Hi everyone...its been a while which is good news and believe me I have tried to solve this myself with the manual, the forums and any other online help BUT either I am missing something or I just plain crap at this!
I have a pretty standard 1992 FXDC with an S&S E Carb, all else is pretty factory. Some months back i had to change the rear motor mount and it was vibrating badly at 2k revs. I then though I should change the front motor mount but no real change. Previously I had shimmed the front motor mount with 2 washers and it had all been fine but with this change something seems to have got messed up.

So....I have tried the following:
Bike upright on a stand and front wheel is 90 degrees
Rear wheel is also at 90 degrees
Rear wheel alignment is also ok.

Then, also with the bike on my jack and using a scissor jack to raise/manoeuvre the motor I removed the top engine mount bolt.
I then loosened all the bolts (vertical and horizontal ones) on the the front and back motor mounts.
I started the bike for 30 seconds and then retightened the motor mounts.
Finally I adjusted the top motor mount to fit into the bracket.

It's better but there is still a noticeable and uncomfortable vibration at 2k revs.

Ive read that once everything is loose, including the top mount, yo can find a "neutral" position for the engine but should this be with the bike on a stand and no jack under the motor so its just resting on the frame - I cannot have the motor raised off the frame at both ends as I only have one scissor jack so im hoping it is just resting on the frame?

I have tried revving it in neutral and the vibration is still there so i dont think it is anything wrong in the engine. I am getting very tired of fixing and remobving the motor mounts so can you help with some fool proof method of "centering" my engine please.

Thanks

 

2 things come to Mind..1) O.E. Motor Mounts...as aftermarket are almost always Stiffer...transferring Vibration vs Absorbing it..
2) something is attaching (fixing) the drive train to Chassis that is Not Rubber!! Usually (but Not Always) exhaust tied to Chassis...

 

I use the bent coat hanger/welding rod thingy when checking rear wheel alignment, and these when checking overall engine alignment (link below). One on the front brake rotor and one on the rear rotor. As Racepres mentions, are you using OEM engine mounts? Are they new?

I had the *** end vibration at around 2000 rpm's that went away with a new rear engine mount. Replacing the front was first and did not help much, rear is what fixed mine. Don't have my factory manual here at work, but will double check the alignment procedure this eve.

https://www.harborfreight.com/dial-g...SABEgJzfPD_BwE

 

Thanks Racepres, good catch on the exhaust pipes, thats certainly something i havent looked at so i'll try loosening the connections up and re-tightening and see what happens.
The aftermarket are from Motorcycle Superstore and i have used them last time and they seemed ok so I'll give them the benefit of the doubt. In terms of something attacking the drive train...no idea, certainly dont hear anything, the vibration seems quite clean if you know what i mean. Thanks

 

Thanks YAnkee Dog, yes i have a similar set up with the coat hanger idea. I really think its fining the "neutral" engine resting place before tightening everything up. Maybe i just need to do it all again. I used the procedure from the Clymer manual (I know dont berate me! ) so perhaps the factory manual has something better or can correct something im doing wrong. Appreciate the feedback.

 

Does it vibrate at said rpms when your sitting still or only when riding?

A loose belt will do that and they're supposed to run a lot tighter than one would guess.

 

While a Dyna is Not my FXR, and I have very little experience with Dyna's..
I do Not align like the book...They assume the swingarm slots and (sometimes) marks are perfect...Yet..I know Better.
The Drivetrain alignment (the Heim adjustment links) are to align the Entire Drivetrain straight with the front end, (really to get drivetrain Straight in the chassis. As well as Straight up and Down (90degrees to Chassis)
Once Drivetrain is Straight in chassis...I align the rear wheel to the Belt (or Chain)...ensuring rear wheel is "Straight with Chassis.
If the Belt (or Chain) tracks dead in the middle of the Sprockets...It Must be Straight...If tracking to one side...Pretty sure it must Not be Straight...
One other thing..The Asshats at dealership adjusted my Youngest's Dyna...Crooked...and Belt wayyyy too Tight.. hell, we could hardly Push the Damn thing!!! I am sure too tight (or too loose , thanks t150vej) of a Belt (and Surely a chain) cause undue vibrations...tho only when moving

yes what t150vej says is valid...Too loose is a bad thing too...

 

Excellent advice Racepres!

Stated by Racepres:

"If the Belt (or Chain) tracks dead in the middle of the Sprockets...It Must be Straight...If tracking to one side...Pretty sure it must Not be Straight..."

If I remember correctly, the belt tracks to the side that has the least amount of tension. Just trying to help make things simpler when checking belt alignment.

I have been doing my alignment by the book but I can see the value in your way of doing it.

Someone please confirm this or correct me if I am wrong, but if belt tracks to the left side of the front pulley then the front of the rear wheel needs to be cocked more to the right.

OP, I will try and post the FSM instruction's this eve.

 

I can't see front pulley too good...so I use Rear.. Gettin to be kinda old...and Forgetful, so I simply carank one side or othe to get belt moving direction (left or right) I need it to.. Next time I do this...I need to write this **** Down...Might just make my Job go quicker...But...Then, what will I do with all that time I save????
Sittin here thinkin on it...I sorta think the tight side is Least "gap" so to close a Gap...Tighten (lengthen) that side... But...Honestly I need to Do it to Check!!
Sucks when yer Memory Fails Ya...Like, I cannot remember Free-Play Numbers...Just Cant do it...Been Doing Chains By "Feel" for half a Century...Not enough Failures to make me Change...Belts??? I always go to Middle of Top Run...and Twist. If I can get more than 90 degrees...it is too loose...So Very arbitrary that Hand Strength is an huge Variable... For me? Again, No Failures yet, so.. Ima Leave it!!
Now I'm wondering just How Much Hand Strength it would take to go Past 90 degrees on a Properly Adjusted Belt!!!! Betting More than Most possess!!

 

Here is what I found so far: The top pic in this post is the second page, bottom pic is first page.

Edit: forgot to add, when your doing the losen all engine mounts and run the bike for 5 seconds, the bike needs to be on the ground. Not suspended by a jack at all.