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)