FJRs vibrate. They all do to some extent. You may be too numb to feel it, but it's there. It happens because it's an inline 4 cylinder engine with even firing order, so the two inboard pistons, and two outboard pistons run in tandem. All of the reciprocating masses are in one of two states, similar to how an inline two cylinder engine would.
The designers attempted to nullify the primary engine imbalance with counter rotating balancers, but they are not totally effective at eliminating vibration at its worst, which is typically at around 4k rpm and above.
To make matters worse, in the 3rd Gen engine redesign, Yamaha eliminated the ability to tweak the throttle plates to try and null out any of the secondary vibration due to small differences in fueling at higher rpm, so the 3rd Gens may actually have more vibration at those engine speeds than some of the earlier models.
Designers isolated the 3rd Gen rider from these engine vibration pretty well with the new type of thicker foot-peg rubber covers. And the seat is well isolated from the frame by the fancy rippled rubber bumpers it sits on (ever notice them?). The remaining primary contact point where the vibration can become bothersome is at the handlebars, and this is where I primarily sense "the buzz".
Is it horrible and offensive? No, and no. Does it make riding the FJR long distances (or short ones for that matter) somewhat less enjoyable? Yes, to a certain extent that varies by individual. The pertinent question is: Can the handlebars be somehow isolated from the vibration? And if so, why wouldn't you want to do that?
What started me thinking about this topic is that I recently removed the Suzuki Vstrom hand-guards that I had fitted to my 2014 for the added cooling during the upcoming summer months. At the same time I removed the 1 lb. jumbo bar ends that I had transferred (along with the hand guards) from my 1st Gen to the 3rd Gen. The eye opener was that when I took a highway ride the following day, the vibration level reaching my hands was reduced enough that I noticed it. Not gone entirely, but reduced by maybe half. So somehow, those heavy bar ends were mechanically amplifying the vibration in the bars at that specific frequency.
Well, thinks I, if one weight on the bar end can amplify the vibration, there is probably another one that would nullify it. The trick would be measuring the amplitude and frequency of the vibes and doing a series of experiments to see what combination of weight or weights it takes to null it out.
The other opportunity after establishing the offending frequency of vibration , would be to design some sort of visco-elastic isolation layer / boundary between the buzz source engine and the handlebars. If the vibes never get into the bars we don't have to null them out. That may actually be the easier solution. Of course it could not affect the feel of the steering or it would not be acceptable. But my experiences at work say that vibration isolation can often happen with some fairly firm cushion layers that are of the precisely correct material for the frequency you want to block.
Unfortunately, I do not have an expensive accelerometer at my disposal to measure the vibration amplitude and frequency(s). I tried downloading an iPhone app that has a nifty accelerometer feature (iPhones have some crazy sensors in them, including one for g-force) but the sampling rate of the sensor is too slow to be of much use for this experiment.
I suppose that we could use tactile feedback, but subjectivity is the enemy of a good design process. It would be much better if it could be measured and bench-marked before designing or trying possible solutions.
Thoughts?
The designers attempted to nullify the primary engine imbalance with counter rotating balancers, but they are not totally effective at eliminating vibration at its worst, which is typically at around 4k rpm and above.
To make matters worse, in the 3rd Gen engine redesign, Yamaha eliminated the ability to tweak the throttle plates to try and null out any of the secondary vibration due to small differences in fueling at higher rpm, so the 3rd Gens may actually have more vibration at those engine speeds than some of the earlier models.
Designers isolated the 3rd Gen rider from these engine vibration pretty well with the new type of thicker foot-peg rubber covers. And the seat is well isolated from the frame by the fancy rippled rubber bumpers it sits on (ever notice them?). The remaining primary contact point where the vibration can become bothersome is at the handlebars, and this is where I primarily sense "the buzz".
Is it horrible and offensive? No, and no. Does it make riding the FJR long distances (or short ones for that matter) somewhat less enjoyable? Yes, to a certain extent that varies by individual. The pertinent question is: Can the handlebars be somehow isolated from the vibration? And if so, why wouldn't you want to do that?
What started me thinking about this topic is that I recently removed the Suzuki Vstrom hand-guards that I had fitted to my 2014 for the added cooling during the upcoming summer months. At the same time I removed the 1 lb. jumbo bar ends that I had transferred (along with the hand guards) from my 1st Gen to the 3rd Gen. The eye opener was that when I took a highway ride the following day, the vibration level reaching my hands was reduced enough that I noticed it. Not gone entirely, but reduced by maybe half. So somehow, those heavy bar ends were mechanically amplifying the vibration in the bars at that specific frequency.
Well, thinks I, if one weight on the bar end can amplify the vibration, there is probably another one that would nullify it. The trick would be measuring the amplitude and frequency of the vibes and doing a series of experiments to see what combination of weight or weights it takes to null it out.
The other opportunity after establishing the offending frequency of vibration , would be to design some sort of visco-elastic isolation layer / boundary between the buzz source engine and the handlebars. If the vibes never get into the bars we don't have to null them out. That may actually be the easier solution. Of course it could not affect the feel of the steering or it would not be acceptable. But my experiences at work say that vibration isolation can often happen with some fairly firm cushion layers that are of the precisely correct material for the frequency you want to block.
Unfortunately, I do not have an expensive accelerometer at my disposal to measure the vibration amplitude and frequency(s). I tried downloading an iPhone app that has a nifty accelerometer feature (iPhones have some crazy sensors in them, including one for g-force) but the sampling rate of the sensor is too slow to be of much use for this experiment.
I suppose that we could use tactile feedback, but subjectivity is the enemy of a good design process. It would be much better if it could be measured and bench-marked before designing or trying possible solutions.
Thoughts?
