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WTD: Shim Stack rec for 03 YZ250F

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Hi,

I purchased a 03 YZ250F about a month ago and have been working on the suspension. The suspension was completely stock when I got it and it was HARSH, HARSH, HARSH. So, I was wondering if any creative folks out there has come up with some valving spec's they would be willing to share.

Here is the specifics thus far..

5'9" - 180 Lbs. Inter level vet rider. Moto and trail. Todate though it's been all moto...

Shock:

I've remove qty (2) of the .22x40 washers from the high speed part of shock compression stack, I also changed the cross over from the stock setting (qty (1) x .14x34 + qty (1) .14x30) to qty 1 .29x18 to allow it to blow off a bit more. That's helped but it's still too harsh. I'm now looking to reduce it even further as it's not as complient on square edge bumps as I'd like plus it's not bottoming harsh at all on the moto track.

Fork:

Removed qty (2) of the .12x24 from the high speed part of the stack. Also removed one of the .15x22 from further down in the stack and one of the .15x18's as well. It's better but still not plush enough. Before I did this it would shake at speed in the ruff. Now it goes streight but it's still not plush enough..

If anyone has a stack they built that they liked and would share it that would be great..

Many thanks....

PT

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The shims you talk about removing are actually in the lowspeed part of the stacks. This bike needs more than just a cpl shims removed to make it work. Since some of us here make a living with our "specs" its hard to just print them up here. Your forks have CV and midvalve issues that need to be addressed also so just removing a cpl shims isn't going to help much. You are also in need of some stiffer springs.

doc

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Well, I honesently wasn't expecting a person who makes their living at tuning suspension to share their spec's. I wanted to reach out to the folks that do their own work and was hopeing to get a responce from someone who has tried some different combinations and come up with something they like. I've got a few ideas up my sleaves that I'll try and report back to the form here if I get the results I'm after. Also, the springs on the forks are stiff if anything. I could use a stiffer rear spring but the forks, in my opinion, need to go softer not harder...

PT

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You may want to investigate further when it comes to front springs. I weigh 190, had my suspension done by a reputable company. But I didn't have them change the front springs. I still had some harshness in the forks when going through braking bumps. Called the company and they suggested going from the stock .43 to a .44 spring rate. I changed them as recommended, and the difference was extremely noticeable. You would think that you need a softer spring, but not necessarily so. I think I may know why, but I'm no suspension expert so maybe someone else can explain it. Then again, it's probably been researched a thousand times already. Perhaps you should do a search......

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I have a great set-up and the knowledge needed to do the valving. however much like the shockdoc i do suspension work and have spent countless hours and money testing different settings. While I would like to help it wouldn't be fair to those out there making a living off of the their hard work and investment. Send it off and have a professional do.

Suspension work is like by heart by-pass surgery, call doctor for chest pains and send your susension to a qualified tech for revalving.

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I'm a little surprised the suspension was so harsh when you got it. You are close to the weight and application the bike was set up for. I am also 5-9 and 180 lbs. For me the stock 250f was a little soft and wallowy for moto, and just a little bit harsh in the woods.

I don't know enough to give you any recomendations. I've been using the gold valves and have had really good luck with the shock. The forks are a little more complicated. You might need slightly stiffer springs.

One things for sure, just making educated guesses on shims will lead to allot of frustration and head scratching for a long period of time. I would either pay for a re-valve, or get the gold-valves if you want to learn for yourself. Good luck :cry:

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Shockdoc knows what he's talking about. The bike probably feels like the springs are too stiff but in actuality they are soft and the bike is riding down in the stroke effectively loosing their effectiveness in the soft stuff.

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Actually, I think I found the issue. I went to one of the local suspension tuners as I wanted to cut to the chase and not play around much longer. As I described the behavior of the bike he told me "something else is wrong". He asked me to check the fork tubes for stiction. Turns out they have enough stiction in them that you have to press down on them to get them to compress with no internals in the forks. So, I'm working on the stiction issues and he's got the shock shaft and fork internals.... We'll see what comes of it. But, I got to tell you, I rode a 04 and 05 CRF250. WOW... If this doens't work well when I get it back I'm selling it and buying a honda!!!

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Mkae sure when you put everything back together that you make sure the R/S fork is not bound up on the axle.

doc

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Ok.. Got the bike back up and running. It works better. Smoother. However, I jumped on the 05 CRF250 right after riding my bike again and.. .Well, the YZ is for sale. I'm going red.

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Why not try the 05 Yamaha? It's supposed to have an equally good twin chamber fork, and you don't have to worry about the reported reliability issues.

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Shock:

I've remove qty (2) of the .22x40 washers from the high speed part of shock compression stack, I also changed the cross over from the stock setting (qty (1) x .14x34 + qty (1) .14x30) to qty 1 .29x18 to allow it to blow off a bit more. That's helped but it's still too harsh. I'm now looking to reduce it even further as it's not as complient on square edge bumps as I'd like plus it's not bottoming harsh at all on the moto track.

Let me just say that I admire anyone who's willing to experiment with their own shocks. It sucks that you can't buy the damper interals from dealers or else there'd be a lot more people with experience doing this stuff. Two questions for you:

1. Do you refill the bladder with nitrogen gas? If so where do you buy it and do you need a special adapter to get it from the bottle to the bladder?

2. Can you explain to a novice like me what a "crossover" is?

Thanks!

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I had the shock recharged at the local dealar. Typically it's $5.00. I always use 200 lbs as the amount of pressure.

A cross over is the small diameter (outer diameter or OD) shim that is really a "spacer" between the two layers of a "2 stage" or multi stage washer shim stack. If you look below - the 3rd line of dashes would be the cross over shim. The shim's above it flex around it and are able to open up a bit more before hitting the shim below it. Hope that makes sense...

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Well I just did a revalve on my 04 250f using racetech gold valves and shim settings. I learned a lot from the videos and from my understanding, just removing shims isnt going to solve your problem. If you are saying its to harsh at low speed then try replacing the shims with a lighter more flexible shim. Work on the low speed first thats where all the plushness is going to be. Make sure you get the crossover shim in there also or it wont work properly. Try to do one section of the stroke at a time until you get the propper shimming and performance you want. Also try sending them out to racetech or factory connection and get them revalved and reshimmed by a professional that knows what he is doing. Trust me you will be much happier with a professionaly set up suspension than you would with the stock honda suspension. I know I am and I did it myself with out a professionals help.

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Well, I don't want to pick a fight, but I just had them professionally done and they are still not right- not even close. Suspension is such a funny an interesting thing. It take a lot of testing. That and a knowledge of what each option does (springs, shims, fork oil, fork oil level, pistons etc..). Sigh..

P

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Ok, I've come up with a setting that works pretty darn well. There is room for improvement but the bike now tracks streight, doesn't send jolts through my spine and is much smoother and more controled. It's plush enough for the woods as well. If your a hard core supercross guy they it would be a bit soft. However, it's much better than stock!

E-mail me personally if you want the shim stack... PT564@aol.com

PT

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Hey, a couple of thumbs up and hanging in there with the experiments!!!! :cry:

A couple of things about KYB forks- they are very sensitive to worn bushings, and have bushings which wear rather quickly. The result of said bushings is a nasty case of stiction which will haunt you until the problem is corrected.

I have two 03 YZ250Fs with identical valving. One is the 155# AA kid's, the other is mine (185# Sen A) and both are used in the woods. Both have stock fork springs, I run a 5.0 shock spring. In good condition, either works very good in either woods or medium duty MX. This fall, my bushings were worn and my bike's fork worked like CRAP compared to the kid's bike. It felt stiff yet blew the stroke. New bushing time... :cry:

Also, the stock 03 YZF forks came with some weird fluid which turns into pancake syrup at cooler temps. Just getting rid of the stock fluid will make a difference.

Lastly, don't jump on the CRF bandwagon without opening both eyes REAL good. I had a 04 CRF for a short time and absolutely hated it. It does not bump start like a YZF, it often refuses to start in gear, the carb is PITA to R&R, and so on. I never did get the hang of "Honda" handling either. FWIW, you do not hear YZF guys discussing different offset triple clamps, so I may have been on to something. Also, do NOT expect to have the same troublefree valve life as your YZF, although I never owned mine long enough for that to arise. A local kid's CRF broke the cylinder skirt and saw $2000 flash before his eyes. :cry:

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PT564

Nice work! Keep working at it looks like your on the right track. :cry:

Have you heard of these guys http://www.suspensionnetwork.com/ you can post shim stack and compare. They have also excellent tutorial on how suspension works.

Since you don't mind sharing, how do you fill the shock with oil without getting air in the fluid?

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Toolie,

Here's a link to better explain oil changing.

www.motoprofessor.com

Punch buttons until you get in to the motorcycle suspension selections.

Something else, is that the KYB shocks can benefit from a small hole drilled between the seal head to the outer diameter of the seal, just below the O-ring. This little hole will allow the air to escape while you are pushing the seal head into the body.

Good luck with it!

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