Strange vibration through floorboards on Ultra

[Dettom]

Well I'm not sure how to pose the question but I'll try. I have an 05 Ultra Classic. Some time ago, I started noticing a wierd vibration through my floorboards at speeds around 50 to 75 mph. It seems to be more noticable when the throttle is on. I thought maybe it was swingarm bushings, or a real wheel bearing so I put on a stand and I could detect no play on either. Also, bike handles the same no issues as far as I can tell. I checked steering head play too..nada.
Tire pressure, spot on, shock pressure ok. It almost feells like engine is touching the frame somewhere, although I can't seem to locate where. Also made sure primary chain was properly adjusted, and it was.
maybe its nothing but I dont to spend a fortune trying to isolate what could be a no biggie propositon that I can fix myself. Any takers?

[eagle1]

ck front motor mounts, are bushings in need of replacenet? poly one a option.

[secoleman57]

If it where mine, I'd pick it back up and pay close attention to the tires as I rotated them.

Other than that .. I have no clue seems you've already checked everything I would have thought about.

[eagle1]

had a guy on this site i think maybe harleytalking.com who had this problem. & he found out that the motormount bolts should slide thru easily before they are tightened up. he
has a miss alignment problem . do a search.are the ft tires worn or cupped. put the ft wheel in the air , spin the wheel & use chalk to see if
the wheel is miss aligned.see the service manual on ft. tire install etc.

[SCHMIDTYS]

If the front motor mount is bad the bottom of the engine case can contact the left frame rail. You should be able to slide your finger between the case and frame rail below the left floor board. Inspect the motor mount from below the front of the engine.
Also check to see that the kickstand rubber snubber is in place or the kickstand can make contact which can be felt in the floor board.
Also inspect the top motor mount, those bolts can come loose or even fall off.

[Dave63]

Funny to read this.....I had the same issue. 2005 Classic. It was my running boards. I finally found it when I put on newer, 2006 boards. The part number was different but I believe that was just because of new rubber inserts, not the design.

I checked my motor mounts, swingarm bushings.....

Tighten the moutning hardware for your floorboards.

If they move up and down freely, they make a "knocking" feeling on the frame mount arms, that drives you crazy. I noticed it especially when hitting bumps. Mostly the left one.

I replaced the kickstand snubber...... nope.

I replaced the kickstand spring...... nope.

I wrapped tape where I thought the kickstand may be hitting..... nope.

If all your other stuff is ok....tighten the small allens and 7/16" nut (x2) on each board.

[SCHMIDTYS]

Another thing to check would be the rear muffler hangers, the rubber isolators wear out and can cause vibrations.

[Dettom]

Thanks, guys. Never thought about the kickstand rubber bumper, but its still there. Motor mounts, I can see the front one, but don't know where the back ones are. Floorboards seems tight and no slop. I'll check the muffler hangers although I have a Rinehart system so I'll make sure it doesnt contact the frame anywhere. Other than that, it may not be serious but it just bugs. I hate when things don't feel "tight". Worse comes to worse, I got a good mechanic and I'll take it in and have him sort it out. Thanks again.