Bad vibration in '93 FJ

[nsr250]

I've been slowly resurrecting a '93 FJ and have run into a problem. When the tach gets to about 3500 rpm's I get a bad vibration. You can hear it and feel it. Happens whether it's in neutral or in gear going down the road. You can particularly feel it through the bars. The carbs have been rebuilt, valves checked. Any common issues I should be looking for?

Thanks

[Pat Conlon]

The 4th generation FJ's '91-95 have a special rubber isolated engine mount system. On these FJ you need to remove the collars on the front engine mounts to clean and grease them.
http://www.fjowners.com/index.php?topic=3613.0#msg63324

Try this and see if it helps.

For a stubborn frozen collar Randy has a special tool available if you live in the US and are a contributing member. http://www.fjowners.com/index.php?topic=16468.0

[wainot-Phil]

 This is a common problem that can be reduced by doing a few things ,,
1-Make sure that your Carbs have been Balanced using a Morgan Vacuum Balancing Tool our the like
2-Set Mixture screws correctly
3- Remove 2 front engine Mount Bushings and fee them up ,,then Grease and refit
4-Install Rubber washers to the 4 Fairing Mounting Points  
5- Check the Exhaust and Mufflers are mounted correctly
6-Advance timing 4 degrees

The  1st thing I would do is  remove the 2 front engine mount Bushings ,You have to pull the small round steel Bush out of the bigger round  Brass outer Bush ,,
I use the a Bolt the same as the existing engine mount bolt ,but just an inch longer as a puller ,,
You will find that the steel Bush is Rusted tight inside the Brass Bush,,,
It takes a lot of force to brake the Rust seal and get them to slide out ,
Just be careful that you do not pull ,bang or bash the engine mount itself that is cast to the Motor ,,
If your Mirrors go blurred at 3500 rpm ,,fair chance your Engine Mounts are Rusted/Locked inside the outer Brass Bush,,
That is what I found with my  90 ,,92 and 94 model  FJ1200 Bikes ,        ,Best of luck

[ZOA NOM]

I would check the steering head bearing as well.

[oldktmdude]

   I think the others have probably nailed it already but an overly tight drive chain can also cause bad vibrations. Chain may also have seized or tight links.
My money's on the seized engine mounts.
   Regards, Pete.

[nsr250]

Thanks so much for the info on the engine mounts. I'm sure that fix will cure things!!!

[ribbert]

Thanks so much for the info on the engine mounts. I'm sure that fix will cure things!!!

Yep, that'll do it. These models are literally turbine smooth, smoother than most modern in line 4's but they're a shocker when the mounts seize, which they all seem to do.

Everyone says they will do them routinely once fixed, but with the best of intentions, no one ever does. One of the members here did this.....



....the bush is already grooved around the centre for uniform pressure greasing as if it was meant have one in the first place.

[nsr250]

Spent some time this evening removing the bushings. Definitely needed cleaning up. Took quite a bit of effort to remove them.

[Pat Conlon]

Cool, you got them out   ....that's the hard part.  Check back in with us and let us know if it helps.

If not, we'll move on to the next thing on the list....

You mentioned that the 3500 rpm vibes happens when standing still in neutral, as well as on the road in gear. To me, that would rule out driveline (chain/sprocket) or steering issues.

I have assumed you properly synced the carbs when you rebuilt them....that's really important.

Cheers

[nsr250]

What's the best lubricant to use when I reassemble the mounts?

[FJmonkey]

Try this stuff, the winning race teams use it. https://www.rpmracingca.com/proddetail.asp?prod=SynGrease&cat=39

[nsr250]

All greased up and put back together. Only gone on  a very short run but even with it in the garage and revving it up, such a dramatic improvement!!! So much smoother now.

Thank you for the suggestion of cleaning the mounts.

[Pat Conlon]

Your welcome. Enjoy your FJ. Ride well....