Something in the rear making a popping noise when rolling backwards.

[BloodMoney]

99 RS
Whether I sit on it, or stand beside and roll it, there's a popping noise.
I put it on a jack and spin the wheel, no noise.
I roll forward, no noise.

Sometimes when it first pops going backwards, if you bounce in place it will pop once more, but that's not consistent.
Here's 3 short videos I spliced together.

[Lug Nut]

Remove left pulley cover
inspect belt
Inspect bottom shock assembly
Is there fluid in transfer case?

When riding does it feel or sound odd?

[BloodMoney]

I didn't notice anything when riding.
I shook the heck out of the shock assembly. Plus it does it when I'm not sitting on it, so no shock movement.
The sound is almost definitely coming from rear wheel area, but last year I torqued the front pulley nut, used loctite and bent the tabs over.
I did not check fluid, but I'm not sure that would cause the sound.

Wheel bearing was suggested to me, but again, I'm not sure it would make this sound. Plus, no sound when spinning the wheel by hand.

[Shores]

Make sure there's nothing caught between the rear tire and the fender or between the drive belt and the belt guard.

[Lug Nut]

Not a wheel bearing sound.

[davej]

some of the older bikes had a wheel bearing issue that sounded just like that. The outer bearing race actually spun in the housing.

[BloodMoney]

So I've had to adjust the belt a couple times last year because it would chirp on decel. That has been good for a while now.

Right now it's riding towards the inside of the rear pulley.
I removed upper and lower belt covers so I could see the belt, and inside the front cover.

I loosened the axle and adjusted the left side a half turn looser to attempt to correct the belt path slightly. Now it makes the sound forward and back. Yay me.

I have an event to ride in on the 17th. I really didn't need another issue.

[Shores]

Don't worry about where the belt rides on the rear pulley. It will never ride in the middle and it doesn't matter. What's important is that your rear wheel is aligned in the same plane as the front wheel. Measure from the center of the axle to the center of the swing arm on both sides and make sure they are the same. The belt riding to one side or the other won't hurt anything. It's not a precision piece of equipment, remember that the rear pulley is mounted in rubber cush wedges so it will never be in perfect alignment.

[Lug Nut]

You can't just adjust one side and not measure things. The absolute only way to get your belt tension correct is to do the following. You need to measure from the swingarm pivot Center to the center of the rear axle on the left side and the right side. You need to make your adjustments so that this measurement is the exact same on each side. For example if the left side is 16.75 in the right side needs to be 16.75 in. You also need to sell your belt tension at 10 ft lb at 1/2 in of deflection while bike is on the side stand. That is on the looser side of spec. Specification is .38 to .51 inch while on side ,stand at 10 lb of pressure. Order cheap belt tension gauge off Amazon.

So your rear wheel has to be perfectly centered and the swing arm by doing the measurements left to right and playing with your adjusters until exactly the same and your belt tension has to be at 10 ft lb also. Once you set this you should not have to reset it for much of any reason. These belts don't exactly stretch.

However the sound that I'm hearing does not necessarily sound like just a belt being a little out of alignment to be honest. It sounds like something foreign that's being caught up and spun around.

[Starman]

I adjust my belt by putting the bike on a center stand and spinning the wheel and adjusting until it's perfect. The belt will whine due to rubbing on one side or the other if you don't get it centered.

BTW, I got a new belt when I hit 100,000 miles, just to be safe. The aftermarket belt stretched and wouldn't stay tight, had to get a Yamaha belt. Does anyone notice the construction of the new belts? They're like plastic almost. They don't stretch though!

[davej]

you are gonna have to remove the rear wheel and very carefully inspect everything as you take it apart. You will never find the issue without actually doing something other than guessing. As I said before and again above, some of the older bikes had a wheel bearing issue that sounded just like that. The outer bearing race actually spun in the hub housing. Hopefully I'm wrong but you won't know without inspection. If the bearing did spin the proper fix is a new wheel. But you may get away with peening the hub and using a bearing lock product to hold it in place.

[Lug Nut]

I had no idea wheel bearing could make that specific sound? However the good thing is if you need a rear spoke wheel they're not that expensive or hard to find. In fact I will be removing my rear spoke wheel for my 2003 soon as I am installing a cast wheel.

[Duke]

While checking the belt and wheel bearings, I would check the front pulley out. Even though you checked the torque last year, it would be good to check it out for being loose.

[Brad_G]

While checking the belt and wheel bearings, I would check the front pulley out. Even though you checked the torque last year, it would be good to check it out for being loose.

On the later models the pulley nut is considered a "one-time use" and should be replaced according to service manual. This nut is staked to the shaft unlike the earlier models with the larger nut and washer with tabs. My question is should that washer with tabs be replaced due to lack of tension or can it be re-used?

[Duke]

I have reused the tab lock washer without any issues. If the tabs has been bent over a few times, then you should replace it with a new one.

[Brad_G]

Duke thank you for that input. I picked up an '03 and want to check the pulley nut but wondered if I should get a new washer.

[MikeyC]

I’m with Dave on the rear bearing. Seams to be the left side goes bad

[BloodMoney]

I unfortunately have 3 other vehicles that also need some maintenance. I was going to farm this out to a shop due to lack of time. Nobody can do anything for at least two weeks. The one shop is Yamaha Specific. He said I could stop by Saturday and he'd give it a listen. So I am going to try adjusting the belt tension/ wheel alignment again tomorrow, and then I'll see what he says Saturday.

Unfortunately, I helped organize a Charity Ride for 6/17, and it's very possible I won't be able to actually participate.

I appreciate everyone's input.

[Father Pobasturd]

Broken spoke or stripped spoke nipple.

[MikeyC]

Ooo! Never thought of that.

[Starman]

I was thinking "spoke" because it sounds like when you used to put cards on your bicycle spokes! Could something be hitting a spoke or like you say, a stripped thread or loose spoke maybe?

[Lug Nut]

Broken spoke or stripped spoke nipple.

Hmm didn't even consider that...! Tap on each spoke and see I one/some make a different sound (and visually inspect). 6mm wrench to check tightness of spokes as well...

[davej]

I just look at the pic again and noticed that your exhaust clamp is loose. I'm sure it is not your noise but it needs to be tightened.

[Agpilot]

I have a 99 and a 02 that started that sound. It was as Dave said the wheel bearing was loose in the wheel housing on both..

[BloodMoney]

I just look at the pic again and noticed that your exhaust clamp is loose. I'm sure it is not your noise but it needs to be tightened.

The clamps aren't loose. I'm not sure what you are seeing.

[davej]

I was looking at the pic above and it just looked like it was loose where it is bolted to the bracket. Maybe just camera angle

[BloodMoney]

Well, I accomplished nothing. I redid the wheel alignment, belt tension. Just took it for a ride.
Came back, still makes the noise.

I used the stethoscope.
I had it on the jack.
I put the scope on the brake caliper, drive pulley, center of the wheel hub (thru the spokes), rear shock, front pulley cover. It never sounds like it's coming from what I'm touching.