Looking for some help. I put a new Custom Chrome front motor mount on my 1987 FXLR , I adjusted the arm to center the engine on the front rubber, but it vibrates something nasty at certain RPMs.

Thinking of putting a stock HD rubber back in.

Any suggestions would be appreciated.

Thanks

 

A softer mount will let the engine shake more which can cause clearance problems but will also isolate the vibration from the rider better than a firmer mount. I guess it's just a matter of finding what works best for your situation.

I have been experimenting with front motor mounts as well, last week I put on the latest stock "D" mount (16207-79D). It does not feel much different than the Velva Ride Mount with my 113" Ultima engine. It is pretty loose and allows the engine to move pretty much at idle but feels pretty good at anything from 2000 rpms and up. The Velva Ride was the similar but because it was a two piece design I was able to add a thin piece between the halves to tighten it up and restrict some of the movement at idle, but that made me feel more vibrations at higher rpms as well, but was not too bad above 2500 rpms. I did not change any of my adjustments, just made sure everything was lined up before I tighten the mount - there is pretty much room for movement in the holes where the mounting bolts go.

I heard you can leave the mounts loose with the bike straight up and run the engine a few seconds and it will find center - but I never tried that. If your engine did not have problems before you changed mounts, I would try to get everything set back to that point and start over.

on edit: The "shaking" , actually a vibration I described is mostly noticed at low rpms, the lower the rpms the more it shakes, therefore a slower idle will shake more than a faster idle. Myself, I prefer to keep the softest mount that does not create clearance problems, I don't care if it shakes a lot at idle as long as the carb doesn't hit the tank and the oil pump doesn't hit the rear brake master cylinder etc.

 

You may already know this, but thought it worth mentioning...

The arm adjustment (link) is for the alignment of the front and rear frame sections. Granted, it's rather forgiving assuming the rear wheel is perfectly aligned with the swingarm pivot. The mounting brace on the frame is slotted (slightly) and the hole in the mount itself is also. So, from the "book" -

With the engine weight on the mount, check that the two mount-to-frame bolts are loose. (I loosen the center bolt now too)

Push the mount outer plate from side to side until the rubber bulge feels even with the outer plate at the bottom side of the mount (outer bulge). Retighten the two mount bolts to 33-38 ft-lbs torque.

Remove the long center bolt. Again, leaving the engine weight on the mount, push the top of the center sleeve fore or aft to center the rubber bulge with the outer plate fore or aft at the bottom.

With the mount now centered, insert the 3/8 bolt and install 2 washers and nut.

So, like Pajoe said, maybe you should start over. That is, put the adjusting link back as close as possible where it was adjusted, loosen the center bolt, and the 2 mounting bolts. Then adjust the position of the rubber mount, in relation to the frame and engine plate until the bulge feels centered with the engine plate and the bottom part of the mount feels centered on the frame.

In the end, the long 3/8 center bolt should slide in and out of the rubber mount with out ever having to "adjust" the link or loosening the mount. Remember, all this is done with the bike on the ground - weight on the rear wheel.

 

Thanks guys, I spent an hour just checking everything again, alignment and found my top motor mounts snug, but not real tight. I got 1/2-3/4 turn on them.
Took the bike out for a ride and it was 90% better, the vibrations stopped going through the frame and the mirrors actually were useful.

So I guess , I was the culprit. Torquing as specified will get ya better results. Got to pay more attention!!