Vibration issue

[Gunnar]

Hello fellow XS650 enthusiasts,

I am having an issue which I don't know what causes it. My 1981 xs650 vibrates like crazy.

I have just finished another tune-up: adjusted cam chain tensioner, adjusted valves, tried adjusting timing with a newly bought strobe light and realized that my model has electronic ignition , and synced my carburetors.

Even after all this, bike, when revved to 3k rpm, vibrates so much that it starts moving on the center-stand. Is that normal? I am not sure what causes it.

Any advice?

 

[gggGary]

They all move (backwards) on the center stand when revved, part of the charm of a parallel twin. Is your bike stock? Carbs synched, compression about the same both sides?

 

[Brassneck]

Yep, center stand racing is one of the side benefits of these bikes.

Any mods to your bike? All of the engine bolts are there/tight? How are you syncing your carbs (What method)?

These bikes vibrate, but a good tuned bike isn't so bad that you can't everything is shaking violently on it...just a nice rumble. Hit the throttle and the torque will get it moving though.

 

[Gunnar]

The bike is stock as much as I know.

I have been slowly restoring it bit by bit over the last year. I have cleaned carbs last year and put new jets from mikes. I have synced them using a tool I built with two bottles filled with fluid. I have adjusted it to the point where the fluid stays on the same level when I rev the engine at around 3k rpm. Can't do more, because bike stars dancing.

Is there a good information on the location of engine mounts and the torque settings? There might be some issues with it and I would like to check it, I just don't know where to look.

I don't have a compression tester so I never tested the compression of each cylinder.

Just came back from a ride and my bottom is still vibrating...

 

[louis]

Dancing on the center stand is normal mate, can you stop it moving by putting your knee on it when you rev? I wouldn't go looking for a problem that doesn't exist.

 

[cycleranger]

Both pistons rise and fall together.
Big twins vibrate.
If you've only ever ridden modern bikes then I guess this could come as a shock.
Butt vibration is a feature.
On longer rides the rest of your body will go numb as well.

 

[Brassneck]

Is there a good information on the location of engine mounts and the torque settings? There might be some issues with it and I would like to check it, I just don't know where to look.

Yep, tons of info...The upper left search box "Google Custom Search" is a quick way to find threads on just about everything.

I searched the term "Engine mounts Torque" and got lots of info...this being the first:
http://www.xs650.com/forum/showthread.php?t=19170

You may want to post a video of your bike to let us see how bad it vibrates.

 

[Gunnar]

Thanks for all the replies guys. I will check engine mounts and then will post a video about the bike. It's my first ever motorcycle, so I am not sure what vibrations are normal. That's why I am asking you all.

 

[retiredgentleman]

Your bike is completely normal. The vibration is just the way it is with these bikes.

If I need to test the engine running at higher rpm. I put a rubber mat under the centre stand and that stops the bike from walking backward.

 

[jaybird51]

Have an 81 myself and is tuned just fine. Does the same thing as yours. What we own is the Japanese version of an industrial paint shaker. Ride it and have fun

 

[TwoManyXS1Bs]

... I am not sure what vibrations are normal...

http://www.xs650.com/forum/showpost.php?p=437401&postcount=16

 

[fredintoon]

Hi Gunnar,
to expand on cycleranger's post, the XS650 is a 360º parallel twin and as such, the pistons go up and down together.
As far as the balancing dynamics are concerned, it's a big single.
Big singles CANNOT be balanced.
Us XS650 addicts will tell you, that ain't a defect, it's a feature!