rm 125/ rm 250 shock fitment question. help please

dbrunski125
Edited Date/Time 12/11/2015 2:14pm
I have an 04 rm 125. It has a showa shock with a 16mm shock shaft. A friend of mine is selling his 06 rm 250 and has been kind enough to give me his 06 rm 250 shock. It's my understanding that the shock has better internals and has an 18mm shock shaft. Since this is a free upgrade I want to jump all over this opportunity. I've been told that both shocks should be interchangeable and there won't be any fitment issues. Would anyone be able to verify this for me. Yes I know that the valving will me different. I will be getting the shock completely rebuilt and revalved.

Thanks
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mxtech1
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mxtech1 12/10/2015 2:02pm
12/10/2015 2:02pm
If your friend was already kind enough to give it to you why do we need to verify your fitment?

I wouldn't consider it an upgrade. Your 125 shock is designed with a smaller shock shaft to help keep the weight down and make it more responsive to a lighter bike. As are the valve stacks and spring.

Say you go and put that 250 shock on, how do you know which spring and valving to run? do you think a shock tuner is going to have a custom valve stack for that "250 to 125" swap? No, he won't. You'll spend more time and money trying to dial that 250 shock in than if you just focus on what you already have

Have your 125 shock valved and sprung and ride on.
dbrunski125 12/10/2015 2:06pm
12/10/2015 2:06pm
mxtech1 wrote:
If your friend was already kind enough to give it to you why do we need to verify your fitment? I wouldn't consider it an upgrade...
If your friend was already kind enough to give it to you why do we need to verify your fitment?

I wouldn't consider it an upgrade. Your 125 shock is designed with a smaller shock shaft to help keep the weight down and make it more responsive to a lighter bike. As are the valve stacks and spring.

Say you go and put that 250 shock on, how do you know which spring and valving to run? do you think a shock tuner is going to have a custom valve stack for that "250 to 125" swap? No, he won't. You'll spend more time and money trying to dial that 250 shock in than if you just focus on what you already have

Have your 125 shock valved and sprung and ride on.
2005 and up rm 125 shock has an 18mm shock shaft. Mb1 suspension told me would be no problem pulling apart the valve stack and re doing it for an rm 125. His bike is in storage. Won't have his shock for few months. Which is why I'm asking now.

Said I can have his forks too. Which feature better internals. And again mb1 said changing valving stack wouldn't be an issue....
Slosh 112
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Slosh 112 12/10/2015 2:10pm
12/10/2015 2:10pm Edited Date/Time 12/10/2015 2:10pm
My 08 RM125 has an 18mm shock shaft... I know because I rebuilt the whole thing from the clevis up, Had the shaft re-chromed, definitely 18mm.
Bruce372
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Bruce372 12/11/2015 1:07pm
12/11/2015 1:07pm
how much do you weight? the 2006 rm250 shock was pretty good, so you can run it as is. it will fit.

i have a 2005 RM125 shock on my 2004, it has the 18mm shaft and i run a 2006 RM250 valve stack.

by rights, the 18mm shaft will push more oil through the comp adjuster and make it more responsive to clicks...but when valved right, both shocks are really good.

If you really want to upgrade it, maybe get the SKF seal head and the mx-tech low friction piston band.

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dbrunski125 12/11/2015 2:14pm
12/11/2015 2:14pm
Bruce372 wrote:
how much do you weight? the 2006 rm250 shock was pretty good, so you can run it as is. it will fit. i have a 2005...
how much do you weight? the 2006 rm250 shock was pretty good, so you can run it as is. it will fit.

i have a 2005 RM125 shock on my 2004, it has the 18mm shaft and i run a 2006 RM250 valve stack.

by rights, the 18mm shaft will push more oil through the comp adjuster and make it more responsive to clicks...but when valved right, both shocks are really good.

If you really want to upgrade it, maybe get the SKF seal head and the mx-tech low friction piston band.
I weigh 160 lbs without great. I'd be using a 4.7 rear spring. That's good to know shock fits fine. Only reason I'm doing this is because shock is for free. Mb1 said could revalve the stack fine for a 125 do yea I didn't expect and issues that way. Thanks for the help

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