I look forward to anything someone comes up with, and willing to chip in somehow. I've got a few irons in the fire right now, just trying to make economical improvements to the bike for touring without a ton of custom fabrication (or split the cost/benefit).
Before i removed the pebbles i got into the belt i took a few photos showing where i believe it is most likely that debris would enter the belt. From my brief experience, rocks at a certain size seems most likely to get stuck within the belt. If you look at the attached pictures i have marked the areas i think should be of particular interest when making a belt guard.
I believe the motor cog wheel (1, red) might chew on pebbles falling down from above, either directly from the wheel or those that fall down from the engine (2, blue). Without a proper mudguard, this area gets filled with small pebbles under the wrong conditions. I would guess that this is quite likely what has happened with most of the pebbles i got embedded in my belt.
It is also possible that some rocks would land on the belt going from the motor cogwheel to the rear wheel (3, yellow), but since the distance here is several centimeters, i would guess it is less likely that rocks landing here would stay on the belt long enough to be chewed by the rear wheel cogwheel.
I've also noted that gravel may land on the belt from inside the current rear wheel hugger, as the belt is exposed from the inside as shown in picture 2 (4, red). Last way of entry would be from below the swingarm (5, cyan)- where the rear wheel cogs may chew anything that may enter at that height. I would guess pebbles entering the rear wheel cogwheel would most likely either come from meeting traffic or the front wheel. I'm not sure if it is possible or likely for pebbles from the rear wheel to go there.
Now from what i've seen, i am currently focusing on two things.
A: Prevent gravel from landing in the area around the motor & suspension.
B: Prevent debris gathered in the engine area from falling onto the motor cogwheel.
As an option for later, id might also look at
C: prevent rocks from entering the rear wheel cog wheel.
I have already made a temporary solution (shown in the third picture) that has reduced the amount of gravel landing on the motor with 90% or more. Now i am planning on making something more permanent and durable, but that may take some time. I have ordered a cheap plastic mudguard to see if i can make it fit. http://www.ebay.co.uk/itm/Motorcycle-Black-Outstanding-Rear-Mudguard-Fender-Accessory-Prevent-For-Harley-/251719364694?hash=item3a9ba4b056:g:cYoAAOSw~FNUZyo~
I'll have to see if i am able to make it fit, and look half decent. I guess i can attach it to the existing rear wheel hugger plastic, but i have to come up with some way of attaching it on the sides. If it can be decent enough, i will see if i can make some sort of bracket attached to the swing arm that would extend (or hold a piece of metal that would extend) all the way up to the plastic mudguard i've ordered.
In addition to this, i am looking at the possibility of creating a belt guard for the front area. Now as this may not have to be very big, i hope to make something 3D-printable. I guess it has to be made in a way that it can be securely attached under the current hugger, using the same screw, and it would have to extend above the belt, deflecting pebbles from both the rear wheel area and those falling off the engine. The hard part here is that it should ideally touch the engine to avoid pebbles from falling from it, and it has to be strong enough to sustain wind and have an angle that would deflect rocks from all sides approaching the belt. I have a few ideas to follow, but it will be a rather complex design, likely requiring several attempts of printing.
There are a few concerns i have with creating a belt guard for the front end of the belt.
- having plastic touching the motor might not be great (ideally the part should be metal).
- the swing arm will be moving with respect to the engine, so there has to be space in between.
- creating something that doesnt break (again, ideally metal)
I guess these are my current thoughts about belt guard. Any thoughts or suggestions?