Chain Won't Maintain Proper Tension. Diagnosis?

[25knots]

Hey guys.  The last four or five months I've had to re-tension my chain three times... it keeps loosening up on its own. 

Any thoughts about why this could be.  The rear wheel sprocket looks fine so I'm wondering if there might be wear on small drive sprocket that connects the chain to the transmission.  I haven't looked at it yet, but is this a possibility?  The bike has over 26000 miles on it, so its its pretty broke in. 

Thanks in advance.

[adidasguy]

How are you tightening it? How tight are you making it? Too tight will wear it out and it will loosen up again.
Are you oiling the chain?
Time for a new chain? How many miles on it?

[fetor56]

At 26k mls i would be thinking about a new chain & sprockets,something descent.

[25knots]

The chain has been oiled every 400, tensioned to 20-30mm of play, as per specs.  I bought it at 15000, however, so who knows what was going on before that.

I don't know if I mentioned it before, but the rear sprocket looks fine, which makes me think the chain is also okay.

[adidasguy]

When did this problem start?
Are you adjusting the chain on the center stand  or the side stand? (It should be on the side stand.)

[fetor56]

On the furtherest part of the rear sprocket try to pull the chain backwards from it.My chain/sprockets are pretty new & don't have any chain slack when i pull at the chain.
See how much movement u have.

BTW...as per the Haynes manual i adjust the chain on the centre stand......personal preference though.

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[adidasguy]

I go by the owner's manual. Either works as long as you do it correctly.

Drive Chain Adjustment
Inspect the drive chain slack
before each use of the motorcycle.
Place the motorcycle on the
side stand. The drive chain
should be adjusted for 20 – 30
mm (0.8 – 1.2 in) of slack, as
shown.

[MarkB]

An o-ring chain typically will need very little or no adjustment over most of its life.  As it reaches the end of its useful life it will wear (effectively stretching) increasingly fast requiring frequent adjustment.  You need to replace the chain and sprockets.  26k miles is about when you'd expect this though it can vary significantly due to operating conditions and maintenance.

[25knots]

Thanks for all the advice guys.  I haven't looked into to what replacing chain and both sprockets requires, but give me your opinion: easy enough for a shade tree mechanic to get by himself... or should I call up my friendly mechanic?

[MarkB]

There's a FAQ article here on replacing the sprockets:  http://gstwins.com/gsboard/index.php?topic=32013.0
I'd want to know the torque specs on the rear sprocket bolts and would use a torque wrench on this job.

It's a FAQ for a different bike, but here's a good article on replacing the chain:  http://faq.ninja250.org/wiki/How_do_I_replace_the_chain%3F
I use a clip type master link as described near the bottom of the article which requires less special tooling, but I recognize that some people don't like that approach for the reasons stated in the article.

[25knots]

There's a FAQ article here on replacing the sprockets:  http://gstwins.com/gsboard/index.php?topic=32013.0
I'd want to know the torque specs on the rear sprocket bolts and would use a torque wrench on this job.

It's a FAQ for a different bike, but here's a good article on replacing the chain:  http://faq.ninja250.org/wiki/How_do_I_replace_the_chain%3F
I use a clip type master link as described near the bottom of the article which requires less special tooling, but I recognize that some people don't like that approach for the reasons stated in the article.

That FAQ article is perfect.  I'll let you guys know how it turns out.

[Blueknyt]

the chains are pretty robust for the amount of hp our bikes produce.   something you might want to look at is swingarm bushings, wheel and sproket carrier bearings, the backing plates behind the adjustment nuts on end of swimarm, make sure the plates arnt buckling. and while up on centerstand, slowly roll the rear wheel watching the chain for tight and loose spots.  you could adjust on a tight spot but still have loose elsewhere, same thing with sproket runout.

[25knots]

On the furtherest part of the rear sprocket try to pull the chain backwards from it.My chain/sprockets are pretty new & don't have any chain slack when i pull at the chain.
See how much movement u have.

BTW...as per the Haynes manual i adjust the chain on the centre stand......personal preference though.

Addidas,
My chain definitely has some slack when pulled from the rear of the sprocket so I'm thinking new chain and front and rear sprockets.  Do you, or anyone else, have suggestions on replacement parts that have worked well in your experiences.

Thanks again for the continued help guys and gals.

[Golly]

Ive noticed that I set the chain slack 25/30mm on the centre stand but then when I sit on the bike and my weight is added 125kg the chain tightens under swingarm load to about 5 mm play....is this normal...should I set the chain tension on the side stand then as its under semi load then with weight of the bike ?

Sent from my GT-I9210T using Tapatalk

[adidasguy]

The chain will get tighter if adjusted on the center stand and you then sit on the bike.

The owners manual says to check the chain on the side stand.

[Joolstacho]

Normal Golly. That's why you adjust the chain on the sidestand not the centrestand. Because the swingarm pivot is not concentric with the countershaft sprocket, the chain tightens when the bike has some weight on it. I also do a double check by sitting on the bike, and reaching down to feel the play in the chain with my weight on it.

[Golly]

I love this place... will adjust when I get back home.