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Chain slack adjustment

Ocho

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May 29, 2018
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242
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Austin
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Jorge
Hey guys,

I finally adjusted the chain slack by myself after purchasing the torque wrench and hex bits needed to tighten everything correctly. However, a simple procedure ended up costing me a couple of hours of trial and error.

There were some things that I'm uncertain about and wanted to see if you guys can provide some insight. Bear in mind my chain is on the left side of the motorcycle.

  1. What exactly is happening when I adjust one side or the other? What parts are moving?
  2. It seemed the left side was solely responsible for chain slack, no matter what I did the right side seemed not to do much as far as I could notice. I assume the right side had to do more with alignment? Also, the right side doesn't seem to adjust much, if at all, in one of the directions. I don't know how to explain this, but the right side seemed to lose tension really quickly if I went one direction.
  3. I used the technique shown in one of the Motorcylists youtube videos to put a rag in between the sprocket and chain when tightening everything up. Is this to prevent over tightening stuff? How much do I need to tighten the lock nuts? My user manual only had torque tension for the axle nut.
  4. Is it normal that my chain slack varies from 30mm all the way to 45mm? Spec is between 25-35.
  5. Once on the center stand, I put it in first gear, and the chain seemed to have varying degrees of noticeable tightness. It even rattled whenever it reached the tighter spots (I assume). This appeared to be gone after some cycles though.
  6. How straight does the chain need to be? I used the Motion Pro's tool to check chain alignment, and it looks pretty straight, but does it matter if its slightly to one side or the other?
  7. What would be a simple way to know if I did this wrong? I have yet to ride the bike.
Here's some videos, one of the chain moving and the other one was me checking the alignment.

https://streamable.com/imi7k
https://streamable.com/ztbzp

PS. I cleaned and lubed the chain after.

Thanks!
 
Joined
Feb 10, 2015
Messages
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Location
Fm 1681, Stockdale.
How many miles do you have on the bike? Chain should move smoothly throughout its rotation.

You always want to adjust both sides simultaneously, and the same amount. So your rear wheel is straight in the swing arm and your bike runs straight down the road.

If your wheel is straight your chain SHOULD be straight(barring other issues).

When you adjust, you need to make sure the axle is pressed firm against the adjusters. That's where the slack comes from.

Sent from my SM-G965U using Tapatalk
 

mitchntx

Follower of Rev. Doug
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Granbury
Jorge,

1. The adjusters slide the axle

2. The sprocket side will move and take up the slack. The opposite moves to align the axle/sprocket.
Moving one will affect the other.

3. The rag is used to ensure the axle is firmly against the adjustment stops.
A lock nut, just keeps a bolt from turning.
Doesn't take much torque to accomplish that.

4. Slack ... sounds as if your chain is too dry or worn.
I've heard so many folks claim that a sealed o-ring chain needs no lube.
While a true statement ... the engaging of the sprockets do need lubrication.

5. See #4. It went away once the chain warmed up

6. Alignment is critical to prevent chain and sprocket wear.

7. Noise, rattling and asking questions on the interweb ...

Clean and lube first, then adjust.
 

Tourmeister

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1. What exactly is happening when I adjust one side or the other? What parts are moving?
:tab The goal is to have the front and rear sprockets and the chain all aligned so that the chain feeds onto the sprockets straight and not at an angle relative to the plane of the sprockets.

2. It seemed the left side was solely responsible for chain slack, no matter what I did the right side seemed not to do much as far as I could notice. I assume the right side had to do more with alignment? Also, the right side doesn't seem to adjust much, if at all, in one of the directions. I don't know how to explain this, but the right side seemed to lose tension really quickly if I went one direction.
:tab Ideally, BOTH are affecting your chain tension, it is just more obvious with the left side. Getting the right side correct means that the axle of the rear wheel is perpendicular to the plane of the sprocket/chain combination. If the right side is to far forward or back, that causes an angle between the chain and sprocket which will prematurely wear both. If it is bad enough, it might even cause derailment.

3. I used the technique shown in one of the Motorcylists youtube videos to put a rag in between the sprocket and chain when tightening everything up. Is this to prevent over tightening stuff? How much do I need to tighten the lock nuts? My user manual only had torque tension for the axle nut.
:tab Interesting. I have never heard of that technique. The issue is the geometry between the center lines of the sprockets and the hinge point of the swing arm. Because the swing arm hinge is behind the front sprocket, the distance from the center line of the front sprocket to the center line of the rear does not stay constant. If you don't have a straight line through the center of all three points, front sprocket, swing arm hinge, and rear sprocket, then the distance decreases and you get more slack. The straight line configuration will have the longest distance. So if you adjust the chain while there is an angle, like say with the bike sitting on the side stand where most bikes have the rear shock extended since the bike is not loaded, when the swing arm does make a straight line, the chain will be too tight. I suspect that putting the rag in there is an attempt to compensate for this while letting you adjust without compressing the rear suspension until the swing arm makes a straight line.

4. Is it normal that my chain slack varies from 30mm all the way to 45mm? Spec is between 25-35.
:tab Erring on the side of loose is better than tight. You just don't want it so loose you risk derailment. But also, you don't want the chain flopping all over the place because it can setup some nasty vibes. If you have the axle as far back as you can go with the adjusters and you still have a lot of excess slack, it is time for a new chain.

5. Once on the center stand, I put it in first gear, and the chain seemed to have varying degrees of noticeable tightness. It even rattled whenever it reached the tighter spots (I assume). This appeared to be gone after some cycles though.
:tab There is a difference between "tight" as in the position of the rear axle relative to the front sprocket, and "tight" as in the links don't pivot well on their common pins, causing you to see kinks in the chain as it moves. The kinks can be an indicator that the chain is dirty and in need of cleaning and lubrication. If you have an O-Ring chain, rattling is usually an indicator that your O-Rings are gone, which is bad, because they hold the grease inside the chain to lubricate the pins holding the links together. If the bike is not running, tap the side of the chain. If you here a lot of rattling, it might be time for a new chain.

6. How straight does the chain need to be? I used the Motion Pro's tool to check chain alignment, and it looks pretty straight, but does it matter if its slightly to one side or the other?
:tab You want it as close as possible, but it does not have to be absolutely perfect. This is why the sprockets have angles on each side of the teeth. Hold it flat and look at it edge on, and you will see these angles. That allows for slight error. Alignment is also about having the wheels in line with each other, not just preventing chain wear. A crooked rear wheel can make the bike track funny and also wear the back tire out faster.
 

Ocho

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Thanks for the feedback, guys. I only have around 4.3k miles on the bike and chain and has mostly been garaged. I’m not sure if got the wrong type of chain lube or what but I try to lube it every 500 miles. I haven’t done a great job cleaning the chain, though.

Went to CznBob and talked to him about the adjustment and it seemed that the setup was done well. I forgot to show him the chain running, though.

Does the video of the chain running look highly unusual? I usually only spray lube on the O ring sides, not much the middle.
 
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Fm 1681, Stockdale.
Thanks for the feedback, guys. I only have around 4.3k miles on the bike and chain and has mostly been garaged. I’m not sure if got the wrong type of chain lube or what but I try to lube it every 500 miles. I haven’t done a great job cleaning the chain, though.

Went to CznBob and talked to him about the adjustment and it seemed that the setup was done well. I forgot to show him the chain running, though.

Does the video of the chain running look highly unusual? I usually only spray lube on the O ring sides, not much the middle.
Spray both sides and the middle

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Tourmeister

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Video of bike running looked normal to me. Chains will always bounce around a bit.

That Motion Pro tool is WAY more high tech than anything I've ever done! I just make sure my adjusters are at the same point and go.

Keeping a chain clean is probably the biggest factor in chain life. Excess lube holds dirt. Dirt creates friction. Friction is bad ;-) If a chain gets wet often and is allowed to rust, rust is bad. Rust creates friction. Friction is bad ;-) Dirt and or rust will wear down the O-ring, sometimes VERY quickly. It is the grease in the O-rings that really does the major lifting. At best, external lubrication keeps the O-rings from dry rotting or generating too much friction between the plates and rubber, thus wearing down the rubber. The O-rings are the weak link because they are soft and wear easily.

If you lube the chain, be sure to wipe it down to remove excess lube. Don't leave it all sloppy. DO NOT hold a rag on the chain while the bike is running and in gear!! There are plenty of gross pics and videos on the web to explain why. Chains, fingers, and sprockets don't mix well. If you have a center stand, simply rotate the tire by hand and rub the chain with a dry clean rag (that you don't care about).

There are some lubes, teflon sprays I think, that dry fairly quickly and are not tacky. These are good because they don't hold dirt. Chain wax is a nightmare. It makes a HUGE mess and will hold every bit of dirt that ever gets near it.
 

Tourmeister

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I lean across the seat from the right side to compress the suspension until the swing arm is straight, then check free play. If you try this with a street bike, be careful, they are heavier than most dirt bikes and you might pull it over onto you :eek2: I guess if your bike has a center stand, you could use a ratchet style tie down strap to crank the swing arm up until it is straight, then adjust and check.
 

mitchntx

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I've never done anything more than adjust evenly and tighten the axle.
Never had an issue.
Still use the three finger dirt bike method.
A quick rule of thumb is that if you pull up on the chain on top of the swingarm and the chain just clears the upper chain guard at max stretch, yer good to go.
Bike has to be in neutral, though.
 
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Chain threads,,,break-in threads,,,oil threads,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
 
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