Vibration

[DavidTX]

  I am having a bad vibration/wobble at 77 MPH. The bike is a 1983 V65. The vibration seems to be in the front end.  I have replaced the bearings in the stem and also the front wheel bearings.  Balancing and even replacing the front tire doesn't help. Any recommendations would be appreciated.

[roboto65]

Has the front brace been modified.I am not real familiar with the V65 does it have one if not it might solve the problem

[trapper]

I'll just take a stab at a couple of things David...

To answer Allen's question, the V65 does have a Fork Brace.  If this were broken, you might experience some wobble in the front end.  Another possibility is that the Fork Tubes may have somehow become "twisted" in the Triple Tree Clamps resulting in mis-alignment causing the tire to not track straight.  Are you seeing any uneven tire wear?  Also check to make sure that the Fork Tubes are at the same height in the Clamps.  Is one Tube protruding higher out of the Top Clamp?  This would also cause some alignment problem. 

Hope this helps you...

[Greg Cothern]

Seen it a few time and the folks whom I knew had the problem cured it with new tire technology.  John maybe on the right track?!!

[DavidTX]

I even installed a stainless steel plate and that didn't help. Also replaced the springs in the front end.  Old tires were Avon, rebalanced and still had the vibration so replaced tires with Pirelli Demon.

[lragan]

I even installed a stainless steel plate and that didn't help. Also replaced the springs in the front end.  Old tires were Avon, rebalanced and still had the vibration so replaced tires with Pirelli Demon.

We are all waiting for the other shoe to drop.  Did the Pirelli fix it??

[Smoked U]

Front rotor(s) warped?

[TLRam1]

Did you add or change the air flow up front, lowers, windshield, etc.

[DavidTX]

The tire did not fix the problem.  Windshield has been installed since I bought the bike.  Of course I have also had the shimmy since I got the bike.  Shimmy is the same no matter what gear it's in and at the same speed.  It seems to be worse on de-acceleration than it is when accelerating.  I will check the front rotor again.

[TLRam1]

I posted this on another forum, here is one response. This is from a vintage motorcycle forum where they deal with this stuff quite often, but there not familiar with this in particular on this bike. 

Iat 77mph is the speed at which engine vibration is in resonance with the frame and or forks and is causing that effect.

If the motor is rubber mounted, check to ensure that nothing is loose or worse, binding. For example crash bars which are fitted to the engine mounting bolts causing it to act as if it were rigidly mounted.

Check all other engine mounting bolts to see that they are tight enough. check to make sure that any spacers between the rubber mounts (if it has them) are there and the mounts are over tightened.

Next check for carb synch and make sure that the motor is running as smooth as possible.

Check compression on all 4 pots to be sure there isn't a low cylinder.

If all that checks out the next step is to change the resonant frequency. Remove any non standard parts like fairings or crash bars or sissy bars and see if one of them is the issue.

If all else fails try different bars to put more or less weight over the front wheel and/or fit a bar snake to change the resonance through the bars. It might also dampen out all the resonance.

[DavidTX]

Terry, thanks for the information.  I will certainly check those items.  I will update after checking and hopefully correcting the problem.

[TLRam1]

Some of this may not pertain to your bike but there was a few different ideas to look at.

[TLRam1]

More ideas,

One other thing, it may not be originating from the front end as it feels like it is. My H1 felt like it was falling into any left hand turn so badly it was unnerving. I replaced the swing arm bushings, rear wheel bearings and rear tire, and presto, it stopped falling into left handers.


I'm thinking along the same lines as Wayne. The Magna is a shaftie, so it doesn't have a traditional swinger-bolt. It has short bolts on either side that must be adjusted to maintain the proper tension. The problem could be in the rear end.

Could it be in your shaft drive....