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2002 YZ250 Brutal on Washboard/Sharp Edges

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I have a 2002 YZ250 that I use for trails and hare scrambles. I've had a couple of different garage suspension guys go through it over the years and, overall, it's pretty good, but find the front is really hard on my wrists and arms (feels like pounding my palms onto brick walls as hard as I can) on "washboard" caused by rain ruts, and is also hard and causes head shake on square edged acceleration bumps. Turning the clickers out (currently at 5 clicks compression, 2 clicks rebound) makes the front more vague and doesn't seem to alleviate the problems. The "washboard" is something I only encounter at one trail I ride, but I'm suspecting what causes harshness there is also responsible for causing my front to deflect off of roots while racing; getting tired of my head flying straight for the trees.

 

Have gone back to the current suspension guy with this and he responded with suggestions for binding (checking lower triple clamp tightness, fork binding due to axle alignment, oiling the shafts, etc) and taking out rebound damping, then clammed up when I mentioned I had tried the binding things and told him my clicker setting. Probably thinks I'm going to try and pry money out of him, but I've had this issue since I first got the bike and had the suspension serviced. The first guy was able to get a little out when I asked him, but he went away and am not sure what he did.

 

I've done only a little bit of internet research on this. That which I've done was making me wonder if this was a high speed damping issue, and that Japanese MXers have this because of the piston design restricting flow at high speed. One thing I did manage to do was set up a GoPro to watch the front on some trails, but I don't know enough to interpret what I'm seeing, although it appears the forks ride in a reasonable range and don't pack over the "washboard".

 

Thoughts?

 

Thanks!

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75% of the time in these cases I find there's an incorrect spring rate being used or not enough Comp damping overall. And in some cases both issues combine. Of course occasionally there's too much damping for technical single track riding however of there's been a definite reduction in Ls damping that makes me assume what I said first.

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So, if I follow, I need to go back to that trail and try dialing in some compression damping, and see what happens?

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6'2"

210-212, depending on the time of day

"Eh" C class rider.

Hare Scrambles/Single track on Georgia woods and red clay.

 

If we're getting technical: I believe the forks have the stock springs, and the shock spring rate was increased. Don't know the rate, but the number on it is 892.0056.0.

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I recommend

.45kg

5.6kg springs

There's no way stock front springs are adequate especially if your running an oversize tank

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I'm not familiar with fork anatomy, yet. Do both of those go in the front?

 

 

I run a stock tank for now, but I did move the bars forward a good bit. And I wouldn't be surprised at the springs being too little; first garage suspension guy said my springs were borderline and I think overcompensated with damping, but I was 190-195lbs at the time. 

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Front springs are the .45kg

Rear spring is 5.6kg

Those springs combine with a basic revalve front and rear will solve your problems

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Ah! Thanks! I'll see if I can find someone to do this.

 

What are stock 2002 YZ250 fork springs, if you know?

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I've only used locals so far, quad and bike. Most recent guy is practically down the road, but its a side job and has a couple of young kids, so he's less available.

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Stock '02 YZ250 springs are .43 front and 4.8 rear.  Just got this from the manual for my bike.

 

I am very close to your size and weight and am using .46 and 5.4 springs.

 

I have an oversize tank and use the bike exclusively for trail riding, mostly single track.  I've been revalving it myself.

 

If I was racing, I might want to go a little stiffer with the springs.

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Has anyone else looked at the Race Tech web site and did their spring rate calculator?  It calculates it out for me too that the stock spring rate is sufficiently stiff for my use.  That's why I never worried about my fork spring rate.  Shock spring was a different story though.  OP, my '01 YZ250 was/is also harsh on small stuff and .ripples and as many times as I've screwed up jumps and landed HARD, I've never come close to bottoming.  For ME, I can't see how turning UP compression dampening would help me.

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The idea of stiffer damping or springs is to keep the forks up in the stroke where the lighter(softer) damping is. If the springs are too soft for your weight the forks will settle or sag and be in the stiffer damping causing harshness. The damping gets stiffer as the forks compress. Often just stiffening the damping a few clicks will help to prevent the sag but proper springs to start with is the best approach. In my experience anyhow. Good luck, the proper compromise can be a struggle to find sometimes.

Edited by YHGEORGE
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The idea of stiffer damping or springs is to keep the forks up in the stroke where the lighter(softer) damping is. If the springs are too soft for your weight the forks will settle or sag and be in the stiffer damping causing harshness. The damping gets stiffer as the forks compress. Often just stiffening the damping a few clicks will help to prevent the sag but proper springs to start with is the best approach. In my experience anyhow. Good luck, the proper compromise can be a struggle to find sometimes.

This is untrue.  Damping is NOT position sensitive.  It is speed sensitive and viscosity sensitive.  

 

What CAN chance is that there is more preload from the springs (coil and air volume) being compressed and this translates into some harshness if riding low in the stroke.  Plus it is that much easier to bottom and that is obviously hash.

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It's sitting lower on the air spring ,that's the part that may feel harsh ,the air spring ramps up fast

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I've only used locals so far, quad and bike. Most recent guy is practically down the road, but its a side job and has a couple of young kids, so he's less available.

A-1 Suspension is located in south metro Atlanta, if you need a revalve or different springs installed.

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Surprised no one mentioned it, but your clicker settings are way tight/stiff. With your clickers cranked way in like that, you have very little free bleed, which makes you feel all the little junk in your hands/wrists. Unless you're riding 5th pinned a lot?

You need to get the valving setup to where you can run your clickers in the 8-12 range, preferably 10-14.

For starters, run the clickers to 10 and 10 and ride it for a while. You may get used to the different feel of the forks. If not, then look at how much of the stroke you're using and go from there.

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Didn't realize this kept going

 

Surprised no one mentioned it, but your clicker settings are way tight/stiff. With your clickers cranked way in like that, you have very little free bleed, which makes you feel all the little junk in your hands/wrists. Unless you're riding 5th pinned a lot?
You need to get the valving setup to where you can run your clickers in the 8-12 range, preferably 10-14.
For starters, run the clickers to 10 and 10 and ride it for a while. You may get used to the different feel of the forks. If not, then look at how much of the stroke you're using and go from there.

 

I believe I listed them backwards from what's typical. My settings were 5 and 2 IN from full out, not out from full in which seems to be convention. So, with 20 clicks, that would be 15 compression and 18 rebound?

Since this, I actually set them to 14 and 18 out to see if that would have the side effect of speeding up the rebound and emulate a slightly stiffer spring, and that seemed to help a bit. Tried 13 and 17, then 13 and 18, but the former seemed to start to deflect and the latter was a little harsher than the original. Going to talk to the guy I go to about re-springing the front when I need an oil change, and go from there.

Edited by rustyATV

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