More on Vibration...

Discussion in 'Rack Mounted Engines' started by rossfree, Sep 3, 2008.

  1. rossfree

    rossfree Member

    I've heard about others having vibration at various speeds. I didn't have this problem. I started with a standard GEBE setup and then modified it somewhat by cutting the mounting forks and building parts to hold them to the frame instead of bolting them to the axil. I also extended the engine back further with a longer metal bracket.

    I never had vibration to speak of.

    Until...

    ...my rear tail light broke off. It was mounted to a small bracket bolted to the clutch housing and eventually the vibration of the engine fractured the metal bracket and it went bye-bye.

    No vibration yet... stay with me...

    So I got another tail light and bolted it onto the extended motor mounting bracket. (See Pics) Bingo... I had vibration. During accelleration through mid-speeds, my seat and bike would vibrate excessivly. It would go away when the engine reached it's upper RPMs.

    ****dest thing!

    I haven't made the connection yet. It couldn't really be the light placement... could it?

    I made plans to remove the light and try the bike out. I did it yesterday on the way home from work. With the light removed, the vibration went away.

    I put the light back on this morning (I ride to work in the dark... no way I ride without that light). The vibration came back but it was not as bad. The light is mounted with a bracket that has an oblong hole. I can position the bracket forward or backward by about half an inch. That half an inch makes a difference.

    Soooooo... ponder the evidence folks. I conclude that small changes can make a BIG difference in vibration. If you are having trouble with excessive vibratioin try moving things a bit. Maybe add a bolt to your engine mount and see what it does. I would suggest that vibration is likely exaggerated the most in large flat or long parts such as the long flat engine mount above between the seat and engine. Making small changes to this may eliminate your vibration entirely!

    Happy motoring!

    Ross
     

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  2. flyer1

    flyer1 Guest

    new vibration

    I just finished replacing my rear wheel with the gebe 105g(12 gauge, I think), the spokes are friggin huge, I do not anticipate any trouble with this wheethe l.Anyway I reassembled everything ad thought I actually made improvements,particularly with regard to the belt tracking which is now dead center.But I am now getting significant vibration right at 22mph.Just don't know what it could be,it goes away at 23-24mph.I checked and everything is tight.Have to figure it out and pot.
     
  3. Zev0

    Zev0 Member

    Here's a very good way to check and see if things are moving and going correctly. Start your engine. Stand on right side of bike, tilt bike up on hip so both wheels off the ground. Well, at least the rear wheel HAS to be off the ground. Then give it a little throttle. Watch and listen, a little more throttle, watch and listen. You get the idea. It will pretty much tell you what's going on.
     
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