I have a Breakout 114, new to me, it's been in the shop for a couple weeks getting it blacked out and trying to figure out the "shudder".

The symptom is between 55-70, it's very pronounced shudder for 2 sec, then smooth, it's not like a tire being out of balance. The Harley dealer is telling me it's "Normal", and I am not buying it.
I have had many motorcycles over the years, dirt bikes, street bikes, Honda's, Ducati's, Suzuki's, Kawasaki's but never a Harley.

The dealer replaced the front wheel and tire, it's was 5 thousandth out of round by my dial indicator.
I have checked, the alignment(Micrometer from flat to axle hole), the belt(postal scale at 10 lbs, and 45 deg twist test), dial indicated the rear wheel(along center where no rain grooves), and it all looks good to me. Steering Stem has zero play.

It's going back in tomorrow as I cannot stand it. So about the only thing left is rear tire balance.

Any other ideas?
I did "search" to come up with the list of common items...

 

 

Does it happen on acceleration - or at steady speed or specific rpm - or while slowing down? Try to find a steady rpm or speed in whatever gear you use that keeps it happening unless it's a brief transient during acceleration and then maybe again during deceleration. If you can find a steady rpm/speed quickly pull and then release the clutch and see if stays for a bit or abruptly quits by removing the engine from the overall deal with the clutch, and then resumes when the clutch is released. That may help get closer to the problem...engine, drive, or frame/tires.

 

Excellent Point. I forgot to add that detail.

At 55 MPH, steady speed, shudder
At 55 MPH, steady speed, with clutch pulled in, engine at idle, shudder
At 70 MPS, steady speed, with clutch pulled in, engine at Idle, a little less shudder
at 55 MPH, steady speed, with passenger(150 lbs), a muted shudder, still is there, just less

 

Sounds like rear tire/rim/brake/drive pulley assembly might be a factor. More weight might dampen the bad component's action. If you can get it up on a center lift or hung from an overhead via the frame below the seat try carefully running the rear tire to speed and look for visible vert or horizontal movement in the components.

For the rim the lateral and radial runout is 0.030 max. For the tire the same specs are 0.090 max. The Breakout has a big wide rear tire so there's a chance for radial and lateral runout being more of a problem than a narrow tire.

Tire balance may be bad. Any more than about 8-10 balancing weights or ~1.5 oz (it's in the Service Manual) and they should be evenly split on both sides of the rim not just in a line on one side. That would apply especially to a wide tire with the weights further off centerline.

It could be the belt. Roll the rear tire in neutral while off the ground on a stand and look/feel for variability in belt tension as it runs around or tooth damage.

FWIW. I owned a 2018 Fat Boy with the same rear tire. Shook the mirrors in cruise 40-60. The bike didn't fit me so I traded it for a Deluxe which does. Almost no vibes now at any legal speed in any gear. It may take some work on the rear tire assembly to get it smooth.

 

Since the problem is reduced with a passenger, I would look at the rear shock.

 

Adding the bike has 700 miles on it and the same since the day I bought it.
I did dial indicate the rear tire, was within .001 radial runout, did not have a means to remove tire and check for lateral runout on the rim.
I ran it up to speed 55 mph, it was definitely not glass, but difficult to ascertain how to measure anything objectively... - More focus needed here....
Balance Rear Tire - Might be on to something here, there are (8) weights at 5g each on the right side of the rim only, the manual says if more than 42g then evenly distribute along each side.
However, with the new spin balancer's it tells you specifically which side to place the weight. I will ask the dealer to check this tire for balance.

Really excellent suggestions guys, much better than I am getting from Service(nothing wrong with it).

 

Explain your shudder?

 

Shudder = Vibration throughout the bike, 2 sec, then 1 sec off, repeat..

 

Check the lateral runout of the tire if already haven't. Split the balance weights or better yet get a dynamic balance vs. a simple balancer stand roll.

I have experienced a vibration from HD rear tires in a turn caused by exposing the grooves to the pavement. Upright they design the tire to be smooth, but when it rolls over in a L/R turn the vibes can be felt and noise can increase. I don't recall the type of tire but it was on recent HD Touring models mainly.

These new Michelin Scorchers call for a higher air pressure in the rear (42). I'd try playing with that up and down to see if it has any effect.

Edit: Obvious to ask: Have you ridden another Breakout? Maybe the dealer has and they indeed all do it.

Slow recurring vibes or shudder can be created in multi engine installations with two sources. I've done it in marine vessels and multi-engine aircraft when the two sources aren't in synch. Harmonic overlap or whatever it's properly called. In the case of the Breakout it may be from the engine, front tire, and rear wheel for example combining at some rotational speed and intensity.