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[TheRan]

So I think I've finally discovered the cause of the awful noise my bike makes, the belt is rubbing on the lip of the front pulley. I've read about aligning the motor using the jack screws on the right side (https://www.electricmotorcycleforum.com/boards/index.php?topic=11121.msg104017#msg104017) and I've tried that today and it makes next to no difference unless I'm doing it wrong. Is it just for very fine adjustment (I would assume so considering the motor mount on the left side is rigid) or should I be able to move the belt over a few millimetres?

I have the belt well centred on the rear pulley but I even tried adjusting that so it's hanging off the right side and still the belt wasn't centred on the front pulley. I'm not really sure what else to try, only other thing I can think of would be taking off the pulley and putting a thin spacer behind it but that's far too much effort. Also I think I may have fucked up the motor alignment now because when I roll the bike backwards the belt moves to the right, then centres back up when going forward.

[2020_SRS_Commuter]

Is it possible the pulley wheel itself is worn, and has a smaller diameter on the outboard side?

[TheRan]

Forgot to update this. I did manage to make a minor improvement, I'm not sure if I was adjusting it the wrong way the first try or just didn't adjust it enough. I pretty much maxed out the adjustment on the rearmost jack screws, I could force them more but it would require an unreasonable amount of force on the wrench and would probably just bend the mounts on that side instead of tilting the motor on the pulley side. Just to see how much adjustment range there is I also tried maxing out the front jackscrews to compare and it's difficult to tell any difference visually (unlike adjusting at the rear) however the noise was much worse in that direction. It's still not as quiet as it used to be but it's borderline tolerable now.

Is it possible the pulley wheel itself is worn, and has a smaller diameter on the outboard side?

I wouldn't have thought so, the bike has less than 9k miles on it and there's no pronounced lip on the right side that would prevent the belt from sliding over (which I've seen on some other people's pulleys). I can get the belt to move over if I put a little sideways pressure on it but if I ease of and rotate the wheel it goes right back over to the left.

[ESokoloff]

I came up with a way to check sheave (pulley) alignment on air conditioning equipment that might help you out. 

Start with a piece of string three times the distance distance between the sheaves.
It probably would be best if the belt gard is removed first. 
With the bike on a stand so the rear wheel is slightly off the ground, put one end of the string through the inside of the belt to its halfway point & pull up or down (depending on the best way to do this) while turning the rear wheel.
This will carry the string into the front sheave and allow you to take the two ends and extend them to the rear sheave.
Assuming that the sheaves have the same width, when alignment is perfect there will be full string contact on all sides/surfaces of the sheaves.
If not the same width, there will be symmetry when alignment is perfect.

[rgutt]

Audio would be helpful. I have no idea what you would consider an "awful" noise, but the amount and type of misalignment you could get between motor and wheel on a Zero without specifically trying to misalign them would not make much if any noise. Timing belts run up against their flanges all the time. These belts are notorious for making noise when wet, and any timing belt will be noisy if there is too much tension or damage to the belt or a pulley. Misalignment within reason generally impacts on longevity of the components.

[TheRan]

I must just be unlucky then because my bike has always been far from silent. This is the most recent video I have uploaded and is from back when I would consider the whine acceptable. More recently it has been much more high pitched and before adjusting the motor alignment it was so bad that I could feel the vibrations quite badly through the footpegs between about 25-30mph (leading me to speed slightly on 30 limit roads just to try and keep it quiet).

https://youtu.be/tfoz3dMVkk4?si=2aF2FA36o9cxD5d7

I'll try and get it up on a paddock stand and get a video of it

[rgutt]

That almost sounds like mine when the belt gets wet but not quite the same groan, but that does suggest something with the belt engagement. Looking at the history on this post, it's unfortunate you already messed with the mounting of the motor. Shy of being in an accident, there's NO reason to mess with that and unlikely you'd be able to match what they did in the factory.

How tight is your belt? If I knew nothing else, I'd say your belt was jacked way over tight. And I'd say to check bearings, but I have come across bearings that were on their last leg, could be heard when driving, but that you couldn't feel rolling by hand under no load. It's rare though. You can usually feel a notch at least somewhere around the race.

[TheRan]

Using the Gates app to check the frequency of the belt it's always been within spec and towards the low side, and when I got my tyres changed the shop used a physical tension gauge (not sure what number they set it to specifically but I trust that they did it correctly). When the noise was at its worst turning the wheel slowly by hand I could see that the belt at the front pulley would tilt upwards on the left side slightly where it would ride up the lip on the pulley and then slip down, and I can see polishing on the sides of the teeth on that side of the belt. I've given the belt and pulley a really good cleaning multiple times with little improvement to the noise, the only thing that did help is lubrication.

[rgutt]

When the noise was at its worst turning the wheel slowly by hand I could see that the belt at the front pulley would tilt upwards on the left side slightly where it would ride up the lip on the pulley and then slip down

Ok, that is a GROSS misalignment. Either that bike has been wrecked, someone didn't know what they were doing with the rear wheel alignment, or the motor tweaked in the frame. The belt should not be able to ride up on the flanges ... ever. Moving back and forth under coast and drive is pretty normal. As stiff as the swingarm is, it can still twist a little under load. First and foremost, the shafts must be parallel -- adjustment of the motor and/or wheel axle so that they point in the same direction. Second to that and less important given the span is the offset -- adjusting the motor and/or wheel axles along their axes. There is no adjustment for this at the wheel unless you make shims. This adjustment is built into the motor and done by the factory.

By the way, since you describe seeing the belt riding up on the flange of the motor pulley and given the span between pulleys, I strongly suspect your motor is tweaked. Looking down from the top, if you saw the belt climb up the outer flange, you would need to rotate the motor clockwise and vice versa for the inner flange.

[TheRan]

It's not riding up on top of the flange, it's just the friction of the belt rubbing on it that is lifting it. Then once this friction is overcome it slides back down and this rhythmic motion is causing the vibration and noise. Like I said it's always had a whine to it from the factory and it was bad before the rear wheel ever got removed. I had the alignment on the rear wheel spot on and it was still rubbing on the left side of the front pulley, even shifting the alignment to right so that the belt was hanging off the pulley it was still rubbing up front. The bike has been dropped a couple times but all low speed stuff and nothing bad enough that I would even expect to mess of the alignment and none of the events coincided with the noise getting worse, it just developed over time.

[rgutt]

It's not riding up on top of the flange, it's just the friction of the belt rubbing on it that is lifting it.

This IS riding up on the flange.

[TheRan]

No I mean it's not misaligned to the extent that the belt is riding on top of the flange. The side of the belt is rubbing against it and because it's slightly tapered it's lifting the belt. The edge of the belt is still within the the peaks of the flanges. As you can see from the photo I've posted it only needs to move to the right about a millimetre.

[rgutt]

I'm not sure you understand ... by your description that the belt is lifted by the flange -- even a small amount -- and then falls back down as it rotates around, that is called riding up the flange, and no timing belt should do that. No one is suggesting the belt is riding up on top of the flange. In a fixed center design, that isn't even possible unless those centers were reallllly far apart, the belt was extremely elastic, or there was grossly insufficient tension, none of which apply to these bikes.

And the image does not suggest the belt needs to move a mm to the right. I don't know where people get this idea the belt needs to be centered on either pulley, but it does not. I know Zero says something about 1 mm off the inner flange of the rear wheel. As someone who has to write instructions for equipment I design, I can tell you that number came out of someone's @ss because an instruction needed to be written and some number was needed to give people a target -- and flush against the flange is a poor instruction for reasons that are beyond this post, but you can likely figure it out. The position on the sprocket is irrelevant. The only way that number would be relevant would be if Zero did such a good job of aligning the motor and its sprocket in the frame relative to the rear wheel that 1mm off the rear flange coincided with the point of proper alignment. It's possible, but given some of the recalls I've seen, I doubt they went through that much trouble. The belt just needs to run true between the sprockets. If your belt is being lifted at all by that outer flange then yes, the alignment needs to be adjusted, but when properly adjusted, the belt might very well still track against that outer flange.

It's unfortunate your bike has always made this noise. Was it new when you got it?

[rgutt]

By the way, I went back to your original post ... those "adjustments" on the right side of the motor are not for aligning the motor. That said provides adjustment so that the motor can be rigidly mounted between the sides of the frame with the left side fixed. Without the ability to adjust for width differences between the body of the motor and machined mounting points in the frame, both would end up stressed when the motor was bolted into place. If you tried to change the orientation of the motor using those bolts, you're not doing your motor any favors. The stress on the frame would be irrelevant, but torquing the body of the motor will impact motor efficiency, bearing life, and clearances between the armature and stator.

[TheRan]

Moving the belt a millimetre to the right would stop it rubbing on the flange of the front pulley, I'm not talking about the alignment on the rear pulley where people say it should be 1mm away from the flange. And when the belt is being lifted by the rubbing on the front pulley it's not being lifted equally and staying level, which would only be possible if the belt was really loose (the tension is within spec). It's only the left side of the belt that is being lifted, the belt is twisting ever so slightly.

I'm just going off what the unofficial manual and other people have said, that the jack screws are for motor alignment. If that's not the case then how else am I supposed to get the belt shifted over to the right on the front pulley? Adjusting the alignment at the rear doesn't make any difference. I got the bike ex-demo with barely 100 miles on it and it hadn't even been dropped.