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Loose chain needs tightening (help?)

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I have a 15 YZ125. I'm doing some maintenance and now it's time to tighten the chain. I did not attempt to tighten the chain yet because I am missing my 32mm (1 1/4") socket for the axel nut to loosen the wheel. Now here is the problem. My 1/2 wrench fits on the chain adjuster lock nut but nothing fits on the chain adjuster bolt. The 10mm (3/8") is too small and the 11mm (7/16") is slightly too big. My bike is stock if that helps. Is this normal? If I loosen the chain adjuster lock nut, will the chain adjuster bolt become easily adjustable without heavy reliance on a perfect fitting tool? 

Help please. I'm kind of confused.

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Get the correct tools. You can not convert standard to metric they are different. The chain adjusters are 10mm and 12mm. 3/8 is 9.5mm that is why it is too small. 1/2 is 12.7mm might work but you will end up rounding the nut. Also the rear axle is not 32mm it is 27mm I believe but double check.

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Yup, dump the SAE tools in the trash can, there are no SAE bolts or nuts on a modern Japanese or European motorcycle. And yes, the rear axle nut is probably 27 mm as that seems to be the constant size for every dirt bike I've worked on in recent memory (street bikes have been 32 mm though).

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On a related subject, when you do get ready to adjust your chain, go ahead and take a few minutes and remove the adjusting nuts (12mm) and bolts (10mm), and coat the threads with an anti-seize compound, or a good synthetic waterproof grease.  Make sure your axle spacer, wheel bearings, swing arm and axle blocks are free from grit and debris.  You can coat the axle shaft with a very light film of grease if you think it will stay in place for a long period of time.  Mine is removed fairly regularly for chain, tire and sprocket maintenance, and sometimes I'll just spray the shaft with WD-40 or some other lubricant.

As OLHILLBILLY and mikedabike mentioned above, the correct size will save you from some misery later on.  Also, go ahead a buy a quality set of wrenches, not some cheesy corner store stuff that may slip and start the rounded off process.  If you already have damage to the nuts and bolts, you can buy  6-point instead of 12-point wrenches for a better grip.

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4 hours ago, OLHILLBILLY said:

Yup, dump the SAE tools in the trash can, there are no SAE bolts or nuts on a modern Japanese or European motorcycle. And yes, the rear axle nut is probably 27 mm as that seems to be the constant size for every dirt bike I've worked on in recent memory (street bikes have been 32 mm though).

Pretty good chart here if you need it in a pinch.

http://extension.missouri.edu/webster/documents/Ag-edge/Standard-MetricWrenchChart.pdf

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Yup, dump the SAE tools in the trash can, there are no SAE bolts or nuts on a modern Japanese or European motorcycle. And yes, the rear axle nut is probably 27 mm as that seems to be the constant size for every dirt bike I've worked on in recent memory (street bikes have been 32 mm though).


My 2008 Kawasaki KX 250F uses a 32mm.

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The larger bolts like the axle nut, you can get away with using the sae socket in a pinch. The .009" difference between a M32 vs 1.250" isn't going to matter. Using a 1/2 on a M12 (.500 vs .47244") is going to round off the corners of the nut the 1st time you snug it.

 

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5 hours ago, Zurich said:

 


My 2008 Kawasaki KX 250F uses a 32mm.

 

Yes, you're right. I got home and looked at the socket i use for the street bikes and it's a 36 mm, not the 32 I was thinking it was. Can't remember what size the one on my '09 KX250F was, but probably 32 too. My YZ, and older WR2502F, the KDX, and probably my old XR400 were all 27 mm. :thumbsup:

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41 minutes ago, Smoking 2's said:

Not to tight I hope! You can wear a chain out in a day doing that!

 

On 7/26/2017 at 0:12 PM, yz125scrub said:

got the correct tools and successfully tightened the chain. Thanks for the help. 

You can also put undo stress on the output shaft and carrier bearing. And premature wear out chain and sprockets. A 125 can have crack the case real easy also. 

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16 minutes ago, P84ONE said:

 

You can also put undo stress on the output shaft and carrier bearing. And premature wear out chain and sprockets. A 125 can have crack the case real easy also. 

Possibly ruin a trans bearing/gears pretty quick too! Never done it but seems possible! 

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