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WR450F fork saga

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Current 2007 WR450F forks: trying to make them float over rough terrain a lot better.

Currently:

- .50 springs (260lbs)

- Pro-Action standard kit: new bottom valve and shim stack

- stock mid valve/stack

- 100mm 5wt fork oil height

- c 12 out, r 14 out

The forks works well on hard hits, rolling bumps, g-outs, etc. Very controlled, great traction.

What they don't do well is successive studder/braking bumps, or rocks.

The suspension will effectively stop working, the suspension will become very stiff, and the bike will drift off line, then come back to normal afterwards.

Makes it really difficult to ride a rocky trail, cause you cannot hold a line.

Rear has 6.0 and some valve work done by ESP. To keep it up in the stroke, I've put the compression all the way in, high speed is in 1/8 past stock, and rebound is in 5 clicks in from stock.

The rear responds just like front, only it packs up much quicker and more viloently , and then it will loose it's line too.

I will address the rear issues too, but never found that to be a very difficult job.

My next step with the forks is to try stiffer springs (.55), and less rebound, but it seems like the forks get to the mid stroke and just stop responding to multiple quick hits.

I have tried Smart Performance front and rear tuning on (2) other WR's and did not have good results. Waaaaay to much stiction and deflection at any speed. So please don't give me indignant responses like "quit messing around and let Dave take care of it".

I wan't to know if anyone has PERSONAL experience with these forks, and if the issue can be solved.

So what am I comparing to?

My CRF450X Showa suspension with ASR valving and spring change.

My KX450F with KYB suspension with ASR valving and spring change.

Both 'float' over rough terrain, stay high in the stroke, and hold a line unless it's pretty nasty. Yeah, I know, better stuff, that's why it works better.

So, can the stock WR forks be made to respond well?

TIA

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The suspension will effectively stop working, the suspension will become very stiff, and the bike will drift off line, then come back to normal afterwards.

Makes it really difficult to ride a rocky trail, cause you cannot hold a line.

So...this is the most bizarre portion of the post...and the most difficult to understand.

I mean...there is nothing that I can think of, internally, to where you could cause a suspension to become stiffer by pumping it really fast over and over again.

It might be possible to pump fluid out of a cartridge faster than it can re-fill, which would cause the fork to fall down in the stroke...which may lead you to believe that it's harsh or stiff....but that's the only thing I can think off.

It's also possible that you have too much rebound and it's packing, which in turn is bringing it down on the main and air spring, making it stiffer as you roll from bump to bump. That is actually a fairly common problem.

Or....perhaps this is just related to the nature of the bump. Perhaps these bumps create a velocity and displacement that is greater than the other bumps you are hitting...and, the fork just won't blow off this amount of pressure in said amount of time. In other words, the dynamics of both the fork and shock are of such that they just can't tackle bumps of this nature.

But...the bottom line is that unless someone just so happens to have a precise background in the suspension that you have in your bike, (not likely) no one is really going to be able to precisely solve the problem without some further details on the design. In other words, you're going to need someone to put this under the microscope.

By the way, who is ASR and if you have had good success with them in the past, why not take this fork and shock to them to set-up?

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I have tried Smart Performance front and rear tuning on (2) other WR's and did not have good results. Waaaaay to much stiction and deflection at any speed. So please don't give me indignant responses like "quit messing around and let Dave take care of it".

It's not "stiction" by the way, which is static friction. Static friction is the amount of force required to initiate movement based on the friction that resides between two surfaces. This is a type of friction that locks two materials together.

You get additional static friction when the lower tube is run dry (such as after washing a bike) or when certain solvents penetrate the seals, causing them to swell. If you were to cut into the chrome of the lower tube you would also see an increase in static friction.

We don't do anything that would increase static friction.

I think your concern with our designs was the nature of our mid-valves. They are a lot more responsive than stock and could cause some deflection in certain conditions where a stock mid-valve would not.

There is certainly a subset of users that like a suspension to be very compliant. Almost silly soft, but of course, still not bottom. Factory Connection is a good example of this, and we are the exact opposite of it.

I think I have found that over the years, guys that have been riding many years with a certain type of loose suspension, (if I can call it that) can never adapt to the style of our designs. I have since learned to ask certain questions when someone inquires about our stuff to make sure that we don't have a mismatch.

But clearly, guys like you can't imagine how anyone could like our stuff, and guys that like our stuff can't imagine how you could like what you ride on.

I've mentioned before that suspension set-ups can be like a pair of jeans, and no one would ever admit that this is a one approach fits all business.

But clearly, you are also a very technically minded micro manager of a rider and there are guys that would pay good money to have someone of such on their testing payroll.

Don't give up!!! :smashpc:

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So...this is the most bizarre portion of the post...and the most difficult to understand.

I mean...there is nothing that I can think of, internally, to where you could cause a suspension to become stiffer by pumping it really fast over and over again.

It might be possible to pump fluid out of a cartridge faster than it can re-fill, which would cause the fork to fall down in the stroke...which may lead you to believe that it's harsh or stiff....but that's the only thing I can think off.

It's also possible that you have too much rebound and it's packing, which in turn is bringing it down on the main and air spring, making it stiffer as you roll from bump to bump. That is actually a fairly common problem.

Or....perhaps this is just related to the nature of the bump. Perhaps these bumps create a velocity and displacement that is greater than the other bumps you are hitting...and, the fork just won't blow off this amount of pressure in said amount of time. In other words, the dynamics of both the fork and shock are of such that they just can't tackle bumps of this nature.

But...the bottom line is that unless someone just so happens to have a precise background in the suspension that you have in your bike, (not likely) no one is really going to be able to precisely solve the problem without some further details on the design. In other words, you're going to need someone to put this under the microscope.

By the way, who is ASR and if you have had good success with them in the past, why not take this fork and shock to them to set-up?

ASR has no experience in the open bath KYB forks. He is experimenting with the Pro Action system to see if he wants to be a dealer.

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It's not "stiction" by the way, which is static friction. Static friction is the amount of force required to initiate movement based on the friction that resides between two surfaces. This is a type of friction that locks two materials together.

You get additional static friction when the lower tube is run dry (such as after washing a bike) or when certain solvents penetrate the seals, causing them to swell. If you were to cut into the chrome of the lower tube you would also see an increase in static friction.

We don't do anything that would increase static friction.

I think your concern with our designs was the nature of our mid-valves. They are a lot more responsive than stock and could cause some deflection in certain conditions where a stock mid-valve would not.

There is certainly a subset of users that like a suspension to be very compliant. Almost silly soft, but of course, still not bottom. Factory Connection is a good example of this, and we are the exact opposite of it.

I think I have found that over the years, guys that have been riding many years with a certain type of loose suspension, (if I can call it that) can never adapt to the style of our designs. I have since learned to ask certain questions when someone inquires about our stuff to make sure that we don't have a mismatch.

But clearly, guys like you can't imagine how anyone could like our stuff, and guys that like our stuff can't imagine how you could like what you ride on.

I've mentioned before that suspension set-ups can be like a pair of jeans, and no one would ever admit that this is a one approach fits all business.

But clearly, you are also a very technically minded micro manager of a rider and there are guys that would pay good money to have someone of such on their testing payroll.

Don't give up!!! :smashpc:

Dave

I've ridden several dozen different re-valves over the years, but the one's I got from you were un-rideable. Don't know why that was, if it was a mistake on my or your part regarding the setup requirements, or if it was designed for a rider of supreme caliber. All I know was I could not hold on to the bars in the rocks; they would be knocked out of my hands. I had several people ride the first and second set, with the same results. One rider said 'it feels like the forks are filled with 50lbs of air', which was a pretty astute description of the fork action. It's was not a matter of 'micro- management, or one-size-fits-all requirements.

I am friends with the person who bought my last '07, and he ended up putting on '06 YZ250 forks, cause he could not get the SP moded forks to hold a line.

Sorry, but that was my experience.

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Dave

I've ridden several dozen different re-valves over the years, but the one's I got from you were un-rideable. Don't know why that was, if it was a mistake on my or your part regarding the setup requirements, or if it was designed for a rider of supreme caliber. All I know was I could not hold on to the bars in the rocks; they would be knocked out of my hands. I had several people ride the first and second set, with the same results. One rider said 'it feels like the forks are filled with 50lbs of air', which was a pretty astute description of the fork action. It's was not a matter of 'micro- management, or one-size-fits-all requirements.

I am friends with the person who bought my last '07, and he ended up putting on '06 YZ250 forks, cause he could not get the SP moded forks to hold a line.

Sorry, but that was my experience.

Well... I can tell you exactly why that is. On most of our designs, we clamp our mid-valves...and others don't. And we do that because there is a need for this style of suspension set-up from a lot of riders. You're early list of what you wanted best fit that design specification. But I do take the blame for not understanding that need better.

And I can completely understand why this is not working for you and your friends because most likely you are all riding in a similar manner on the same terrain. Again, my fault for not reading the needs better.

That said, we have other designs...and we have built some very good rock climbing type suspensions. But often we don't know what someone wants or needs until we put them on it, and they provide some feedback.

I think you drew some conclusions between the first and second set-up that what we delivered is all that we have, and that you should not bother investing any more time with us. I can understand that too, but I can also tell you from experience that problems are not solved by walking away and playing the suspension roulette game. Hence why you are where you are.

I mean, every pro rider has a suspension guy that they latch onto, and they remain committed to that guy because they know the value of that relationship. Even if the suspension guy doesn’t know everything about everything, they at least understand each other better than a complete stranger would…and that often holds the most merit.

So I have to be open and honest with you and say that you might be searching for something that most likely isn't going to exist until you make it exist.

By the way, if ASR is Allen Shaffer Racing, now Dual Sport Armory, you might be interested to know that a lot of what they installed was developed by us. So your other two bikes most likely have our technology in there...if this is the case. That said, Allen was very good and very smart (and still is) about tweaking our designs to meet the specific needs of each customer.

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Current 2007 WR450F forks: trying to make them float over rough terrain a lot better.

Currently:

- .50 springs (260lbs)

- Pro-Action standard kit: new bottom valve and shim stack

- stock mid valve/stack

- 100mm 5wt fork oil height

- c 12 out, r 14 out

The forks works well on hard hits, rolling bumps, g-outs, etc. Very controlled, great traction.

What they don't do well is successive studder/braking bumps, or rocks.

The suspension will effectively stop working, the suspension will become very stiff, and the bike will drift off line, then come back to normal afterwards.

Makes it really difficult to ride a rocky trail, cause you cannot hold a line.

Rear has 6.0 and some valve work done by ESP. To keep it up in the stroke, I've put the compression all the way in, high speed is in 1/8 past stock, and rebound is in 5 clicks in from stock.

The rear responds just like front, only it packs up much quicker and more viloently , and then it will loose it's line too.

I will address the rear issues too, but never found that to be a very difficult job.

My next step with the forks is to try stiffer springs (.55), and less rebound, but it seems like the forks get to the mid stroke and just stop responding to multiple quick hits.

I have tried Smart Performance front and rear tuning on (2) other WR's and did not have good results. Waaaaay to much stiction and deflection at any speed. So please don't give me indignant responses like "quit messing around and let Dave take care of it".

I wan't to know if anyone has PERSONAL experience with these forks, and if the issue can be solved.

So what am I comparing to?

My CRF450X Showa suspension with ASR valving and spring change.

My KX450F with KYB suspension with ASR valving and spring change.

Both 'float' over rough terrain, stay high in the stroke, and hold a line unless it's pretty nasty. Yeah, I know, better stuff, that's why it works better.

So, can the stock WR forks be made to respond well?

TIA

One thing I notice is your spring rate seems soft. I'm 190lbs or less and run 0.48 springs otherwise I find the WR forks sit too low in the stroke.

I personally love SPI suspension on my WR, but I really like MX orientated suspension even in the woods.

I did have the exact problem you are describing on long braking bump descents when I first setup my SPI. I found it was a sag issue, running a little more sag cured the issue.

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One thing I notice is your spring rate seems soft. I'm 190lbs or less and run 0.48 springs otherwise I find the WR forks sit too low in the stroke.

I personally love SPI suspension on my WR, but I really like MX orientated suspension even in the woods.

I did have the exact problem you are describing on long braking bump descents when I first setup my SPI. I found it was a sag issue, running a little more sag cured the issue.

I agree with you about the springs, but everyone I talk to says .52 is the highest I should go with. Makes no sense to me....the race tech calc says .55, and the MX tech calc says .565............

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There is certainly a subset of users that like a suspension to be very compliant. Almost silly soft, but of course, still not bottom. Factory Connection is a good example of this, and we are the exact opposite of it.

I count myself a member of that group. Not sure if that group is a "subset" though. It might depend on where you live and what terrain you ride.

I agree with you about the springs, but everyone I talk to says .52 is the highest I should go with. Makes no sense to me....the race tech calc says .55, and the MX tech calc says .565............

The stock WR fork should be very compiant on rocks. I'd start with the 55's. The race tech spring calculator has been accurate for me.

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I count myself a member of that group. Not sure if that group is a "subset" though. It might depend on where you live and what terrain you ride.

The stock WR fork should be very compiant on rocks. I'd start with the 55's. The race tech spring calculator has been accurate for me.

The stock forks are useless. They bottom, they pack, they ride low.....they will not do for me. I've put in .52 in the stock forks, and the stock damping cannot handle it.....it becomes a pogo stick.

Yeah, but nobody makes .55 for that fork.........that I can find.

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Yeah, but nobody makes .55 for that fork.........that I can find.

have you had a look at the springs if and how much you can shorten them?

eg the 0.52 spring has 20 active coils, cut one, then you will have a 0.55 spring.

but the spring travel must not be less than the fork travel plus preload! the KYB springs usually don't allow big changes

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have you had a look at the springs if and how much you can shorten them?

eg the 0.52 spring has 20 active coils, cut one, then you will have a 0.55 spring.

but the spring travel must not be less than the fork travel plus preload! the KYB springs usually don't allow big changes

Yeah, I've heard of this technique before.

What is that ratio you are using?

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I had Smart Performance do my 08 WR450 and love it.

Some people you just can't please.

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Yeah, I've heard of this technique before.

What is that ratio you are using?

Spring constant. try this calculator:

http://www.pontiacracing.net/js_coil_spring_rate.htm

Regarding my previous comment on the stock forks. For a 165 lb. individual the stock fork is plush. So by weight scaling the spring and valving, the same should be achievable for you.

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Some people you just can't please.
..and some people feel the need to insult....

I dont think its an insult...do you please every customer with your business?

If you are un-please able, then its the truth nothing more...

I personally love SPI suspension on my WR
I had Smart Performance do my 08 WR450 and love it.

Me too :smashpc:

By the way, if ASR is Allen Shaffer Racing, now Dual Sport Armory, you might be interested to know that a lot of what they installed was developed by us. So your other two bikes most likely have our technology in there...if this is the case. That said, Allen was very good and very smart (and still is) about tweaking our designs to meet the specific needs of each customer.

Dave Im pretty sure Mr. K is referring to ASR as Agent Smith Racing

every pro rider has a suspension guy that they latch onto, and they remain committed to that guy because they know the value of that relationship. Even if the suspension guy doesn’t know everything about everything, they at least understand each other better than a complete stranger would…and that often holds the most merit.

So I have to be open and honest with you and say that you might be searching for something that most likely isn't going to exist until you make it exist.

Well said Dave!

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I wasn't trying to insult anyone just stating a fact.

Some people you just can't make happy no matter what you do.

I took my WR to a hare scramble track to see how the new SP boingers worked. The track was a nasty root and rocked filled hellhole that had never been groomed. I liked it, the bike soaked up all the nasty stuff and I noticed the bike steered much better.

Then I took it to an MX track and had a pisser there. I hit all the jumps and bottomed it but not the big clank I would have gotten from the stock bike. Bike was awesome in the braking bumps.

I haven't had that much fun in years. The stock WR would have killed me to death.

I'm going to have SP do my WR250.

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Yeah, I've heard of this technique before.

What is that ratio you are using?

simple rule of three.

0.55/0.52 = 1.0577 (or 5.8%)

20/1.0577 = 18.9

then add the gaps between the coils, thats the spring travel.

eg 20 active coils x 16mm = 320mm plus 2 x 5mm at each end = 330mm spring travel. now subtract the preload of eg 6mm, results in 324mm.

if you cut one active coil (16mm), you will get 308mm travel, means when your fork has 300mm stroke, the spring is still long enough to prevent coil bind.

just an example....

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you could get .55kg springs. i know a company that will make them. however, it seems if you are using the pro-action setup, the mid valve needs to be addressed. .52kgs are a pretty stout spring, with an appropriate mid configuration, i'd bet that would solve some of the issues with the forks. we basically make those forks function as the earlier cartridge style kyb's. they can work well. we've got a guy who's running them on a motocross track, and it's his enduro bike. lol.

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you could get .55kg springs. i know a company that will make them. however, it seems if you are using the pro-action setup, the mid valve needs to be addressed. .52kgs are a pretty stout spring, with an appropriate mid configuration, i'd bet that would solve some of the issues with the forks. we basically make those forks function as the earlier cartridge style kyb's. they can work well. we've got a guy who's running them on a motocross track, and it's his enduro bike. lol.

Yeah, MX tuning is so much easier with these forks.

I just bought a pair of 2008 YZ250 forks for $300 bucks, and am shipping it and the shock to Factory Connection.

I'm getting busy at work, and don't have time to do suspension experiments and go riding....so I'm paying someone to do it for me. Again.

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