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Rear Shock of 2014 YZ250 Heatingup/Locking Up

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Hello, recently I purchased a 2014 YZ250 two stroke and after 3 rides I experienced a problem with my rear suspension locking up. On my 2013 YZ250 I experienced the same issue and 3 other YZ250 owners I ride with have all experienced the same issue on their bikes.

 

When I go out and ride after about 5 minutes the rear suspension heats up and becomes binded. If you were to sit on the seat the rear shock does not move (not even to allow rider sag). But after about 10 minutes of allowing the suspension to cool down the rear shock frees up on its own.

 

Today I talked with both Factory Connection and Pro Action Suspension on the phone to research information on what is wrong with my rear suspension. After explaining to Pro Action the issues with my rear shock they informed me that often times the seal head and piston band will overheat and swell up. He said this causes the shock to lock up/not move but after the shock cools off the suspension moves freely again. In addition he said that this is a common problem on yamaha rear suspensions but he has fixed them in the past and never had any issues.
 

After speaking with Pro Action Suspension I called Factory Connection to further research the issue with my bike. After explaining my issue with the rear shock the Factory Connection Representative told me that in years past bikes have come from the manufacturer with shock bodies which were not true. He explained that if the shock body was not true it could cause the piston band to heat and swell up causing the shock to lock up. Also he added that sometimes the issue is caused by the oil being used in the suspension.

 

My question is has anybody else experienced this problem and what was the solution to fix the rear shock.

 

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I always drill a couple holes in the piston bands between the orings and haven't had a problem

But it is somewhat of a common problem

Never had them do it after the holes though

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same problem on my yz250 only locked up when hot :banghead:  ..I drilled 2 holes problem solved :thumbsup:

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Never heard that before, we have lots of yz's and yzf' which use the same shock and not heard of that once. The data would suggest it's something they have done to there bikes locally that's caused this based on 4 bikes to have the same issue in the same area. Maybe it's a local tuners special oil, one of them let that horrible smelly air out of the shock as a hot tuning tip. I'm sure it's not impossible but for the shear quantity of shocks that kyb produce for all manufacturers I would not think it's a concern and certainly not on a 2015 yz that uses the well proven sss.

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It happened to a friend of mine too, I relieved the piston band as well as replaced the oring in the bottom of the shockshaft to fix. It was like something was causing the rebound needle to close off. It was on a YZ250 also, stock shock. Never seen it or heard of it until this one earlier this year. Not a common problem though.

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Never heard that before, we have lots of yz's and yzf' which use the same shock and not heard of that once. The data would suggest it's something they have done to there bikes locally that's caused this based on 4 bikes to have the same issue in the same area. Maybe it's a local tuners special oil, one of them let that horrible smelly air out of the shock as a hot tuning tip. I'm sure it's not impossible but for the shear quantity of shocks that kyb produce for all manufacturers I would not think it's a concern and certainly not on a 2015 yz that uses the well proven sss.

This. I'm skeptical.

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Yami needs to have 50mm shocks in 125/250 models just as 250/450's do. My opinion of course.

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Why is it then when you buy a new band from oem kyb it has a hole already in the band then?

Given your expertise I defer to your point. But I know plenty YZ riders that ride our HS and enduro series and have never heard of a problem. The great majority are on stock susp. Is this a problem for the advanced rider only who puts a lot of heat into the shock?

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I really like the 46mm one

Marcus, what aboot the 46mm do you prefer? I've been having a good go with new style 50mm.

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The new 46mm on the husky's prior to KTM were nice, they had the same rebound adjuster/bleed as the newer 50's which I like.

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Marcus, what aboot the 46mm do you prefer? I've been having a good go with new style 50mm.

mark I think it's just how easy they are to get a good feel for , you can put almost any valving in and they work decent lol

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I've seen it happen where it even scored the shock body. Once replaced, no issue. I might lean towards the out of round theory. You also may want ot make sure the linkage and shcok bearings are in good shape. I've seen bound up bearings put such a side load on the shaft/piston that it too gouged the inside of the body

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IMO it is pressure building up behind the piston band (in most cases). Drilling a cpl bleed holes work and also the new MX-Tech metal & teflon piston bands work awesome....

 

doc 

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Sorry to be semi-off topic, but what size hole is the stock hole that was mentioned? I am working on my 2005 KX125. It has one hole centered between the two o-rings. I don't really have a way to measure the diameter. I think I will need to buy a drill bit that tiny. The replacement piston band does not have a hole, so I will need to drill one.

 

Thank you.

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