Excessive vibration on deceleration.

[Owenator]

Hi there,

I'd be grateful if any of you guys could share your thoughts on a recent issue. XB12R 2009.

Last weekend I changed the primary oil and checked the primary chain tension, had the rear fairing off to change the indicators, and undid the rear axel and torqued to spec as I recently had new tyres on and saw the shop did the axel up way too tight.

Now when I ride the bike I get excessive engine vibration through the seat / pegs when decelerating. It's not that there a problem with the engine, just the vibrations being passed through the frame. My guess would be something like the isolators or engine mount but I really hope not. They all look fine from what I can see, the rubber still looks plump and is not perished or discoloured and when I wobble the tie bars there is a small amount of movement due to the rubber mounts but no knocking. The front engine mount is fine and looks to be doing it's job properly (had this go on a previous bike so kinda know what a bad one feels like).

There is no play in the swingarm or rear wheel bearings, nor anywhere else I can detect.

I've double-checked the primary oil level and chain tension and both are good.

Vibration is definitely more noticeable at lower speeds and as the revs drop from about 4k it gets stronger. Vibrations are also stronger with heavier engine braking.

It just seems odd that it came on suddenly, but the work I did on it I don't think would cause any of this.

Your thoughts and opinions would are very welcome!

 

[34nineteen]

I would check the rear wheel bearings, as well as the tensioner.


If that axle was torqued on too tight, there is a good chance the center sleeve is crushed and the bearing inner races aren’t being properly supported any more.

I would do this ASAP.

 

[Cooter]

I 100% concur with what Fred G. Sanford said ^^^.

and add... if it is indeed engine RPM related not speed related... I have psyched myself out after major repairs before. Unknowingly being a bit more sensitive to whats going on as I mentally re-hash every bolt I touched and if I tightened it between gulps of beer.

Decelerating and pulling in the clutch the Buell engines do shake quite a bit and it can be unnerving even though its normal always been there.

 

[34nineteen]

I 100% concur with what Fred G. Sanford said ^^^.

I got that reference you jerk! :black_eyed:

 

[Cooter]

Because you're old. And it's time to pass that yard on, to Lamont

 

[Owenator]

Thanks for the input. I checked the wheel bearings and spacer, had a spare set of bearings so changed them. All fine.

On the way home from work the vibrations got a lot worse. turns out it was the front engine mount. I was looking for a collapsed mount with it hitting the bolt, turns out the isolator is screwed at the top. When I checked the torque on my rear wheel I also jacked up the front and did that so I'm guessing that split what little rubber there was remaining.

Anyway, relieved to have found the problem which is an easy fix.

Thanks again for your help and feel free to comment on my next post which will be called "intermittent rectifier / charging issue"

 

[34nineteen]

The front mount was my first guess, but this made me steer away from it. Oh well, live and learn! :up:

. The front engine mount is fine and looks to be doing it's job properly (had this go on a previous bike so kinda know what a bad one feels like).

cvc on here is working on a replacement bushing for the front mount. Search for a recent thread on here about it, if youre interested.