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Yz muffler and overtight hex bolts :(

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Trying to get my muffler apart to repack it on my European yz125 2009 ... but 4 pesky little hex bolts stand in my way!! Looks to be a different design on the US model.

Trying to turn them just strips them. Rounded edges make them really hard to grasp with a monkey wrench. It just slips off. I'm at a loss :/ any ideas guys?



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Cut a slot across the top of the head with a hacksaw, then use a flat-blade screwdriver to unscrew the bolt.


I've had to do that twice before and it worked sweet both times.


Good luck!

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Thanks, I'll try that next time, if I'm less lucky.

I don't know what did it in the end, but they came free with the hex wrench. I used wd40 thin lube spray, hit them with a plastic hammer to loosen the lock tight and wrenched at them for an hour! Will power and bloody mindedness won Lol. Anyway you can see the results :)

Thanks for your help.





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I had the same problem about 2 weeks ago; 2 of them came loose, the other 2 were seized.


I got some PB Blaster, soaked the 2 bolts, then tapped them with a rubber mallet.


Did that at least twice (can't remember if it was more) over the course of maybe an hour or so.  Think I made a post about it.


Put Vise Grips on them and they came right out.


If the Vise Grips won't stay on the bolt when you put them perpendicular to the long axis of the bolt, attach them parallel to the long axis.  And if needed you can twist the Vise Grips with a Crescent wrench, channel locks, etc.


Good luck.


Edit:  You posted while I was typing.


Suggestion:  buy some anti-seize for them as I did.

Edited by SpunBearing

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I didn't have the Yamaha gasket seal recommended in the work shop manual to seal the end. So I improvised with some black RTV sealant that's good for 250 degrees c. Should think that'll do it! Hope so anyway.

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Glad to know I'm not the only one who had these problems :)

Thanks I'll get some of that anti seize copper compound... And some new bolts because these took quite a bashing and I like everything to be perfect :)

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I put new bolts in myself. Bought OEM from RockyMtn.

May have been able to find suitable subs for less in town, but figured by the time I called, drove around, etc. the price (time, fuel) would have been the same...but with less hassle.

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