Pulsing high speed vibration, wheels, drivetrain, idk

Finally got some more work done and have some more insight.

Replaced the rear wheel and tire; resolved the 50-60mph road noise/vibration. Apparently this is the speed in which most balance and distortion of the wheel and tire hits peak resonance. Some reduction in the 85mph+ but still there.

Also replaced the front tire and saw some improvement as well. I assume it had wear caused by the rear tire out of round. Some improvement.

Finally I replaced the rear axle bearings, both the needle bearing and the double radial ball bearing. This netted a definite improvement. The old bearings did not show any noticable wear, damage, or play.

I still have some vibration, especially noticeable on deceleration from 90 down to 80. Also I noticed it more during a sweeping right turn. As the original rim had a 1-2mm bend in the right side I wonder if the front has a distortion as well. Also believe the rear suspension may be worn, waiting on a dmr full suspension.

One last thought, I believe the vibration to be a culmination of resonate vibrations. Rear hub as it seats into the swing arm has a small amount out freeplay when loose and can possibly be set in a way that puts the wheel or chain out of alignment by about 1mm. The bearings in the rear possibly through noise at high speed. And suspension wear as well as wear in the swing arm bearings/bushings all contributing to a pronounced pulsing vibration.

I'll probably replace the front wheel next tire change so I can send the original set to get straightened and powder coated. The suspension should ship in a few weeks and I'll replace the associated pivot bearings and bushings. With luck I'll have fixed all possible contributing factors.

I hope this helps someone else not spend the money I have and I'm open to any and all thoughts. Fyi the vibration seems to be more prominent depending on air temperature, still there even with the clutch pulled in, shifted in neutral, and engine off coasting down from 90mph.

 

My VFR has always had that popping off the chain when on the center stand in 1st gear idling.

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I noticed the chain popping while on the center stand doesn't necessarily cause the same when on the ground. Once the chain was cleaned greased, and adjusted correctly it resolved for me.

 

Not sure how one would know unless someone rode behind and looked down. I assume it's not a problem once underway but mine did that when it was brand new.

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Short story:

Check your steering head bearings.

Long story:

Went on a road trip through Europe summer 2018 (based in Norway),

6.gen with ca48000km, Pilot road 4 tires with aprox 5000km on them, bike loaded with panniers and tankbag.

A lot of high speed motorway driving on that trip and noticed early on the exact symptoms you are describing.

Pulsating vibration that startet around 100-110kmh and disapeared at around 150kmh. Frequency independent of engine rpm or road speed.

I also noticed that the bike was very hard to balance at low speed, in slow traffic, in and out of traffic lights etc.

Did some road side diagnostics to see if i could find any fault on the bike but everything seemed to be ok. Checked the steering head bearing by compresing the forks with the front brake held in to feel for play, and rotated from side to side while on the centre stand, but seemed ok.

Did some searching online but found nothing with similar symptoms.

Concluded that is was beccause of by ressonance caused by a combination of the luggage, slitly worn tires etc. even though i had done similar trips before with the same luggage witouth these symptoms.

When i got back from the trip my fork seals had started to leak, so while changing them i got a chance to inspect the head bearing more carefully. With the front wheel off ,and the controls removed i could feel a notch/rough spot around the 12 o clock position.

I disassembled the trees to check the bearing and they were completly dry, filled with dirt and surface rust.

I cleaned and inspected the balls and bearing races, they seemed to be in perfect condition once cleaned, so i greased them up, assembled them, and torqued the steering stem nut to spec.

First impression after this was that the bike was much easier to control at slow speed, they way it should be. And although i haven't ridden the bike with full luggage yet i have not noticed the vibration since then. Hoping to get a chance to do that this summer, but i am pretty confided that servicing the bearing will have helped.

I might have missed it, but could not see that you have looked into your steering head bearing yet, and based on my exerience i would suggest you do.

Fredrik

 

Thank you. I haven't pulled them but I had the forks off and moved the triples around. Also had a shop check but they just did the feel test. Low speed steering feels fine as far as I can tell.

I'm ordering the allballs kit to eliminate that possibility

 

Recently I've been doing alot of thruway, 200 miles a day, and I've had time to feel things out.

Noticed the vibration in the left grip/fork is much more noticeable.

Noticed scalloping development on the tire snipe but only the left side so far.

My DMR suspension is still on backorder unfortunately to eliminate the possibility its something there.

 

"Pulsing vibration" is caused by two things vibrating at close to the same frequency. As the two things vibrate at slightly different frequencies they periodically line up at the difference between the two. ie if you have an 80 hz and 84 hz vibration you will get a 4 hz beat frequency. The frequencies also have to have a common multiple ie 4 divides into both. This is why generally it only appears at a very narrow operating range. Both vibrations may be present all the time but not be noticable until the speed (frequency) of whatever is causing the two gets to that close relationship and then they add to each other every time the peaks line up (beat frequency) and it becomes noticable.

The vibration of each of the two components might be quite reasonable independently so it will be hard to find. That and the fact it only occurs at "higher" speed will make you search difficult.

I agree with everyone above that it sounds like it is not the engine since the vibration does not disappear with the clutch pulled in.

Wondering about the chain since it runs over two sprockets (different frequency) which will be different but related multiples. You don't say if the problem existed before, after or both with the new chain?

 

The problem has been persistent since I bought the bike. New chain and sproket made no difference. New tires lessened it for a few miles, barely noticed it. Seems linked to the tires, temperature, and how hard I ride. Strangely occasionally i wont feel it at all.

It usually starts around 80mph. Feel a pulse start in my left grip then it seems to move through the bike into the seat and tank. I dont feel it in the right grip strangely. It builds in intensity with speed and then goes away at 115ish. Frequency increases but not directly to speed. As you slow down the vibration continues to be felt below 75 but once it ceases it wont start again until 80.

Chain lube and tension has no effect. Gear selection doesn't effect it asside from engine vibration at higher rpm drowning it out a touch. Engine load and throttle position has no effect. Cutting the engine has no effect, clutch in or out has no effect.

New front tire started wearing aggressively again. Outside edge of the snipe, both sides, on the left however the transition isnt smooth and is cupped outside of the snipe specifically where the snipe is cut in closest to center line of the tire. The right side is a smooth transition.

I definitely think its harmonic in nature. I'm left with possible front wheel (have a new used one to try, head bearing but theres no play or sign of wear, suspension problem in the front, maybe an imbalance between the forks, clutch bearings or something in the output shaft but I doubt it. Lastly possibly chain alignment or alignment between front and back. Given chain tension doesn't have effect and I dont have binding or uneven wear I'm ruling that out. Wheel alignment I'd expect the steering dynamics to differ between left and right but the bike feels neutral.

I hope to find that the front wheel is ever so slightly tweaked and the fork cartridges are not in balance thus amplifying and dampening thus causing the issue. This in turn amplified by bike harmonics. Brake noise, rotor vibration. Idk. But I also feel like I'm missing something simple. Seems it always is.

 

The problem has been persistent since I bought the bike. New chain and sproket made no difference. New tires lessened it for a few miles, barely noticed it. Seems linked to the tires, temperature, and how hard I ride. Strangely occasionally i wont feel it at all.

It usually starts around 80mph. Feel a pulse start in my left grip then it seems to move through the bike into the seat and tank. I dont feel it in the right grip strangely. It builds in intensity with speed and then goes away at 115ish. Frequency increases but not directly to speed. As you slow down the vibration continues to be felt below 75 but once it ceases it wont start again until 80.

Chain lube and tension has no effect. Gear selection doesn't effect it asside from engine vibration at higher rpm drowning it out a touch. Engine load and throttle position has no effect. Cutting the engine has no effect, clutch in or out has no effect.

New front tire started wearing aggressively again. Outside edge of the snipe, both sides, on the left however the transition isnt smooth and is cupped outside of the snipe specifically where the snipe is cut in closest to center line of the tire. The right side is a smooth transition.

I definitely think its harmonic in nature. I'm left with possible front wheel (have a new used one to try, head bearing but theres no play or sign of wear, suspension problem in the front, maybe an imbalance between the forks, clutch bearings or something in the output shaft but I doubt it. Lastly possibly chain alignment or alignment between front and back. Given chain tension doesn't have effect and I dont have binding or uneven wear I'm ruling that out. Wheel alignment I'd expect the steering dynamics to differ between left and right but the bike feels neutral.

I hope to find that the front wheel is ever so slightly tweaked and the fork cartridges are not in balance thus amplifying and dampening thus causing the issue. This in turn amplified by bike harmonics. Brake noise, rotor vibration. Idk. But I also feel like I'm missing something simple. Seems it always is.

 

Reason I mentioned ABS and rotors not alighned, maybe something to look into.
My experience, I was having strange vibrations when at full lean. My bike has ABS, at which point I thought maybe it was TC or something kicking in.
I inspected my tires closer, and I have noticed a wavey wear pattern in the front. Bike had 3k miles when I got it, and about 4k when I noticed tire wear/vibration. I am at 9k miles now, and I finally(so smart :facepalm: ) replaced rear tire, and decided to adjust suspension to suit me, I noticed a discrepancy.
The issue:
My spring preload was set 1 notch softer on the left shock (3 notches), and the right shock is set to 4 notches! Before changing anything, I then decided to adjust my damper preload, and out of curiosity wanted to find out (soft and hard) the limit of the damper adjustment screws. Left shock 7.5 turns, right shock 2.25 turns. I am baffled, bought a used bike, decided to adjust the suspension a year after owning the bike and what the actual #$%@. Going to the dealer in AM to get some answers. If the 2 shocks are different, may be looking for an upgrade.

 

I've played with suspension alot but I'm actually waiting on a DMR setup. Backordered of course...

Interestingly I replaced my stock mufflers and the problem vibration has changed dramatically. Given I was still having vibration even when I cut the engine before I can only imagine weight has something to do with it. I didn't feel anything loose in the factory mufflers and between the 25lbs I must have shaved with the new ones plus the weight lost removing the hardware for the bags...

So I've been playing with suspension wondering if its possible I've been too soft on the rear or if theres actually something worn in the suspension joints. I guess its possible my nose was too light.

New rim and tire on the front and still a hint of something. I'm riding 1000miles a week commuting right now so I have alot of opportunity to test suspension and tire changes lol.

One thing I considered, I've always wondered if the rear axle was a culprit given a post I read where someone had the same issue and ended up replacing the rear hub carrier as the shaft was stuck. I'd thought bearings but that made no difference. Given my rear wheel bend I'm wondering if the shaft is ever so slightly tweaked. When I changed the exhaust I removed the rear wheel. I did notice the wheel is wearing slightly more in one area than the rest.
If I accidentally replaced the tire, say 180° from that spot the wear may have balanced out the tweak in the shaft. I'm waiting to see if the vibration comes back as the tire wears. Also getting a dial indicator to check the shaft and rotors.

 

I've got an appointment for a dyno tune in August, PCV came in! Going to have the starter valves professionally synced and also have help me setup my suspension. With luck it will make a difference.

Currently 85mph feels more like a wheel balance issue than a pulse. Unfortunately the engine gets vibey at 6k and the exhaust amplified that so it's tough to identify things. I hope to get that smoothed out. Wonder if rubber hangers for the muffler would help.

 

I had a vibration in the handlebars after installing new tires. Thought the Honda shop bent a rotor, so I checked the runout but it was good. Put on another new front tire, went from Dunlop to Metzeler and the vibration went away. I'd suggest you install another front tire using a different brand, quality control issues?

 

As you may remember I have a similar issue. I noticed this weekend while cleaning my chain, while holding a rag around the bottom of the chain and turning the wheel to clean it the chain would tighten up at one point in its travel then loosen back up. Only a very short section felt tight. If the sprockets are new what could cause this? The chain and both sprockets are fairly new. I can imagine that could cause the vibration I've been getting over 80 mph. Thoughts?

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On a used chain this is fairly common. I saw the same thing on a 2001 I bought in May.
The chain links wear unevenly and you can get sections that elongate more than others but the sprockets (especially rear) pull the distance of the first link on and last link off the sprocket to the "normal" pitch of the chain. This gathers the slack on the sprocket.

If you roll the wheel to the point where the chain is slackest try pulling on the chain at the back mid point of the rear sprocket. Youll find you won't be able to get the chain to come of the sprocket very far. This is because the chain has not worn much on that section.

Now roll the wheel so the chain goes tight(est). Try pulling the chain at the back of the rear sprocket again. I'll bet you find this section lifts alot more off the sprocket. This is because the chain is worn more than the average on this section and the sprocket pitch has gathered the slack of that section on the sprocket and therefore there is less slack in the span of chain between sprockets.

I was amazed at how much variation there was. I'm a bit surprised you are finding it on a "fairly new" chain and sprockets. Mine had 38K Km ( approx 25 K miles) on it and I am pretty sure it was the original chain.

When adjusting the chain I always check the chain while rotating the rear wheel and eyeballing the slack. As you found out its pretty evident when the variation gets bad enough.

 

This chain maybe has 2000 miles on it? Same wth sprockets. This problem was what caused me to replace them a couple summers ago. I wonder if something's off at the rear hub? Because I was happy to see the new chain and sprockets cured the problem at the time but sad to see now it's returned.

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Just had a set of Dunlop Q3+ put on a set of wheels I bought off a member and put them on a few days ago. Now the vibration is gone, even over 100 mph. In my case it must have been a poorly balanced front.

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Well I've had 4 sets of new tires in the past 3 months, over 12,000 miles, 2 sets of wheels, new suspension, ect. Adjusting the suspension to correct sag front and rear as well as ensuring the rebound and compression are balanced front and rear. Head bearings, cam tensioners, and another new chain.

However I'm happy to say I did find my culprit!

My chain (10k hard miles over 4 months) was making some god awful vibration and I've had a slightly warped rotor. In addition I've noticed what I would absolutely believe to be a bad wheel bearing in a car albeit inverted. Vibration going straight, smooth when I lean. Wrote it off to tires...

Well as it turns out I noticed the chain was moving side to side on the rear sprocket and the new rotor was still acting as it was not true.

The rear bearings got replaced early thus season and later I realized the rear axle was toasted. Replaced it and worlds better but now it seems that in the weeks between the old axle smoked the bearings. Anyway new bearings part 2 and should be good.

As a heads up, looking at the old axle theres tell tale wear and with the bike on the center stand and rear wheel spinning I was able to look through the axle and see one end oscillating compared to the other.

Now I've read alot about these bikes and rear bearings, let me tell you, I'm not amateur in terms of automotive mechanics and physically inspecting the rear assembled and disassembled I was not able to identify any tell tale signs of wear. No visable play, no catching or roughness in the bearings when spinning or rotating the wheel. The only proof is the axle oscillating. The new axle appears straight still so I believe the issue is the drive side dual bearings. They do feel perhaps a little tight but smooth none the less.

 

As conformation I will post some pictures next week of the chain/rotor movement and the old axle wear. I very much hope this helps in the future.


Also as an fyi. I posted previously that the pulses changed when I installed slip-ons. It seems, as someone previously pointed out that the pulsing is infact harmonic in nature. Some may notice that the engine even feels rough or uneven when your chain is dry or worn. Same is true with worn tires.

I've had a unique opportunity over the last few months to observe and try many different combinations due to the unusually high mileage I ride. Currently aprox 200-300 miles a day. Needless to say I've made many changes and adjustments to observe changes.