Pulsing high speed vibration, wheels, drivetrain, idk

I've got an elusive vibration at speeds above 85mph. (Not condoning speeding) it's a pulsing vibration that seems to start in the bars and then move to the chassis then disappear and restart. Feeling like driving over a washboard with gaps between each. Problem presents even with engine off and clutch pulled. I do notice a faint vibration on deceleration at low speeds and oddly I have some feedback going straight at medium speed but it goes away with any lean. Not sure if its related, its very hard to detect and frankly could be the road.

Tires are new, problem existed prior to them. New chain, new front bearings, no play in rear end or swingarm, everything turns smoothly, sprockets are great. There is freeplay in the drive sprocket but it seems in and out on the shaft only and I guess that's normal.

I do have a little knocking sound at cold idle that I've attributed to clutch basket.

6th gen, 26k on the clock

Any thoughts?

 

Hmm - sorry no instant solutions but a few thoughts..

If you are saying that when you are doing 80mph+ you start to feel a pulsing vibration through the bars and that this does not stop even after pulling the clutch then the most likely thing still creating vibration on the motorbike will be whatever is still moving so primarily the wheel/tyres/drive chain. I think you can eliminate any engine issue as whilst it will be rotating presumably any fault there would also be witnessed by similar vibration appearing at similar RPM in lower gears.

My first thought appears to be like yours - this is probably an issue with the tires - perhaps they are damaged or not properly balanced. Even if they are brand new tires - sometimes glued on balance weights can come adrift and if only a small weight has come loose it may only be noticeable when the wheel is rotating at higher speeds.

Steering head/bearing play is another possibility especially as you say that you first notice this vibration through the bars.

Finally I wonder if that monster top box thing is somehow affecting the aerodynamics - perhaps remove it and see if the problem is solved.

As for shutting down the engine whilst travelling at 80mph, I would definitely not recommend it, so perhaps I misread your post.

Hope you get this solved - and please let us know how you get on.



SkiMad

 

6th gen, 26k on the clock

Any thoughts?[/QUOTE]

Rotors/Pads? When installing the wheels back on, after having new tires put on, and properly ballanced. Warped/Not aligned rotors/pads can cause vibration. Have you done work yourself, or shop?
Vibration on and off at speed suggests it heats up, and then cools off, the rotor and pads frictcion? When you turn vibration goes away, do you have non abs model? Just a few thoughts.

 

I have a similar issue which I posted about last year. It still exists and my situation is almost exactly like yours- vibration above appx 80 mph which is rhythmic. I also replaced both sprockets, chain, tires. I'm bumfuzzled.

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Tires I feel can be eliminated given the old tires had the same vibration at same speed. Chain is new but I'm going to change sprockets as it's inexpensive. I read many posts and it seems nobody ever bothered to post after resolution.

The most promising theories seem to be reguading harmonics and given I have engine vibration at 6500-10000 rpm it's a thought.

I dont have any experience with bikes besides this one so I'm flying blind. I noticed there's a damper in the rear hub and I'm thinking that while the rear wheel has no play and spins smoothly I'd not really be able to notice degradation there.

Its driving me crazy and I want to literally replace all the bushings and bearings just to make it stop. But I'm going to try to be systematic.

 

The bike is abs and I did notice the brakes very lightly dragging when I spin the wheel. I've not touched the brakes other than to remove the front wheel but the problem has been constant. That said the rotors all seem true but it's worth checking.

I'm really worried the problem will end up being an output shaft bearing if for no other reason than its buried in the case and I cant get at it.

I'll keep updating as I bleed money. I've got front fork bushings on order and will check the head bearings when I have the forks off. After that will be sprockets and rear hub damper, then rear hub bearings, swing arm bearings, clutch bearings and clutch basket will be last. If that doesn't resolve then I'll crack the case at the end of the season and look in the gearbox.

I noticed theres no weight on the front tire at all and I asked the shop and was told it didnt need any. Kinda surprised so it's going to get balanced again. The rear tire the shop had issues with because its single sided but balanced with and old machine, old tire had beads. Resting my heal on the swing arm I dont feel the vibration. That said, if it's in the hub the pulse could follow the chain so I'm not ruling anything out yet.

 

One last thing, again, not condoning or excusing my choices but I did take the bike out to 140 on an empty freeway, had a leader run ahead, no traffic. The vibration never changes frequency from inception at 85ish on and clears up at 125 smooth sailing to 141. But given the engine vibration smooths out at 10k if it is harmonic then that could be the reason. I did notice today theres a hint of vibration at 45ish. 70 is smooth as butter. Lower speeds I've either got engine vibration or rpms are low and it's just not smooth anyway.

 

don't know if i would rule out tires/rims. maybe a rim has a spot that can't be balanced easily, they don't really spin mc wheels as far a i have seen. my friend had a front end vibration so we through in an ounce of balancing beads and gone. they compensate for rim and tire discrepancies

 

Here's something (wheel related) that's easy to get wrong but also easy to correct:

Every back yard/suburban-garage motorcycle "mechanic" is absolutely sure that he knows how to re-install a front wheel. They're so sure of themselves that they never read the Honda Maintenance Manual chapter that describes step-by-step how Honda wants it done.

In the 5th Gen Maintenance Manual description of re-installing the front wheel it's a 10 step process. And one of those steps is absolute black magic: After having you install and torque the axle and torque the right-side fork leg pinch bolts and install the fender the directions tell you to pause and get on the bike and "work" the front suspension and exercise the front brakes... then you are directed to tighten the left-side fork leg pinch bolts.

Believe me, doing this correctly makes a difference in how the front tire works.

 

That definitely makes sense, and disproportionate load to the forks would absolutely cause change in the front dynamics. Almost want to intentionally induce a worst case from this and see how much its felt.

 

Unfortunately with the Q3+ tires the inside is almost "tacky" according to the shop that mounted them. By thier account beads would be worse than not. Given I have no front weight anyway I had actually thought about that.

I noticed the question about vibration going away turning above and asking about it being non abs, why would abs matter? Also to clarify, two different vibrations, or possibly same cause but the high speed is unaffected while the low speed, more a growling feeling, is affected by turning.

Now having dont some research I wonder if they static or speed balanced the tires. Speed balanced tires obviously would yield better results but given the shop seemed more geared toward cruising type bikes I have to wonder.

Dhinson66, I'd really like to compare notes with you. Perhaps, if this is as related as it seems, we might be able to resolve this together.

 

I'm as flummoxed as you. Unless it is where the Honda shop (mine) didn't torque the front wheel bolts properly (as GreginDenver proposed)? I've noticed the last 3-4 rides this year it appears to be getting worse-on the GoPro playback the image is now getting quite blurred when speeds creep up over 100 mph (don't promote speeding-was trying to get away from a pterodactyl).

 

It's always worth re-checking the wheel balance at both ends with this kind of thing.
If tires aren't new, they can cause issues if half worn. Check that tires are not cupping/scalloping even a bit (what tire pressure you running?)
Eliminate brake rotors issues by getting a tool and rotating the rivets/clean them out with a solvent.
Steering head bearings need to be checked while the forks still installed. At 26k they should be OK, but with the front wheel off the ground, if you have "self centering" steering, you need new steering head bearings. If not, check they are properly torqued and steering should have a slight drag side to side, but not loose.

 

Just had the wheels rebalanced and picked up today. No change.

Tire pressure is stock I've tried going up a few psi in the front and few up and down in the rear to no avail. Tires have less than 800miles. Even wear. Some wear on the outside of the snipes and high on the inside but normal not excessive and wear is uniform. Running q3+

And the issue was present before and after new tires at the exact speed and intensity.

Steering head is good as per the shop and my own feel but I'll be greasing and torquing this weekend. Most of the parts I ordered are in. Front fork seals, bushings (both sets), rear hub dampener, swing arm bearings, rear hub and axle bearings, and all the seals.

Also new sprockets, chain is new about 150miles ago.

Plan is to do sprockets, test, forks, test, ect. Unless I get impatient and go all out. In any event it will still narrow things down for everyone else.

 

Please clarify "at both ends" in regards to wheel balance. Mine have been speed balanced. If all else fails I may resort to trying beads in the front but I had them in the rear when I got the bike and they didnt do well at the speeds in question. Definitely lost balance at about 100mph and could feel the tire starting to "hop"

One last thing, I've got access to a snapon car tire balancer. I was considering pulling the wheel bearings and seeing if it would fit over the shaft on that. Wonder if it would yield better results

There is som vibration on deceleration at low speed, 10mph and below. I don't k ow that its related and the feel is quite different. Very faint. Does not seem to matter if I'm on the brakes tho. Either way theres no drag free spinning the front wheel and with light pressure on the brakes no noticable catching and high spots.

 

Update:

New sprockets installed today, front and rear had minor wear and the front had some play on the splines.

Rebuilt the crush drive, new rubber nubs, new bearing. Old rubber was intact but noticeably hardened. Bearing seemed fine but replaced anyway.

Results:
Vibration still present. In general the bike is smoother but the very low speed vibration and high speed pulsing vibration are still present. Subjectively I'd like to say its very slightly improved but Idk if I'm able to say that.

 

Another update:
Rebuilt the forks, new bushings and seals. Old bushings had the copper worn mostly off, the oil was absolutely gross! Sludge and crap in the lower shock tube. Used kerosene to clean it all out and then dried everything before re assembling.

Results: no improvement on the vibration. The bike feels much more stable and I'm way more comfortable riding through the vibrations now tho.

I rode 30 miles or so today prior to evaluate lastnights work better. The bike is overall a much smoother bike and definitely all and all a 100x better ride.

Next up is the rear hub bearings and swing arm bearings. Waiting on a part yet.

 

I think it's odd this problem has only been noticed on 5th generation VFR's. It sounds like you have replaced most of the theoretically probable suspect parts.

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Mines 6th gen.

Well I may have accidentally discovered the issue...

For kicks i tossed it on the center stand and threw it in gear. Right away theres vibration like an out of balance wheel. Mind you, twice balanced new tire, inspected by the shop 2x at cost to me.

Its getting dark but from the looks the rim is round at the edges but the center is not. Looking through the wheel with ut spinning you can see it moving up and down. Looking at the tire itself not so much.

So unless the wheel centerline is cast intentionally that way...

Alternatively the shaft could be bent but I'm not sure how to check.

Next I noticed theres a catching/popping in the chain. The sprocket is riding straight theres no noticable catching while free spinning the wheel and the chain and sprockets are all new.

 

So I'm 90% it's just the wheel. Can reference to a thread I started on the subject but it's a very very minor 1-2mm bend. Not seen with the naked eye.

Sproket and chain are good. Was very cold last night and the chain is a touch loose lending to the perceived issue.

Not 100% on the shaft still but going with a wheel and rechecking.