power lines and grounding signals with oscilloscope

- test ignition system  on all cylinders

 

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Just curious - do you feel the vibration when raising the rpms in neutral? 

If you have a remote temp gun you can check to see if all 4 headers are the same temp - mite help locate a misfire.

Don't overlook the final drive - look for kinks in the chain, proper adjustment,  condition of sprockets,  etc.  If my math is right, at highway speeds the rear wheel is rotating in the range of 1,000 rpm and the drive sprocket around 2,500 - problems there could present as a vibration that's proprtional to engine rpm.  Also double check engine mount bolts for proper torque. 

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Had this recently. Check your chain tension! A slight tight spot in the chain and insufficient slack will cause this exactly as you describe. Goes away at steady speed as the rear suspension settles. Hope that helps

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Even though an 90º V4 sports perfect primary and second balances they
still vibrate to some degree and the one thing to eliminate if you
feel more vibrations or hear an odd rattle is a loose exhaust system
because it will amplify any of those vibrations to an annoying
level... tap the pipes with the palm of your hand to test if any bolts
points or connections are loose... also check the foot pegs bolts and
anything bolted to the foot pegs...
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Some of you guys are way overthinking this in your replies. Redbike notes this has been an ongoing issue for him since buying his VFR.

 

My 2009 VFR800 (89K km) also has a buzzy motor, especially noticeable in the right handlebar and both footpegs. I came close to selling it during my first year but talked myself into believing it would smooth out as time passed. 

 

Fwiw, I've owned a two 3rd gen VFR750s (total 145K km) and also a pair of 5th gen VFR800 (total 116K km). All of them had smoother engines, especially the 750s. As Larry says, VFR engines are not the smoothest in existence but something about the 6th gen VTec VFRs makes them the roughest.

 

Then there's the twitchy throttle and the dubious value of the VTec system. Hmm, need to come up with an excuse for keeping mine these last 10 years 🤔

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19 hours ago, Lorne said:

Some of you guys are way overthinking this in your replies. Redbike notes this has been an ongoing issue for him since buying his VFR.

 

My 2009 VFR800 (89K km) also has a buzzy motor, especially noticeable in the right handlebar and both footpegs. I came close to selling it during my first year but talked myself into believing it would smooth out as time passed. 

Both what you and the OP say are abnormal for a 6th gen.  When I had Helibars I would get a little bit of buzz at specific RPM but never with stock bars, and never ever with stock pegs.  Unfortunately my bike has seen everything between neglect and a high state of tune between the times when I owned it and other people owned it too.  Very low vibration is a key characteristic; I've never noticed any in other 6th gens or 5th gens I've ridden.  

 

If @Redbike is seeing the vibration rise linearly with RPM and not center around a frequency input and die down past it, that's even more of an indicator that it's something really not right.  I would look at everything the other posters have mentioned, as well as other sources of imbalance like starter valve sync, fuel injectors, spark plugs, cush drive, etc.  Chain tension or bad sprockets would be the easiest source here, without being able to hear the noise ourselves, etc.

 

 

 

 

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On 9/14/2021 at 11:25 PM, rhoderage said:

The sound you mention, it could be the CCT failing (look up vids for sound to compare). 

I thought I might have a failing CCT.  I got a louder exhaust and the noise went away 🙃

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On 9/15/2021 at 3:55 PM, Redbike said:

When riding alone till 140km/h even on the highway for some hours, the bike has only a normal V-engine vibration, and it runs rather easy with minimum throttle and 5.5l/100km fuel consumption. But when I am with a passanger or accalarate a bit more in 3th or 4th gears, this electric shaver vibration is over everything else.
Is it normal for the 6th gens?

Would just like to say that with the three 6gen's I've owned, I've traveled 10's of thousands of kilometres two up and never experienced any changes in vibration. Correct chain tension is even more important with the added load of an extra person. Err on the side of slightly looser, NEVER over-tighten.

I remember riding with another VFR owner once that was complaining of a vibration issue. I noticed the chain was too tight, we pulled into the nearest fuel station and backed off the chain tension - no further issues.

Chain age, sprockets, and chain tension seem to be major cause of strange vibration issues, along with all the other good suggestions here.

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^^^  yes, alot of riders don't take the time to find the tightest spot along the chain and adjust for proper tension there.  if the loose spots then are too many or too loose, a new chain is in order.  best to adjust chains cold and lube when hot and after riding in the rain.

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Hi Guys, and thanks for your many comments and suggestions.

As I wrote, I bought this bike 7 years ago (38k km) in a pretty clean concition,
New Spark plugs, filters, oil and tyres also the steering bearings and the front fork sealings and maintanance were performed in the first week.
Then I changed the chain set (DID 530VX). That time I felt sometimes strange vtec operation.
Then I went to our local CFR specialist, who is more than a Honda technician.
He made new maintanance, injector cleaning, valve clearance+vtec system check since sometimes he also felt this higher freq. resonances when riding alone, too.

Then he changed the clutch basket to try.
Finally at least the strange vtec operation was away and single mode drive resonances all above 4500RPM decreased to a ridable level.

When not being dinamic, it was ok.

But picking up my friend for a shorter ride, he said it was not a confortable ride since vibro massage from the seat.
He likes the bike (it is a red VFR) so we just went out on it some times in the recent years.
I also used the pick up my daughter or my son for a 100km trip in touring mode. They had no complain.

But when changing a bit to sporty mode with a bit of acceleration, the engine changed to a shaker mode. I also felt it from all the consols and the seat.

I am mech. eng. in the field of NVH and looked the vibrations with my private stetoscope and finally with a new digital stetoscope, as well.
The problem was, the resonances are comming much more while driving.

I also checked the chain and clean it in 500kms.
Then I got a Head acustic system also with 2 acceleration sensors and decided to make a telemety check.
I fixed the sensors bellow the seat on the metal subframe and put the data logger in the tank bag.

First I checked the starting process vibrations, then idling or reving in the mainstand and then on the sidestand.

I started for a short test run alone.
I switched to 3 the 4 gears and made a test.

When downloaded and analysis the sensor results I found, my feeling has really phisical parameters behind.

The vibration (vertical) amplitude was first linear then from 4500RPM progressive parallel to the RPM.

From 6000RPM the mentioned vibrations came to the level to be over all the others motor resonances, wind noise and the traffic in the road.

I made a frequency filtering, and I found the high resonance were the double on the actual motor RPM. So it is like the firing process.
Opening my repair manual I made an Excel map to calculate the gearbox, engine, valve system, oil and coolant pump's speed and possible excitations.
I also collected the gear pairs rolling contacting frequencies to see the root of the 150-200Hz high amplitude resonances when driving up the 8000RPM.

I found only the engine firing.

 

I went the to a service specialist who performed a digital trottle housing vacum check and adjustment and we also verified the relative engine speed of each cylinder in their firing process.
The bike has pretty massive and rithmic sound on idle and mid. range RPM, what we can hear and his result showed the same, too.

He made some small 10 rpm adjustments, but kept it mainly just constant. He wellcomed the results, best VFR bike in the last years.

However I told him, on the way I could feel the same 80kW electric shaver bellow me when driving him.

Then he has some idea, some bad past repairs of the gearbox bearings or imballance???

No way to find them and repair with a feasible solution for this old but new looking bike....

 

Then I called the remaining 3 honda dealers in our contry. To close the topic I thought to drive to see them after each other.
The first checked the bike acustic and the connctions of the frame, and said it must be a good one. Shaking on the road must be complex and not worth to repair.

The second said would retighten the frame bolts, what I did with my troque wrench. No loose parts, 100% stock model.

 

I did also a test run with other VFR owner. His bike was vibrate but moderate and not like a shaver.

 

For now I have 49k km in the bike. Fuel consumption one signal for 50km = 5-5.5L/100km.

When driving on the highway to the dealers, I looked it was running pretty easy at 130km/h. Single mode, only wind noise, some exhaust and the running trees around me. I said this mad bike wants to make me crasy???
Then switchnig back to gear 3 or for, I made some acceleration in 5-7000RPM. The vibrations were there. In 4 valves mode it became constant.

But driving in 6th gear the bike dropped the RPM and in 2 valves mode had no problem (I drive with 100 oktane benzin)

 

Some in the Hungarian forum said to buy loud exhaust and enjoy the tones. The moderator said to look the cluch for wear and clearance.
I can not do it at home, and the technicial did it 5k earlier so I did not want to pay more.

A few rider said their bike is silent but not to many complained. But my engineer brain see different.

Finnaly I said: my loved bike from my childhood was RC36. I had it and now also this RC46. This one is like a new, what I could not afford.

However I should not drive it when only looking for those agly root causes. It is not a joy.

I did not want to tell to sell a V4 800, but now I did.

Also the last dealers offered to change to some inline 4 and touring bike. My friend comming on the GS1250 pushed to the direction of boxer, preferably touring enduro.

But I felt, I have to stay on the v4. I asked the last dealer to show their vfr12f what I checked, too.

Yes, it has engine but I could not find the shaver in that during the test run. I felt it was the best news what I have to conservate.

So I told him, I want the switch the bikes.

 

I hope I will write only cool things about this big brother!

 

Many greetings.

Peter

 

(I linked the vibration test results- I preformed during the test run on my seats)

 

 

 

240890804_248986830439783_7820856581435599358_n.jpg

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Very clever vibration testing Redbike. Sounds like all your issues were in the 4 valve zone.

Good luck with the 1200. I'm sure you'll enjoy the extra power and 4 valve operation all the time.

 

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Thanks for the wishes 🙂

Well, with passenger or sporty style with more open throttle these vibrations already started from 4500RPM(from 106sec on the printscreen).

 

This measurement I did without passenger.

Left picture (sensor bellow the driver seat) shows this dominant vibration with high amplitude-yellow color in this waterflow diagram till 111 sec when I closed the throttle when reaching 8000RPM.

On the rear seat this frequency was also dominant. + the 20-50Hz range showed the bending motion of the subrame far from the bolting point at the tank.

But both position the 200Hz frequency I highlighted like the main symptom, what I found should be from the motor firing operation at this RPM.

I did this investigation to help the dealer service center to find the root cause and solve it for my big-big happiness. But the service leader told me, has no idea they could offer me max. to retighten the subframe, if it helps...
 

I was a 50 years old child having this loved Vtec, what I also 3D CAD modelled for myself when first came to the market.
The 1200, however it won't be this nice Red, must perform without issues not to change it to some BMW boxer....

 

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