Still the vibration issue

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Vasco Teixeira

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Hi all.

Been a long time reader of fjrforum, but this time decided to share in the forum these modifications I did on my Gen.II FJR since I never saw anywhere someone who has done something similar. Oh and sorry for the poor technical language!

Okay so still the vibration issue that affects a lot of FJRs... well first off I'll go through some theory that explains why I did these modifications. All inline 4 engines vibrate, its a fact and there's nothing we can do about it. The FJR seems to vibrate above average but I have noticed some time ago that the bike is actually very smooth. Stopped and at idle it barely vibrates, Yamaha has counter balancers on the engine that help a lot there, so I was wondering why the rider feels so much vibration .. Riding I noticed that, grabbing with the left hand the top triple clamp it barely vibrates, grab the handlebar halfway up and vibrates a little, at the grip it vibrates a lot. So theory is that the handlebar acts as one of those things to tune musical instruments (sorry don't know the english word for it!) and ironically the Yamaha logo has three of them. It amplifies vibrations, the farther you are from the origin, the higher the amplitude of vibration.

Touring bikes, having long handlebars are more prone to this issue. A sportbike with clip-ons has low vibrations because it has a very short path from the fork/triple clamp to the grip. In the FJR its even more apparent because the other bikes in it's class don't vibrate as much, mainly because the most common ones have no inline4 engines (STX and Boxer twins) the boxer twin vibrates a lot also, but its a lower frequency vibration that's different. The inline4 has a very high frequency vibration that causes hands to go numb. Another thing I noticed is that the Kawasaki ZX-14/ZZR1400 is a very smooth engine until you put that same engine in the GTR and suddenly you have GTR riders also complaining about vibration and particularly at 4000rpm same as the FJR... humm getting a picture here...

So I'd say the FJR has good (read low) engine vibration (mainly due to counter balancers) but poor vibration dampening in the controls, mainly handlebars. I owned a Suzuki RF900 and it had an interesting thing, the handlebars where cast as one unit and mounted on rubber dampers above the triple clamp, it worked good and I don't understand why Yamaha didn't do something similar.

So that's theory, first conclusion is the more the handlebars weight, the more they resist vibration amplification so first off was heavy weight handlebar ends, that's been discussed here, have them installed in my bike and that's it I'll move forward.

Next was the idea that bracing the handlebar somewhere wound act as a damper to lower vibrations. I had the idea of bracing both handlebars together, like dirt bikes that have a metal tube where the handlebar pad goes. After some thinking I came up with a simple brace attached to the handlebars by two existing screws that secure the wiring clamp.

Here's the brace, seen from the left, there's a small metal plate with two holes in it, the plate's lower right hole in the picture goes to a screw that's on the handlebar, it secures a wiring clamp.

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Viewed from top, the other hole of the metal plate is attached to a rod secured with two bolts.

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And almost finished work. Notice the metal plates have to be twisted so the rod aligns with them. And I also attached the parts together as to have some tension in it, as if the handlebars are now tensioned one against the other.

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And riding with this thing... well surprising good!! everywhere in the rev range vibrations where reduced, I'd say almost as much as having the heavy handlebars ends. Particularly at low revs its very smooth now.

Here's a few pics of the final work, now with better outdoor light but still crappy cellphone pics :D

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Plastic piece in the center of the rod is a GPS holder. I also added a black tube so it hides the rod and it looks a lot better. Putting the key in the ignition is a bit awkward now, but I can live with that.

So if anyone wants to try this go ahead! Its very cheap and makes no modifications to the bike, if you don't like it just remove it. Mounting takes a couple of hours tops, though take your time when bending the metal plates to align them, use two pliers and patience is a very good friend. You'll need a 21Cm M6 rod (you'll probably need to buy a bigger rod of standard length and cut to measure, I did), four M6 bolts and two metal plates, I used these (next pic) bought from a local hardware store (had to enlarge the holes to 6mm). I went all stainless and still was inexpensive. I also got a black rubber tube with 6mm inner diameter and that also was cheap.

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I have a ruler somewhere that has centimeter and inches, can't find it now so US guys will have to do the math ;) why M6 and not other size?? no idea... I went with what seemed best to me at the time...

Last, obviously I can't guarantee this will work with everyone.. your mileage may vary....

PART 2....

Okaaay that was last month... but being picky as I am, was not satisfied. My RF900 had rubber mounts on the triple clamp so I thought why not add rubber dampers to the FJR handlebars? They are removable so that should be an easy job.

Went to a local store that deals with those materials (o-rings, shaft seals, etc..) and not wanting to spend a couple of hours explaining the basics of inline4 vibrations to the guy at the counter, I asked for something to dampen vibrations between two metal parts. The guy gave me this at no cost

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Its a very dense rubber sheet about 1mm in thickness. Looks as if it should work...

I cut two pieces, drilled 4 holes in each for the two bolts and two shims. Here's how it looks mounted.

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Yes the pieces need to be trimmed to the handlebar shape, I'll do that. Now riding with this was good improvement, but not as good as the handlebar ends and brace. Yes again here there is a reduction in vibration, I'd say not as significant as the others but I just rode a few km with this, so still not sure. But in this case there is a trade-off, as the handlebars now are rubber mounted, you notice that it affects steering slightly, and I mean very slightly. The bike seems that bit easier to maintain in a straight line, but where is most noticeable is in counter steering, you notice just a bit of handlebar flex like my old RF900, which is not necessarily a bad thing! I really have to test this in my favorite backroad here in Lisbon that has a few 2nd and 3rd gear corners that test handling very well. But I say again, I noticed far bigger changes when I swapped the Metzeler Z6 front tyre to a BT-023.

I would suggest trying this but here BE WARNED that care should be taken when replacing the bolt and nut that attach the handlebar to the triple clamp. Because of the rubber damping, factory torque does not apply and I can't give a value on that, I torqued mine to what felt okay based on my experience but for some time I will keep the two small handlebar caps off to monitor the bolts and have a 17mm wrench and 5mm hex in the tool kit should a handlebar looses itself. I definitely NOT recommend this if you have doubts.

So final result is that the bike is very smooth up until 120kmh, vibrations increase after that but still very bareable at 140-150kmh. I went to see some friends a couple weeks ago, the return ride was 3 hours averaging 80-100kmh, with a 5 minute break, and had absolutely zero fatigue on the right hand! And I also notice the vibrations a lot more in the summer because of the gloves, in the winter it's much better with thicker gloves and I'm curious to see how will it feel when winter gets here. And right now I'm having the idea of patching the palm of my summer gloves with some material that helps, and piece by piece I'm getting there ;)

Vasco

 
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Interesting approach to a problem I recognize as well. Thanks for the info!

Since you cannot torque the handlebar fasteners adequately I would apply some high strength thread locking compound to prevent loosening.

 
I have owned two FJRs and when the throttle bodies are properly synched I found them to be as smooth as in-line fours can be. For those who find the vibes objectionable (which is very subjective) th Heli triple clamp helps as well as the Vibranator bar end replacement work. The Vibranators I installed on my Honda 919 eliminated the numb, tingling hands I would get from that bike.

 
Well just took the bike for a 100km ride and definitely the rubber dampers don't work.. In straight roads its ok but in the corners it robs front end feel, feels vague when counter steering into a slow corner (okay I know this is subjective, it's just my experience) At one point I was actually feeling more vibrations than before, well I had the tools in the bike so did the obvious thing, stopped by the roadside, removed the handlebars and removed the rubber parts. They where actually somewhat worn by now causing the excessive vibrations after these few km, so much for this idea then.. replaced the handlebars, and it was much better.

Yes the vibrations are very objectionable as it's a personal thing, some people don't get bothered, others do, simple as that. Will try the TBS next, but again I say that my FJR is very reasonable as is. What helped a lot also was the throttle spring unwind, the vibrations remain the same but as you don't need to grab the grip as strong, you don't feel them as much.

Vasco

 
Hmmm, my 06 had Throttlemeister's on it when I bought it and I've never been bothered by vibration. The 94 Honda F2 I used to have would put my hands to sleep in a half hour!

 
Vasco, I like your style!

I will admit to rolling my eyes at the beginning of your truss rod solution, but you carried it off with a real touch of class with the black tubing and mount for your GPS!! B) Glad it gave you some improvement.

It is refreshing to see someone "thinking outside the box" with a fresh approach to your problem.

And by the way, no need to apologize for your command of the English language... even the "techincal bits". Trust me when I say you wouldn't want to see me try the same in Portuguese! :eek:

Just for chuckles, how many languages are you conversant in? Here in the US of A, most of us are lucky to squeak by in our native tongue. :p

Rock on, mi amigo! (A little Spanish thrown in for a Cosmopolitan touch)

Don

 
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