Ok so Im on the Dyna forum a lot since Ive now got one in my stable....Mrs found her an anniversary FXDC and fell in love with the paint scheme. On her first break in ride she pulled up next to me at a light and said, hey I need you to test ride my scoot for me, theres a hellatious vibration in higher gear/RPMs. I read where people are trimming the top of the front engine mount rubber so I told her, yeah I read that was an issue but waited to see if your bike did that. I trimmed it and she stated it took about 75% of it away. I figured, cool. The other day I adjusted her clutch pack and decided to take it for a spin and damn if I eliminated 75% of it away and still feel the vibration as much theres got to be others who must be feeling it also, what the hell is that all about or is it I am spoiled to the four mounts my RK has and its the nature of the beast that uses only two mounts. Any solutions to this very peculiar development from anyone?

 

I'll let you know in a few weeks. I've tried all the adjustments like shimming/trimming the motor mount, with a new mount, checking alignment etc. Now it's apart getting a different chain tensioner, new compensator, bearings etc for the primary/transmission. Will see what that does. Next up I'm going to be testing out an entirely new front motor mount that a British company has developed that specializes in chassis mounts for vehicles. They've put a lot of R&D into the mount so can't wait to see what it does.

If none of the above does anything then well. .nature of the beast. Keep in mind the exhaust mounts to the transmission which is part of the engine. Different exhausts have different inherent vibrations they will impart to the frame.

 

Ive never heard of someone trimming a motor mount on a dyna. They like to shake at idle but off the line they should be smooth as silk. I can see in my mirrors perfectly at any speed off the line

 

after 4500 rpm or so my fatbob starts to vibrate. i consider it my shift indicator.
remapping got rid of most of the vibes between 2k and 3k. never had a problem in the 3k to 4500 range.

 

It does vibrate the worst right at the shift points and after 70-75MPH.....just wonder if anyone has a fix, here I'm promising the Mrs now that she has a 6 speed instead of POS Metric 5 speed, she wouldn't be able to hear the engine at 80MPH like my RK that has the same engine and I don't like being a liar.

 

Mine is just the opposite. It is very smooth at higher rpm's(3500-5000),I actually find myself staying in a lower gear much of the time just to enjoy the lack of vibration.

 

what exactly are we considering high rpms? and where are your shift points.

70 in 6th is 2500ish rpms
70 in 5th is 3000ish
70 in 4th is 4000ish
70 in 3rd is 5500ish

when i picked my fatbob up it i never used 6th until i was doing 75+ because of vibes.
since remapping i can ride it down to 50. the vibes doing 70 in 3rd are expected.
changing from the stock tommy guns to a propipe made a little difference. but i really think the stock map is far too lean at the low rpms. at what your feeling is the engine lugging

i'd be interested to hear if the op still feels the vibes in 4th at 70. or 5th at 80.

 

the same with my bike. the higher the rpm the smoother it gets

 

Let me give you some perspective. I owned and enjoyed seven different BMW twins from 1974 to 1995 and rode a few hundred thousand miles on them. My Superglide is just as smooth as those Beemers above 3000 rpm's but they were of course smoother overall.

 

trimming the front motor mount when it starts sagging is harley's answer to fixing the problem .....I noticed my vibes decreased somewhat when I replaced my primary chain tensioner. I am using a hayden unit now and really like it. Always going to be some vibration in the dynas but I dont find it unpleasant at all. Of course I started out with a 94 sportster that could rattle your fillings out of your head at freeway speed.. LOL good luck.