Drive sprocket/chain noise

[Mitch81special]

1981 special. The noise doesn't sound as bad on the video but have a listen. It sounds like a bicycle with a playing card in the spokes. Seems to me it's the chain hitting the teeth of the sprocket. It's only recently gotten louder. Is this just a worn sprocket or is there somthing else going on?
https://youtube.com/shorts/oEHs0NIjKmc?feature=share

 

[member28833]

I hear it ! Not too alarming sounding to me looking at the sprocket condition

Sounds like the chain may well be rubbing on the chain guide under the sprocket..
Big fat O'ring chain?
Is that nut tight?

 

[GLJ]

You need a front sprocket. From the side wear on it it looks like your your rear wheel is not aligned correctly. Also look at the rear sprocket.

 

[5twins]

Now that you mentioned it, that does look like an awful lot of side wear. But that's an aftermarket sprocket. Maybe it's made stepped like that? Your chain looks pretty dry. Maybe a good coat of chain lube would quiet things down some.

 

[member28833]

Sprocket looks horrible, that sprocket would ruin a good chain very quickly.
Agree that an alignment issue is also likely.

 

[Mitch81special]

I'll order a new sprocket. I aligned my wheels using the string method. I guess that doesn't aline the sprockets though. Is there a better way to check my sprockets are lined up?

 

[BowlingSS]

I would just look from the rear. You should be able to see straight down the chain.

 

[BowlingSS]

I hear it ! Not too alarming sounding to me looking at the sprocket condition

Sounds like the chain may well be rubbing on the chain guide under the sprocket..
Big fat O'ring chain?
Is that nut tight?

The lock needs to be bent over after you make sure it is tight.

 

[member28833]

I aligned my wheels using the string method.

Nice effort! I think a new bike build would perhaps benefit from that even more.
If your swingarm and wheel spacers are all original and installed properly, why not trust Yamaha? I have trusted the rear axle adjustment scale on both sides of the swingarm always and found very little error.
Looking down the chain on centerstand and spinning the rear wheel should confirm how close in chain alignment the adjustment scale actually is.

 

[5twins]

With your physically larger than stock o-ring chain, you'll need to stay with the stock 17T front sprocket size, there's no room to go larger. But if you're going to change the rear too, you could juggle that size a little. A 32T on the rear (2 teeth smaller than stock) with a 16" wheel works really well.

The oil streaks emanating from your front sprocket nut may indicate it wasn't quite tight enough. My '78 always did that and if I remember, I think I torqued the sprocket nut to around 72 ft/lbs. Recently I tightened it a bit more, up to around 95 ft/lbs. That's the value listed for the very early models. I haven't been back under that cover since doing this but I think that may have "fixed" the issue. It seems I'm no longer getting the occasional drip of oil from that area I always used to.

 

[Mitch81special]

So I'm a bit confused. Looks like my chain is a 530. But my sprockets say 540. Wouldn't a 540 sprocket not fit in a 530 chain? Also looks like I should probably just replace both sprockets. So should I maybe go down a size in chain?
Looking down my chain it almost does looks slightly out of alignment? (to my inexperienced eyes). But I don't want to change it and throw my wheels out of alignment.

 

[5twins]

I don't think there is a "540" size. That "5401" on your sprocket is probably just a part number. You can get JT sprockets off eBay for a pretty reasonable price and they're a pretty good, well known brand.

 

[Mitch81special]

You can get JT sprockets off eBay for a pretty reasonable price and they're a pretty good, well known brand.

Thanks I'll do that. Does going down to the 32 tooth change rpms?

 

[5twins]

Yes, it'll lower the RPMs by a few hundred at cruising speeds which will make it nicer and smoother on the highway. But, it's not a big enough change to hurt your take off power in the lower gears.

 

[member28833]

Using the 17fr & 32 rr sprocket combination on a Special, a 104 link chain should end up with the rear axle right in the middle of swingarm adjustment scale with proper chain tension set.
I suppose that is a good place to start and would not expect to run out of adjustment as the chain and sprockets wear in.

 

[Mitch81special]

With your physically larger than stock o-ring chain, you'll need to stay with the stock 17T front sprocket size, there's no room to go larger. But if you're going to change the rear too, you could juggle that size a little. A 32T on the rear (2 teeth smaller than stock) with a 16" wheel works really well.

I'm looking at ordering some sprockets and thanks for the advice here, I'll get a 32 tooth rear. But i also feel like I should just replace the chain as well. Should I go down a size to a 520 chain? Just for clearance?

 

[5twins]

No, that would require all new 520 sprockets. As long as you stick with the stock 17T front sprocket size, there will be room for an o-ring chain. I have one on my '83, stock 530 size, and it fits fine. My gearing is the stock size 17T on the front and a 32T on the 16" rear wheel, and I love it.

 

[hovel]

Is there a better way to check my sprockets are lined up?

Motion Pro sells a slick little alignment tool. I have one and really like it.

 

[Mitch81special]

Motion Pro sells a slick little alignment tool. I have one and really like it.

This one? https://www.partzilla.com/blog/moti...EmS3IB6NomuFYVl3W2ZsvlesofY3fcMEaAtCtEALw_wcB

Looks very slick. I'll be changing my sprockets and chain here pretty soon and this looks like it might come in handy.

 

[650Skull]

A peice of string would be cheaper and does the same job