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[JaimeC]

In my time, I've owned three belt-driven motorcycles besides my current Zero; all three of them Buells.  I'm a little curious about the Zero's belt and why it needs so frequent adjustments.  As some background I would first like to point out that Zero's CTO, Abe Askenazie, worked for Erik Buell back when the company was still in business and owned by Harley Davidson.

My first Buell was a 2000 M2 Cyclone, which used the same Gates belt preferred by Harley Davidson.  That bike required occasional belt adjustments but they really weren't all that frequent.  I traded that bike in with 30,000 miles on the original belt which was still in good shape.

For my next two Buells (the XB12Ss Lightning Long and the 1125R), Buell had switched from the Gates belt to one made by Goodyear.  He had also engineered a "constant tension" roller which kept the tension on the belt constant no matter the swingarm position.  Typically, on a belt driven motorcycle, the belt is under the most tension with the suspension compressed, and the least tension with the suspension at full extent since the axis of the drive pulley is not the same as the swingarm pivot.

That last bit is important, because our Zeros DO have the drive pulley in line with the swingarm pivot, so the belt theoretically does not undergo the same changes in tension as a Harley Davidson, even without the constant tension roller Buell used.  Those Goodyear belts used in the 102 bhp Lightning Long and the 146 bhp 1125R were designed to last the life of the motorcycle and never needed adjustment.  There weren't even any adjustment screws on the swingarm.  By the way, one thing ALL belt-driven Buells had was upper AND lower belt guards.

So... since Abe is very familiar with the Buell belt drive system, I'm wondering why we have these belts that require constant checking and relatively frequent replacement?  And why there is no lower belt guard?

[MrDude_1]

The belt is a sore point for me because I really want to recommend an FXS to some friends. As it sits now, they would break it.
I also have a Buell Firebolt  XB12R in the garage. Its like the exact opposite to the SR... just as a FXS would be the opposite to my CR500 supermoto.

I really feel like they THOUGHT they could use a narrower (and thereby less drag, and higher efficiency)  belt because the motor does not pulse, there is no clutch jerks, or drivetrain lash.
The reality is that while the motor output is smoother, the environmental input has not changed. Potholes happen. Traction losses and recoveries happen. These shocks to the drivetrain can snap the belt.  Then theres the usual belt worries of rocks and sticks. as you mentioned, buell handled this with guards, but they also had the top of that roller up high. This made the belt bend upward and kept it from going low near the front of the wheel.

I can accept the rock/stick damage... but the spinup/shock belt snapping just ruins the FXS for me. I really want to say "buy this guys... its silent, and theres no chain and we can all go wheelie and hit some jumps... but it wont take the jumps, and without a clutch you're limited to power wheelies.  (for those that dont fool around in such ways, the short answer is, a power wheelie will wheelie but you're moving fast, a clutch wheelie will lift the front up, but you can be very slow, or even stopped. One is foolish to do in a confined safe area, the other is low speed fun)

While I miss clutch-ups, I can live without them, and they can too.. but when you cant even hit a speedbump without worry.. eeeh.. I cant promote that.

[togo]

Also, as I learned recently, a belt too tight will break a belt.

Next time I hear chirping, I'm checking my tension right away.

[Richard230]

The only time I have to adjust my belt is when I replace the rear tire of my 2014S.   

[togo]

I should have done it when I replaced mine.

[JaimeC]

I check my belt every couple of weeks.  Sometimes I find it just fine.  Sometimes I find it tight, and this last time it was WAY loose.  All the adjustment bolts and nuts were tight so I don't know what is going on.  On my Cyclone, the belt only ever got tight and I had to occasionally loosen it.  As I stated above, the other two Buells never needed belt adjustments (and there wasn't a way to do it anyway).

[MrDude_1]

I check my belt every couple of weeks.  Sometimes I find it just fine.  Sometimes I find it tight, and this last time it was WAY loose.  All the adjustment bolts and nuts were tight so I don't know what is going on.  On my Cyclone, the belt only ever got tight and I had to occasionally loosen it.  As I stated above, the other two Buells never needed belt adjustments (and there wasn't a way to do it anyway).

check your swingarm bearings, wheel bearings, and motor bearings.

[Ireek]

Why not go for the chain conversion?  I know your selling point to your buds is the belt drive, but to me, the biggest selling point would be the electric part of it.

[Shadow]

I check my belt every couple of weeks.  Sometimes I find it just fine.  Sometimes I find it tight, and this last time it was WAY loose.  All the adjustment bolts and nuts were tight so I don't know what is going on.  On my Cyclone, the belt only ever got tight and I had to occasionally loosen it.  As I stated above, the other two Buells never needed belt adjustments (and there wasn't a way to do it anyway).

Factors I'd like you to share your thoughts on:
1. Temperature. The belt is tighter in warmer environment and looser in cold.
2. Tolerance of round on the rear pinion. The rear pinion is allowed to be out-of-round enough that at different portions of its rotation the belt tension will be different.
3. Alignment of the belt on the rear pinion. There should be a 1mm gap to either side of the belt such that it is centered over the usable portion of the rear pinion.
4. Life of belt. A new belt will experience swelling of the rubber on the inside portion which will lead to a tighter belt over time, and I found this to continue up to the initial 5,000-10,000 miles.

[JaimeC]

1. Temperature:  I haven't noticed any correlation.  It's been pretty consistently hot lately and I check the belt before going out (not after).
2. Tolerance of round on the rear pinion:  I put the bike on a track stand when I check the belt so the wheel rotates freely.  I also spin the wheel and check at multiple points just to be sure.
3. Alignment:  I'll double check... I THINK my belt is right up against the "lip" on the rear pulley.
4. Life of the belt:  I have 13,000 miles on the belt now.  This variance in tightness has been going on for awhile. Visual inspection shows the belt still appears to be in good shape; no missing teeth, no fraying of the outer carbon/kevlar fabric.

[Shadow]

,,,
3. Alignment:  I'll double check... I THINK my belt is right up against the "lip" on the rear pulley.
...

With the rear axle nut "snug" but not completely tightened, roll the rear wheel in a forward direction and adjust the alignment so that the belt is flush with the inside (not-lipped) portion of the rear pinion. When you torque the rear axle nut to the correct specification per the owner's manual you will find that the alignment changes such that the belt is now centered as described with 1mm gap to either side.

[JaimeC]

,,,
3. Alignment:  I'll double check... I THINK my belt is right up against the "lip" on the rear pulley.
...

With the rear axle nut "snug" but not completely tightened, roll the rear wheel in a forward direction and adjust the alignment so that the belt is flush with the inside (not-lipped) portion of the rear pinion. When you torque the rear axle nut to the correct specification per the owner's manual you will find that the alignment changes such that the belt is now centered as described with 1mm gap to either side.

AHA!  That might be it.  I'll check on it later and report back (I THINK I brought my torque wrench from my old place).

[BrianTRice@gmail.com]

Wow. I do not adjust my belt unless it's misaligned or far out of its tension band. I really tend not to adjust anything on a bike until it really demands it. I don't even measure belt tension more than a few times per year.

I have original belts on my 2013DS and 2016DSR each at about 21k miles right now. I've only adjusted the belts when I've had to remove the rear wheel. My dealer hasn't reported an adjustment need every time I ask.

[JaimeC]

Well, the belt is right on that rear flange, but I have no idea how to adjust it from side-to-side... only the tension.

[DPsSRnSD]

Well, the belt is right on that rear flange, but I have no idea how to adjust it from side-to-side... only the tension.

I think I was able to influence the amount of gap between the pulley lip and the belt by carefully aligning the wheel using the swingarm marks.