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05 YZ 250 rear shock question

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Mar 12, 2001
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#1
When I went to ride yesterday, it seemed like my seat was sitting lower than usual. I checked the linkage and swingarm, all seem to be moving correctly.

When the bike is sitting on the ground, supporting it's own weight on the suspension, I can lift up the rear of the bike about 1" before it stops. When I let go, the bike sinks back down about an inch.

The only thing I've done to my rear shock (months and many rides ago) was put on a stiffer spring because I was too heavy for the stock spring.

So ruling out the bearings and linkage, I am thinking possibly my rear shock has a problem. Is it possible I lost some of the gas out of the shock? The shock itself looks normal and it's not leaking any oil. I have no idea how to check the pressure in the resevoir, could I use a simple air check guage you would use on your tires? What PSI should I have?

I have a buddies RM 250 in my garage, and when I weigh down his rear suspension, it goes all the way back up to where I can't lift it up like I can lift mine about 1".

If there are any stock 05 YZ250 owners out there, could you please measure from the axle nut straight up to the rear fender and let me know the measurement?

Thanks all.
 

BSWIFT

Sponsoring Member<BR>Club Moderator
N. Texas SP
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#2
You need to measure your static sag and race sag numbers. The static sag is what you have discribed (weight of the bike only). Your heavier spring may have lost some of it's unsprung tension, but that is only a guess. In the suspension forum or on the MX-Tech website, you'll find the proceedure for measuring and adjusting the sag numbers. Quite simple but you'll need some help getting the measurements because you'll need to be sitting on the bike to get your race sag measurement. After you have the numbers, you adjust the preload to attain the proper race sag. It is likely that some additional adjustments to rebound and compression may be needed but not much.
 
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#4
Thanks BSWIFT, I will definitely do some more reading and follow your suggestions.
 

BSWIFT

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N. Texas SP
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#5
Your welcome, I'm no expert at all. I call MX-Tech when I need help. I've had them do two suspensions for me and they do great work. There website helps a bunch for the quick questions. Best money I've ever spent on my bikes is suspension work. Properly setup and tuned to you, your bike will perform better and make you much more confident, improving your skills and the grin factor.
 
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#6
I had my forks revalved, resprung, and setup for my weight by mx tech. I really notice a big difference in how my front end sticks in just about any conditions.

I had this done early in the year and it took quite awhile to get my forks back from them, so I am hesitant to send off my rear shock during riding season.

I am going to work on the bike today (hopefully my hellfire lights get here today so I can test tonight). :)
 
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#7
I removed the rear shock, as the rear end was even lower and stiffer today. It's actually the linkage/swingarm bearings that are muffed. :(

I am removing the swingarm now. Assuming I get everything apart, will I need any special tools to take the old bearings/bushings out and put the new ones in?

Thanks again.
 
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#8
Once I removed the linkage from the swingarm, the swingarm moves super easy, so all I am looking at now is placing the lower linkage bearings. I think I will replace everything since it's all apart, and the pivot bolt isn't seized too bad (at least it moves).
 

IndyMX

Crash Test Dummy
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#9
I got a section of threaded rod. I think it might have been 5/16". That and a couple of nuts, heavy spacers and sockets.. I used that setup to drive the bearings out of my swingarm & linkage. With a bit of heat, some pressure from the nuts, and copious amounts of adult language, it came apart fairly easily.
 
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#10
Well, I got everything out of my linkage except the old bearing housings. The bearings were completely rusted and fell apart with one whack of a hammer and socket. The housings will NOT budge.

So, I bought some PB blaster and have it soaking overnight. I will try again tomorrow, and add some heat if necessary.

Can I push both bearing housings out one way? Or does each bearing housing need to come out oppositely?

I like the idea of using a threaded rod, but I am thinking about using a socket, piece of 2x4 wood with a hole drilled out (so the old housings have somewhere to go) and a vise to force things along.

As God as my witness ;) , the next new bike I buy will be stripped down before the first ride and greased up. I had planned to with my 05, but it's 07 now and I never got around to it. Before I slap everything back together, I am going to look at the steering stem bearings too (yup, never did that since I bought it either).
 

IndyMX

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#11
The vise & wood block thing may work too.. I did something like that until I broke my vise...

It would be a good idea to invest in a tube of anti seize compound.
 
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#12
Thanks. My vise is pretty heavy duty, hopefully the penetrating fluid and some heat will ease the job a bit.