Chain slack constantly changing? Help

yz8103
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yz8103
Edited Date/Time 2/26/2019 11:43am
Hi all, I ride a 2011 sx 125 and I seem to be constantly setting the chain slack. Every time I rode it seemed to be too loose when I came back, so I replaced the chain, lubed it up and the same things happening? Am I leaving too much slack? Any advice? How much slack should I have behind the chain slide while SITTING on the bike? I currently leave about three while off the bike and I weigh about 60kgs. thanks a lot .
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yz8103
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yz8103 2/23/2019 10:38am
2/23/2019 10:38am
Here are pictures of my sprockets

brody
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brody 2/23/2019 11:05am
2/23/2019 11:05am
lube the chain
your axle may not be tight enough so the wheel slides back
1
mxgreg85
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mxgreg85 2/23/2019 12:17pm
2/23/2019 12:17pm
The most accurate way would be to remove the bottom shock bolt and pick the rear wheel up (ratchet strap around subframe to lift rear wheel helps) so that the rear axle and swingarm bolt are straight across from each other. This is the point at which your chain is most extended. Set it moderately tight at this point, reinstall the bolt, and measure the slack from a given point when you let the wheel back down. Set it to that amount of slack in the future. Wedge a small wrench in between the rear sprocket and chain when you're tightening everything so that the rear wheel stays in position and does not slide back. Make sure both sides are even with the marks on the axle blocks and swingarm. What kind of chain are you using? Any decent one should not wear that fast on a 125.
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yz8103
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yz8103 2/23/2019 12:24pm
2/23/2019 12:24pm
mxgreg85 wrote:
The most accurate way would be to remove the bottom shock bolt and pick the rear wheel up (ratchet strap around subframe to lift rear wheel...
The most accurate way would be to remove the bottom shock bolt and pick the rear wheel up (ratchet strap around subframe to lift rear wheel helps) so that the rear axle and swingarm bolt are straight across from each other. This is the point at which your chain is most extended. Set it moderately tight at this point, reinstall the bolt, and measure the slack from a given point when you let the wheel back down. Set it to that amount of slack in the future. Wedge a small wrench in between the rear sprocket and chain when you're tightening everything so that the rear wheel stays in position and does not slide back. Make sure both sides are even with the marks on the axle blocks and swingarm. What kind of chain are you using? Any decent one should not wear that fast on a 125.
DID roller I think, thanks for the help??

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HackMan162
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HackMan162 2/23/2019 12:32pm
2/23/2019 12:32pm
Your sprockets are worn out also. So will wear the chain quicker.
Keith72
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Keith72 2/23/2019 1:25pm
2/23/2019 1:25pm
mxgreg85 wrote:
The most accurate way would be to remove the bottom shock bolt and pick the rear wheel up (ratchet strap around subframe to lift rear wheel...
The most accurate way would be to remove the bottom shock bolt and pick the rear wheel up (ratchet strap around subframe to lift rear wheel helps) so that the rear axle and swingarm bolt are straight across from each other. This is the point at which your chain is most extended. Set it moderately tight at this point, reinstall the bolt, and measure the slack from a given point when you let the wheel back down. Set it to that amount of slack in the future. Wedge a small wrench in between the rear sprocket and chain when you're tightening everything so that the rear wheel stays in position and does not slide back. Make sure both sides are even with the marks on the axle blocks and swingarm. What kind of chain are you using? Any decent one should not wear that fast on a 125.
A rag between the chain and rear sprocket works well to.
Texas Built
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Texas Built 2/23/2019 10:05pm
2/23/2019 10:05pm
I know its stupid and not needed, but Motion Pro makes a tool.

Keith72
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Keith72 2/24/2019 8:50am
2/24/2019 8:50am
Are your chain adjuster bolts staying tight?
yz8103
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yz8103 2/24/2019 9:14am
2/24/2019 9:14am
HackMan162 wrote:
Your sprockets are worn out also. So will wear the chain quicker.
Both?
kb228
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kb228 2/24/2019 4:23pm
2/24/2019 4:23pm
Maintain your chain and it will probably hold better.
Keith72
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Keith72 2/24/2019 4:36pm
2/24/2019 4:36pm
Keith72 wrote:
Are your chain adjuster bolts staying tight?
yz8103 wrote:
Ya?
Do you have a pic of the adjusters you can post?
Keith72
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Keith72 2/24/2019 4:39pm
2/24/2019 4:39pm
HackMan162 wrote:
Your sprockets are worn out also. So will wear the chain quicker.
yz8103 wrote:
Both?
That front sprocket looks like it is starting to hook a little bit. Back doesn't look too bad.
Falcon
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Falcon 2/25/2019 2:47pm
2/25/2019 2:47pm
When you replace your chain, do both sprockets as well. A slightly worn sprocket will quickly stretch your chain, which will wear the other sprocket as well.

One other tip I use to make sure my wheel is aligned properly is to look at the sprocket teeth through the chain when seated behind the bike. The sprocket should be in alignment with the chain all the way up to the front sprocket. I'm a fan of the "hook a box-end wrench on a tooth of your rear sprocket and rotate the wheel backward until the chain tension snugs the axle blocks into the chain adjusters" method. Look at the alignment while you have the wrench wedged in there.

After all that, you should be able to put three fingers underneath your chain, just behind the chain slider with no further wiggle room. If you can't get three fingers in, your chain may be too tight.
layenpipe25
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layenpipe25 2/25/2019 4:00pm
2/25/2019 4:00pm
Like everyone has mentioned, make sure your chain and wheel is aligned, tight, and against the tensioners. If you bike axle blocks are beat up, try using a MIC for better alignment. If you ever rode with sprocket bolts loose, the holes could be yoked in which case you will never get proper chain tension and your hub is trash. Check the chain tension, rotate the wheel a quarter turn and check it again. Do this a few times. Do you get a different tension every time?
yz8103
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yz8103 2/26/2019 11:41am
2/26/2019 11:41am
Falcon wrote:
When you replace your chain, do both sprockets as well. A slightly worn sprocket will quickly stretch your chain, which will wear the other sprocket as...
When you replace your chain, do both sprockets as well. A slightly worn sprocket will quickly stretch your chain, which will wear the other sprocket as well.

One other tip I use to make sure my wheel is aligned properly is to look at the sprocket teeth through the chain when seated behind the bike. The sprocket should be in alignment with the chain all the way up to the front sprocket. I'm a fan of the "hook a box-end wrench on a tooth of your rear sprocket and rotate the wheel backward until the chain tension snugs the axle blocks into the chain adjusters" method. Look at the alignment while you have the wrench wedged in there.

After all that, you should be able to put three fingers underneath your chain, just behind the chain slider with no further wiggle room. If you can't get three fingers in, your chain may be too tight.
Thanks, I will replace my sprockets also.


yz8103
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yz8103 2/26/2019 11:43am
2/26/2019 11:43am
Falcon wrote:
When you replace your chain, do both sprockets as well. A slightly worn sprocket will quickly stretch your chain, which will wear the other sprocket as...
When you replace your chain, do both sprockets as well. A slightly worn sprocket will quickly stretch your chain, which will wear the other sprocket as well.

One other tip I use to make sure my wheel is aligned properly is to look at the sprocket teeth through the chain when seated behind the bike. The sprocket should be in alignment with the chain all the way up to the front sprocket. I'm a fan of the "hook a box-end wrench on a tooth of your rear sprocket and rotate the wheel backward until the chain tension snugs the axle blocks into the chain adjusters" method. Look at the alignment while you have the wrench wedged in there.

After all that, you should be able to put three fingers underneath your chain, just behind the chain slider with no further wiggle room. If you can't get three fingers in, your chain may be too tight.
Thanks, I will replace my sprockets also.
Here are photos of my adjusters.

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