Bad Vibration... help

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Oct 12, 2013 | 07:47 AM

Turbo38gn

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From: Mass

Bad Vibration... help

Morning folks,

I have a 1988 FXLR-C, 98" motor, been just a great rider for years. I recently was on the way home and as so often happens....

I turned onto the main drag.... and guess what happens next.. Bang... 1st, 2nd and click 3rd... what a rush!! Everything seemed fine, get to the next light and stop, take a left and begin to accelerate normally, or maybe I should say normally for normal drivers, as I reach around 3400rpm, a wicked vibration comes over the bike, I can feel in the grips... I back off try it again... same thing. So I pull in the clutch, give it a rev, nothing, feels fine. Only does it under load. I have checked motor mounts, chain, sprocket, just took the primary cover off, chain is a pretty loose, I removed the pressure plate and clutches, the hub is tight on the trans input shaft, the empty clutch basket has lots of movement.

Any ideas, I can't see it in the motor, but is that possible... I'm going to look for my shop manual now to see if there is any info on the clutch basket play..

Thanks ahead for any help or suggestions..

Oct 12, 2013 | 09:06 AM

Tom84FXST

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From: Farmington ,MS

Quote:

Originally Posted by Turbo38gn

I have checked motor mounts,

More than likely, the front motor mount is toast or the top mount is broken...you just can't see it...pretty easy to remove and inspect.

Last edited by Tom84FXST; Oct 12, 2013 at 09:08 AM.

Oct 12, 2013 | 09:59 AM

Turbo38gn

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From: Mass

Quote:

Originally Posted by Tom84FXST

More than likely, the front motor mount is toast or the top mount is broken...you just can't see it...pretty easy to remove and inspect.

Thanks Tom, I checked both out closer. The top is definitely fine and I just removed the lower, I could pry the motor up with my pry bar before removing, have the mount in my hand, it's not broken or rubber torn, but no doubt had 1\4" of upward MOVEMENT.. seems when the bad vib started, it was sudden, after a full out 6,000rpm 1-2-3 shift.

Just a little more info, I recently had a rear tire replaced and the bike was hooking better than ever. The old tire, although not worn much was just dried up and spinning easily on the hard hits. The new Avon is like glue.....

I keep flashing back to a crank pin...? wheels out of balance...

Oct 12, 2013 | 07:30 PM

machinehed

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Joined: Oct 2011

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From: Carlsbad Springs Ontario

vibes.

Quote:

Originally Posted by Turbo38gn

I keep flashing back to a crank pin...? wheels out of balance...

You are a hard rider as described by your 6000 rpm launches ? I would suspect an off center wheel after the tire replacement , unbalanced wheel/tire , or possibly worn motor mounts that are showing there age after the new " sticky " tire has been installed.?

Oct 12, 2013 | 08:44 PM

Turbo38gn

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From: Mass

Quote:

Originally Posted by machinehed

I'm with you, I was looking at the wheel weights this morning, could see where there were some, but I'm thinking that was the spot for the old weights...

Does anyone know how much play is in the outer clutch basket with the clutches removed? I have lots of movement...