The wear is on the outside of the belt, so it really should have anything to do with the pulleys or contact with the pulleys. Question, how is the belt tension? I'm wondering if your getting some kind of harmonic (vibration) in the belt between the pulleys and the outside of the belt is hitting the inside of one of the belt guards when it's under load?

 

that pretty fine. maybe something is under you sprocket cover

 

Seems like you will be pulling your sprocket cover "real" soon anyway. I'll bet you will find a shiny spot somewhere, or something lodged solid. I don't suspect something "got in and got out" that fast. The pattern is too consistent with debris. This looks like your cover has shifted or something. Maybe something in your belt guard let loose. You will know soon!

 

Check the rear pulley. In years past, I've witnessed big-twin pulleys, separate. They don't split in two, down the middle, but the pulley component comes away from the mounting ring. I haven't heard of Sportster pulley separation, though. Check the pulley bolts for wobble / boogers. That definitive line in the middle of your belt, is most curious. Jack it up, and spin the wheel, listening, carefully. Then, start taking **** apart, and see what's up.
Good eye, and good-on-you for your attentiveness. The belts are extremely durable. My Softail belt, has had a hole for over ten years, created by a pebble stuck in the belt. The hole is small-ish, and in the middle of the belt, but it keeps rollin'. They're tough, but not indestructible.
Let us know what you discover. I haven't encountered such a situation, on a Sporty.

 

Agreed...
I thought the very same thing.
Here's why I did.
https://www.youtube.com/watch?v=eVBV...ature=youtu.be
I was looking for different locations to mount my GoPro and thought I would try out the passenger peg.
If you look at the video at about the 20 to 30 second mark (looking at the extreme left) you will see what I'm talking about.
In my opinion, there seems to be a fair amount of resonance, to the point of hitting the top of the sprocket cover on the way to the front sprocket.

I don't have a belt tension gauge (yet! it's now on the list) but I read about the 45 degree twist method.
Based on that test it was a little loose so I tightened it up.
After doing so, I filmed another video... same thing.
It didn't change a bit.
That shocked me a little.
I thought for sure that was going to be the issue.
Wishful thinking I guess.


Starting to be a consensus...


Hmmm... I'll check the pulley/pulley bolts... after peering behind my sprocket cover.
Hopefully I can get to it tomorrow night.
Thanks for your response.
Yeah, once I find the issue, I'll post with what was found.
It might help someone in the future.
I did a search for this situation and found nothing.

 

To me, imho, it looks like you found the source of your problem in that video you posted. Your sprocket cover seems to only cover that outer half of your belt and the belt seems to be flopping up and down enough to slap the sprocket cover and cause wear to that outer half of the belt. You said you tightened it up and there's no difference though (at least to your naked eye), right?

 

It's an illusion, the sprocket cover fully covers the belt.
Here's another pic...



No difference.
Made another video and it views exactly the same way.
I thought for sure that tightening the belt would reduce the severity... it didn't.

Thanks for responding

 

Well I went out in the garage and looked on mine. No wear on mine, but noticed that under the belt, the master cylinder and crossover frame are potential contact points. Maybe you could check for scuff on that hardware.
You could have had debris get under the front pulley guard also.
One idea you could try is take a crayon to a couple of inches, ride it, and determine if it is still rubbing (and against what).

 

My 2nd guess is that something got in your belt, was stuck for long enough to cause all that wear and then finally fell out. BUT,..you think the drive pulley would be worn as well? I think the drive pulley is steel tho. If the rear pulley is alum this "might" be an explanation as to why one pulley is worn and the other is not.

 

Well, I like Ratwerke's suggestion. Also sounds like bitin bullet and takin off the front sprocket cover will help narrow your search. You could at least cross it off your list and it's very possible that is where your problem lies.