Low end vibration

[dakota]

I seemed to have developed a low end vibration on my ’04 FJR with 43K miles on it. When I say “low end” I mean I feel it in the lower part of the bike, mostly in the foot pegs and in the saddle, with no effect on the handlebars. It happens at around 4500 rpm and only on the way up (acceleration) not coming down. This happens under all acceleration modes, easy to hard. The bike feels completely normal until I get to around that 45K rpm range. It will vibrate until I move through that range and then returns to normal after that on the way up. Is this sounding like a driveshaft problem? BTW, I am the original owner of the bike, so I am very aware of what it should feel like. This is a new feeling.

 

[Fred W]

If the vibration is engine speed related, and happens at the same ~4500 rpm regardless of which gear you are in, then no it would not sound like a drive shaft issue. A driveshaft issue would be road speed related regardless of what gear you were in.

 

[dakota]

If the vibration is engine speed related, and happens at the same ~4500 rpm regardless of which gear you are in, then no it would not sound like a drive shaft issue. A driveshaft issue would be road speed related regardless of what gear you were in.

Thanks for your insight. After I posted I went for a 60 mile freeway test drive. I began to realize that it is probably not a DS or any kind of tire issue as it is totally a RPM related issue. I assume it happens in all gears because I get it at 4500 rpm in 4th gear as well as 5Th. I also noticed that it doesn't completely go away after passing through the 4400-4600 range. It just becomes less noticable until somewhere around 5500 rpm (I think) when it spikes again. Best guess... anyone???

 

[Fred W]

There are a couple of possibilities that come to mind:

First thing I would do is to check and/or adjust the throttle body synchronization. I've documented a way to check /adjust the throttle plates (as well as the idle air bypass screws) called the Really Definitely Completely UnAuthorized TBS. My experience with this procedure is that it has the greatest effect in the exact same rpm range that you are experiencing vibration in.

The second thing that I'd do its to loosen and then re-torque the engine mounts. The reason I would think this might be worth looking at is because you mention the vibration is in the pegs, and not the bars so much. One way to identify if this is the culprit is if you are riding along at the vibration rpm and you notice that the vibration comes and goes when you ride over dips in the road. The engine is a part of the structural frame of the bike, which does flex some over bumps.

 

[dakota]

There are a couple of possibilities that come to mind:

First thing I would do is to check and/or adjust the throttle body synchronization. I've documented a way to check /adjust the throttle plates (as well as the idle air bypass screws) called the Really Definitely Completely UnAuthorized TBS. My experience with this procedure is that it has the greatest effect in the exact same rpm range that you are experiencing vibration in.

The second thing that I'd do its to loosen and then re-torque the engine mounts. The reason I would think this might be worth looking at is because you mention the vibration is in the pegs, and not the bars so much. One way to identify if this is the culprit is if you are riding along at the vibration rpm and you notice that the vibration comes and goes when you ride over dips in the road. The engine is a part of the structural frame of the bike, which does flex some over bumps.

Fred,

Thanks for the input. These things are mostly beyond my capability to perform, but they give me proper insight as to what may be causing the issue.

Bob

 

[Canadian FJR]

TBS and engine bolt re-torque is on the list for this winter. Thanks for the pics.

Canadian FJR

 

[HotRodZilla]

I had a vibration just like that on my '07 once. Turned out the sliders in the engine mounting holes were coming loose. Retorqued all of them, and never had it happen again.

If you can't do it, and don't have someone that can do it for (with) you, take it to your dealer. I bet if you ask nice, they'll prolly just do it for you. Its a pretty fast and simple task.