Inline 4s, wheel balancing and TBS- cause & effect

[MajBach]

Thought I would start a new thread after reading another about excessive vibration.

Ive owned five inline 4s and the FJ is the only one that I consistently suffer from hand numbness (I thought inline 4s were supposed to be the engines that experienced the least vibration?). Now I am not complaining, after all I have a 2009 with 70,000 miles on it so clearly I enjoy the ride, but, I would like to minimize it if possible and understand a little more about vibrations.

About 6 weeks ago, I installed and balanced tires myself for the first time. A few weeks earlier, I also did a lot of maintenance like TBS, valves and general lubing of parts and had a Penske shock installed and the forks re-valved. My first ride with the bike post-overhaul I observed so much vibration in the bars I almost thought I wouldn't be able to continue the trip I had planned. I either got used to it or the vibration subsided and life was great again, but, I still experience numb hands every ride( despite grip-puppies and bar weights), but some rides far more than others. Last night on my ride home, I seemed to feel a lower frequency vibration more like a shimmy that got worse the faster I went. It wasn't an in-your-face feeling but enough that I noticed it and tried to find a pattern related to speed or rpms. It was the first time I had even wondered is there a wheel out of balance? On a car, this is more noticeable either a steering wheel vibration or noticeable in a mirror or empty seat. I've always wondered what an out of balance bike tire feels like and if it really matters. When I got home, I checked and confirmed none of the weights had been thrown. Ive got almost 6000 miles on those tires now (PR2s) with no noticeable wear or cupping.

Finally there is the TBS. I hate having to do this. The symptoms of out-of-balance are so annoying, the fix so satisfying but, so very short-lived, like 1000-2000 miles. And currently, my bike could use one.

So, I am wondering, which of these can contribute to hand numbness? An out-of-balance throttle body shouldn't have any impact at highway speeds, correct? And how do you really know if a tire needs balancing once on the bike? Can this cause high frequency vibration in the bike? How about suspension settings? And if so, which way, i.e. softer = less/more vibration?

(Edited for formatting)

 

[RossKean]

If engine-related, the frequency (and intensity) will change as a function of RPM so travelling the same speed in two different gears might help identify that as the primary source.

Suspension/tires/wheel bearings/driveshaft etc. will be a function of speed. I wouldn't be surprised if your 6000 mile PR2's were part of the story. I stopped using PR2 fronts because they got ugly after about half-life. I don't know whether some bikes are much worse than others or if some riders are more tolerant than others - perhaps a bit of both.

FWIW, I haven't done a TBS on my '07 for something like 80,000 miles. Probably should get that done sometime...

Good luck!

 

[C&C]

Vibrations in and of themselves may or may not produce numbness; numbness may be a product of throttle spring tension, lean from the sitting position and probably others things I/we don't know about. Numbness is a product of the nerve being either pinched or otherwise aggravated; vibration may actually increase blood-flow (but that's another story).

 

[Bill Lumberg]

TBS didn't change anything on mine, and I waited until after 20K to do it. I either don't have a lot of buzz or am fairly impervious to it. But I will say that grip buddies do far more to dampen felt vibration than stock grips or grip puppies do. Mine feels pretty good with stock or HVMP heavy bar ends, but was terrible, more like what you're describing, when I subbed in anodized aluminum bar ends. Those came off with a quickness. For a shimmy, I'd prejudge that tire balance or tire wear was the culprit, but I'd check and make sure everything was tight just to be safe.

 

[MajBach]

Vibrations in and of themselves may or may not produce numbness; numbness may be a product of throttle spring tension, lean from the sitting position and probably others things I/we don't know about. Numbness is a product of the nerve being either pinched or otherwise aggravated; vibration may actually increase blood-flow (but that's another story).

I've considered these. The numbness is in both hands equally but not necessarily simultaneously (because I am constantly taking one hand off at a time to get blood flow or whatever). I've also experimented with riser heights and positions and adding or removing how much weight I put on my arms. The numbness can live long after getting off the bike, like right now...,my left hand still tingling and I've been done my 50 minute ride into work for over an hour. I do not experience these symptoms from any other activity, including driving my boat or flying to raking leaves or using a mouse.

 

[MajBach]

TBS didn't change anything on mine, and I waited until after 20K to do it. I either don't have a lot of buzz or am fairly impervious to it. But I will say that grip buddies do far more to dampen felt vibration than stock grips or grip puppies do. Mine feels pretty good with stock or HVMP heavy bar ends, but was terrible, more like what you're describing, when I subbed in anodized aluminum bar ends. Those came off with a quickness. For a shimmy, I'd prejudge that tire balance or tire wear was the culprit, but I'd check and make sure everything was tight just to be safe.

Ya know, you're right. This shimmy did not slowly develop but was sudden as I have driven the bike every day this week. Only difference was a bit of a head wind and higher speeds on the way home last night. I was planning on balancing both tires before next road trip but perhaps I should check bolts too before I get back on it. I recall when Two-Wheel Obsession guy was doing some front end stuff on his brand new FJer, the axle bolt was finger tight!

I've never driven without my grip puppies so I dodnt even know what stock feels like. Will probably look into some type of air or gel filled kind. My Dad had a pair on his '76 KZ 900 and I recall thinking they felt cool to touch.

I would expect that risers might contribute to vibration simply by increase the distance from the source.

 

[lele]

..for example my FJR seat vibrate a lot more @5000 rpm when my rear shock is in hard position.I think any bike or mechanism vibrate, u cannot control it 100%

 

[infrared]

MajBach,

Just curious, but did you do the factory-version TBS, or the Completely Un-Authorized TBS, posted on this web site? I'd expect to get better road-results with the Un-Authorized version, but I have not done the job on mine yet. I do use the larger HPMV bar end weights, and foam grips. Only rarely do I get numbness in a hand, and that is usually as much caused by a bad body position as from any vibration of the machine.

Cheers,

Infrared

 

[MajBach]

MajBach,
Just curious, but did you do the factory-version TBS, or the Completely Un-Authorized TBS, posted on this web site? I'd expect to get better road-results with the Un-Authorized version, but I have not done the job on mine yet. I do use the larger HPMV bar end weights, and foam grips. Only rarely do I get numbness in a hand, and that is usually as much caused by a bad body position as from any vibration of the machine.

Cheers,

Infrared

I did do the unauthorized TBS last year when I did it for the first time and regretted it. Not because it was bad advice but more because I didn't know what I was doing enough to deal with any curve balls. The bike did show a marked improvement at idle speeds and no difference at speed. The part that was really confusing for me was how one throttle screw adjusts two at a time. I could never really get things to align and once I got close at 4000 rpm, the idle sync would be lost. Plus there was that warning about not meddling with the bypass screw on the third factory set body. I guess it's always been a nagging thing that I screwed stuff up and couldn't return back to the start. Having said that, objectively, I have not had any symptoms of something being wrong aside from a nagging doubt in my abilities. I've been hoping for a PNW fall tech day to watch someone do this sync properly. All my TBSs now are just the shop manual procedure and the only thing I really notice is that when cruising along slowly at near-zero throttle, there is no surging or lurching. When this begins to occur, I feel it's time for a sync. I don't put locktight on the screws either. Does anyone else?I dont dare back the screw all the way out for fear of losing it so I cant apply locktite to the threads anyway, just the head of the screw, which I did - once - and it just makes for a mess the next time you need adjustments.

 

[Mihalis fjr]

The TBS has effect only at idle and at about 1500 +/- rpms..Above this range has no any effect..

Believe me...

To confirm from where the vibrations comes,when you feel the vibrations pull the clutch lever and close the throttle.

If the vibrations comes from the tires will stay there,if the vibrations comes from the engine will disappear.

I had bad vibrations and i thought that they coming from the engine.Pulled the clutch lever at speed and the vibrations was still there.

The cause was the front crappy bt 021..Replaced by a bt 023GT and the bike runs smooth as silk..

 

[timk]

Maybe carpal tunnel?

 

[HotRodZilla]

No reason your bike should require a TBS every two to three thousand miles. Something is wrong.

 

[FJRay]

No reason your bike should require a TBS every two to three thousand miles. Something is wrong.

Gotta agree with AJ I've done a number of them and it's pretty much a one and done deal. I checked my 03 a few times in over a 100k and it wasn't off far enough to worry about.

 

[MajBach]

No reason your bike should require a TBS every two to three thousand miles. Something is wrong.

Any ideas?

Just to recap...when I am slowing down and have throttle nearly closed off, I often feel a surging or lurching. It's more prevalent the lower the gear since the engine has more leverage. It's almost like the bike cannot decide whether to accelerate or decelerate. I presume that this is occurring because one or more cylinders is producing more power than the others and this is because it is getting slightly more or less fuel. When I do a TBS, they are not typically out very much and I am surprised it was enough to produce the symptoms, but, once I adjust them, the problem goes away. I have also noticed - consistently - that when the surging starts to appear and I am ready to do a TBS, the idle rpm is about 200 higher than when I set it at the last TBS.

On a little more thought, I am probably getting more than 2000 miles. The last TBS I did was before I changed the tires and I have already got 6000 miles on them.

 

[MajBach]

The TBS has effect only at idle and at about 1500 +/- rpms..Above this range has no any effect..

Believe me...

To confirm from where the vibrations comes,when you feel the vibrations pull the clutch lever and close the throttle.

If the vibrations comes from the tires will stay there,if the vibrations comes from the engine will disappear.

I had bad vibrations and i thought that they coming from the engine.Pulled the clutch lever at speed and they disappeared.

The cause was the front crappy bt 021..Replaced by a bt 023GT and the bike runs smooth as silk..

This is such an obvious test that it concerns me I didn't think of it already.

So last night coming home I cruised in 3rd between 5-6000 rpm. It felt like I had bee hives in my gloves. I read your post afterwards and pulled the clutch in while driving at highway speeds on the way in today. Wow. The difference was so surprising I was actually saddened at how much vibration was there and how I became accustomed to it. Driving down the highway at 80 mpg with the engine at idle, the bike was so silky smooth I didn't even recognize it.

So, clearly this is engine vibration. Next question is: is it normal or excessive?

One thing I didnt understand about your post was you stated you pulled the clutch in and the vibration disappeared which led you to conclude it was the front tire. This make no sense to me. I did the same thing and it makes me believe it can't be the tire.

 

[Donal]

From the test you carried out it looks like it is engine related.

I would start with checking the engine mounting bolts, making sure they are all torqued up properly.

 

[Mihalis fjr]

The TBS has effect only at idle and at about 1500 +/- rpms..Above this range has no any effect..

Believe me...

To confirm from where the vibrations comes,when you feel the vibrations pull the clutch lever and close the throttle.

If the vibrations comes from the tires will stay there,if the vibrations comes from the engine will disappear.

I had bad vibrations and i thought that they coming from the engine.Pulled the clutch lever at speed and they disappeared.

The cause was the front crappy bt 021..Replaced by a bt 023GT and the bike runs smooth as silk..

This is such an obvious test that it concerns me I didn't think of it already.

So last night coming home I cruised in 3rd between 5-6000 rpm. It felt like I had bee hives in my gloves. I read your post afterwards and pulled the clutch in while driving at highway speeds on the way in today. Wow. The difference was so surprising I was actually saddened at how much vibration was there and how I became accustomed to it. Driving down the highway at 80 mpg with the engine at idle, the bike was so silky smooth I didn't even recognize it.

So, clearly this is engine vibration. Next question is: is it normal or excessive?

One thing I didnt understand about your post was you stated you pulled the clutch in and the vibration disappeared which led you to conclude it was the front tire. This make no sense to me. I did the same thing and it makes me believe it can't be the tire.

Well,as Donal said from your test looks that the vibrations comes from the engine and not from the tires.As you know all the fjr have vibrations especially at about 4000 rpms and above.Typicaly low frequency four cylinder vibrations.I feel those vibrations in my bike,also i rode many times the two fjrs of my friends.I feel the same vibrations.The vibrations above the 1500 rpms +/- has nothing to do with the TBS.As about my bike,i did the same thing,pulled the clutch at about 70-80 mpg with the engine at idle and the vibrations was still there.So with this way i understood that the vibrations coming from the tire.In my post i wrote it wrong!I wrote the opposite!I wrote ''Pulled the clutch lever at speed and they disappeared''NO,when i pulled the clutch the vibrations was still there!Sorry for the confusion!Also i wrote ''Replaced by a bt 023GT and the bike runs smooth as silk'' Yes,runs smooth as silk when i pull the clutch at speed 70-80 mpg with the engine at idle.When i ride normal i feel many vibrations,but they comes from the engine..I think that the best way is,try to ride another fjr to compare with yours if the vibrations are about the same..

 

[odot]

I think swapping rides with someone is a good idea......especially if they drive a Kia. Problems should go away.

 

[gumba]

Had some really smooth motor scooters. Could find vibration on all of them if I fixated on it. Put the death grip on those bars and you will feel vibrations. Relax and forget about it and the vibration will go away. Do your casual maintenance and forget about it. Find the sweet spot. Vibration fixation will send you to the funny farm.