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  #1  
Old 01-04-2005, 08:00 AM
Ranger_450F's Avatar
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Default 05 KAYABA forks

     

Anyone know where to get springs for the 05. MX TECH says they have 05 springs for the YZ250 but don't show them for the YZ450. and when you try to access you get an error.

Second: Do I have this right; you fill the forks by volume not by Height anymore?

Third: Is the stock fork oil crap like past years?

Fourth: Does the new fork require any special fork oil for the new design?

This is what I'm thinking of doing if it's overkill let me know. I will run the stock fork oil the same amount of time as I run Yamalube in the motor. Then after she's all broken in "Motor" change over to mobil 1 and switch to the good fork oil. I put in Silkolene 5wt in the 426 and it felt good.

Thanks
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  #2  
Old 01-04-2005, 08:23 AM
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Default Re: 05 KAYABA forks

I know for sure the stock fork cap is different. I want to add 8cc of fork oil to them (recommended by several riders) but I dont have a tool big enough to get the new fork caps off!

I am taking the bike to work with me one day soon and have one of my techs remove it.

I did find this info and it is confusing to say the least. My owners manual doesn't tell me anything.

From RaceTech:

Must have tools TFCW 49, TFCT 35. Spring Preload Washers must go on the bottom of the spring. Inner Chamber oil level is 150mm. Bleed inner chamber then bottom the damping rod with the cartridge laying on its side with the bleed hole facing up.


I bet the guys on here with SHowa suspension could help us out since these are basically Showa clones.
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  #3  
Old 01-04-2005, 08:30 AM
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Default Re: 05 KAYABA forks

I would certainly think that the 250 springs would fit in the 450 without issue....although I am not certain on that.
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  #4  
Old 01-04-2005, 09:14 AM
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Default Re: 05 KAYABA forks

Quote:
Originally Posted by MotoMan
I would certainly think that the 250 springs would fit in the 450 without issue....although I am not certain on that.
Yea I think the fit will be the same. The problem "Not really a problem" but, what rate do they come with the 250 and 450. Might be the same but so far I can't find any online info to compare the two. Just curious I was trying to use the Race Tech sping rate generator but got an error and yz 250 was the only choice for the 05 big bikes.
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Old 01-04-2005, 09:25 AM
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Default Re: 05 KAYABA forks

Ahhh now I follow you...if I remember correctly from reading the tests in the mags the 450 and the 250 have the same spring rates as well, but again, I cannot be sure without consulting the rag itself.

You may want to e-mail shocknut...he would know for sure. If you need his e-mail, PM me Ranger.
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  #6  
Old 01-04-2005, 09:48 AM
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Default Re: 05 KAYABA forks

The 250 and the 450 DO NOT have the same spring rates.

05 YZ450F .46 kg/mm

05 YZ250 .44 kg/mm

The do use the same "size" springs though 43.6x472mm
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  #7  
Old 01-04-2005, 09:58 AM
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Default Re: 05 KAYABA forks

Go to the back of the manual (if it like every past manual) a few pages before the last page. It should have the standard spring rates and the optional spring rates for both forks and shocks.
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  #8  
Old 01-04-2005, 11:58 AM
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Default Re: 05 KAYABA forks

Thank you Satch.
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  #9  
Old 01-04-2005, 05:03 PM
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Default Re: 05 KAYABA forks

the 05 twin chamber fork is very much like the showa design

you measure oil in volume

the springs from the 05 250 should fit an 05 450
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  #10  
Old 01-04-2005, 05:04 PM
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Default Re: 05 KAYABA forks

oh, and you should use a regular 5w fork oil. I currently use amsoil medium weight
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  #11  
Old 01-04-2005, 07:54 PM
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Default Re: 05 KAYABA forks

All the big the 05 YZ's are running the same size springs length a diameter.

There are some flaws do to design,if you haven't already heard by now. This is do to copy write laws with the showa design

First off the piston design allows for trapped air to be present. with no way of purging this air.

Second: do to the displacement of excessive oil volume from the cartridge will create a negitive pressure and will also be present,which isn't good.

Russ
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  #12  
Old 01-04-2005, 07:57 PM
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Default Re: 05 KAYABA forks

You mean "patent" laws? I have heard no negative press on the 05 forks....where have you heard this?
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  #13  
Old 01-04-2005, 08:07 PM
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Default Re: 05 KAYABA forks

Yes I should of said Patent laws .
I have discussed this issue with many. Most who have been unable to bleed the fork cartridge. I have experienced this myself along with Jeff from TrakControl.

Russ
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  #14  
Old 01-04-2005, 08:12 PM
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Default Re: 05 KAYABA forks

Bleed inner chamber then bottom the damping rod with the cartridge laying on its side with the bleed hole facing up.
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  #15  
Old 01-04-2005, 08:26 PM
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Default Re: 05 KAYABA forks

There is 2 bleed holes straight across from each other so how can you have them both up.Naturally you can put your finger under one of the holes but it doesn't work. Next time when you bleed your cartridge check it after you go through the bleed proceedure. It's a guarantee that the rod will not go to full extention. Next invert the cartridge and push the rod in and you will feel and here the air.


Russ

Last edited by suspension nut; 01-04-2005 at 08:30 PM.
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  #16  
Old 01-05-2005, 09:11 AM
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Default Re: 05 KAYABA forks

Quote:
Originally Posted by Ranger_450F
The design flaw is almost the oppisite of what I read " wish I could find the Article" anyway to sum it up it said the Yamaha twin chambers used a bumper where the Honda did not and then a bunch of tech stuff that right now I can't remember. I will look around for the article I would like to hear your thoughts on what was said.
Found the article, it's on MX Techs web site. Long read but interesting to me. Suspension Nut I would like to hear if this makes sense or are they blowing smoke?

Ernie: Sorry man if I had a manual right now I would be reading it, Still in Iraq for about 3 more weeks.

Here is the article:

“I want to further clarify some function I didn't specify: there are 2 "charges" or "volume displacers": the rod charge, which is the volume displaced by the 12.5mm cartridge rod entering the cartridge. This charge only displaces volume from the cartridge, and is absorbed by the bladder chamber. The second and most influential volume displacer, is the inner tube charge, which is the inner tube entering the outer tube and displacing volume. The inner tube charge is the charge which is actuating the speed sensitive spring character. This charge forces oil DOWN by the pressure of the oil level chamber, past the restrictive barrier, compressing the bladder chamber. A technical subject that I am often discussing with suspension tuners is the "oil lock bottoming system vs. the rubber bumper bottoming system in the YZ type fork. Again, I may be biased as this is another one of my design concepts! The difference between the oil lock bottoming system and the rubber bumper bottoming system, is that the oil lock type is hydraulic, and therefore "speed sensitive", and the rubber bumper system uses an elastomer (spring) and is therefore "position sensitive". Different length (depth) oil lock cups or cases, different diameter oil lock pistons, all do one thing: they change the speed sensitive character of the system. Stiffer, softer, more progressive, less progressive, sooner, later.....I often say that damping is speed sensitive, like water: the faster you stroke your hand through it, the more resistance there is. But it is not position sensitive: if you put something in the water, it will just sink to the bottom, nothing is holding it's position. So, like a valve setting, once you set it, it is decided. The speed sensitive character is set. But in motocross, we arrive at the bottoming system at different shaft speeds: sometimes we arrive at it slowly, such as a g-out or when we hit a hole during braking, or when we hit a steep jump face. If we arrive at the oil lock at a slow speed, it may go straight through relatively unrestricted if the oil lock character is set up for high speed hits (high speed hits require a soft setting to prevent hydraulic lock, and allow full stroke). But if we set it up with a strong oil lock character, it may provide a good comfortable cushion when the fork arrives at the bottom of stroke during a slow speed, full stroke hit, but if you arrive at it at a high speed, it will hydraulic lock and feel like metal to metal bottoming, with 20-30mm of stroke still left. So then we increase the stroke of the oil lock system to achieve more action, but then we hit the top of it during braking, and it ruins the performance. I've seen aftermarket oil lock cases with 40mm of stroke! This most definitely limits the effective action of the fork in situations where it shouldn't be hitting the oil lock.

This brings me to the merits (and DEmerits) of the elastomer bottoming system. Since the elastomer is basically a spring, it is position sensitive, not speed sensitive. A coil spring is nothing more than a piece of wire being flexed. A 100lbs per inch spring will compress 1 inch for every 100lbs of force applied to it. But if you introduce speed into the situation, such as dropping 100lbs onto it, it will compress more than 1 inch, and it will occilate until it settles at 1 inch of compression. BUT no matter what speed you arrive at it, there is a cushion. If you hit it hard enough, you can go through the effective cushion, but hopefully the damping setting will prevent such excessive speeds. SO it is my contention that the position sensitive system can absorb a wider range of speeds than the speed sensitive system. For example, if you were given a choice of jumping off of several different height buildings, would you choose a 6 foot thick foam pad or a tub of 6 or even 8 feet of water? If you chose the water, you would have to choose whether to belly flop or jump straight in to prevent hitting the bottom hard. But you CANNOT change how you hit the water with a set speed sensitive character. So it would be a wiser choice to jump onto the foam pad. If you have to jump from a really high height, you may compress the pad completely and bonk your head, but at least you will have the full resistance of the thickness. As soon as you generated enough speed to hit the bottom of the water tub, you would hit with a pretty unrestricted force. Now, I am not saying that the elastomer system is perfect, far from it. In it's original testing form, Kayaba used open cell foam bumpers like on a rear shock with more stroke than is currently being used in the YZ fork. THis set up was dramatically superior to the existing closed cell "pencil eraser" bumbers. But due to reliability, we had to use the closed cell material. The open cell foam disinegrated in the oil environment. The closed cell is impervious to oil but lacks the compressibility of the open cell foam. Ideally, I believe that the bottoming system should be a hybrid speed and position sensitive system similar to the current KX system, but with more position sensitivity than speed. I have been testing a new system that uses the open cell type in a sealed environment, but it isn't ready for production yet. I know that there are legions of customers out there that will say: "my YZ forks go metal to metal HORRENDOUSLY!! They make a loud CLACK sound"......but believe me, I have tested "bottoming SENSATION" as opposed to "bottoming frequency", and the elastomer system is much easier on the hands than an oil lock hit. It may make a racket, but the actual sensation is less sharp. Our current system needs a little more stroke (it has only 15mm), and a less abrupt character”… Ross Maeda/enzo racing KAYABA

Last edited by Ranger_450F; 01-05-2005 at 09:26 AM.
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  #17  
Old 01-05-2005, 10:02 AM
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Default Re: 05 KAYABA forks

Ranger 450,
What Jer is talking about, is the Badder fork in the article that you just posted. This is not the 05 KYB design. But its good info to say the least.

Russ
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  #18  
Old 01-05-2005, 01:24 PM
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Default Re: 05 KAYABA forks

Quote:
Originally Posted by Satch0922
I did find this info and it is confusing to say the least. My owners manual doesn't tell me anything.

From RaceTech:

Must have tools TFCW 49, TFCT 35. Spring Preload Washers must go on the bottom of the spring. Inner Chamber oil level is 150mm. Bleed inner chamber then bottom the damping rod with the cartridge laying on its side with the bleed hole facing up.
Just going off looks here, but you have to remember that they're twin chamber. If Race Tech is right then 49mm on top to seperate the damper rod assembly from the outer chamber (to reveal the outer chamber housing the spring, fork oil, etc.), and 35mm to remove the comp. assembly from the damper rod assembly (to reveal the inner chamber+oil).

Click Here for an exploded view.

Last edited by Faded; 01-05-2005 at 01:27 PM.
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  #19  
Old 01-05-2005, 11:36 PM
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Default Re: 05 KAYABA forks

Quote:
Originally Posted by suspension nut
Ranger 450,
What Jer is talking about, is the Badder fork in the article that you just posted. This is not the 05 KYB design. But its good info to say the least.

Russ
Thanks SUspension Nut, Man I could have sworn it was refering to the new forks. Never ASSume I guess.
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  #20  
Old 01-06-2005, 08:52 AM
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Default Re: 05 KAYABA forks

Quote:
Originally Posted by Faded
Just going off looks here, but you have to remember that they're twin chamber. If Race Tech is right then 49mm on top to seperate the damper rod assembly from the outer chamber (to reveal the outer chamber housing the spring, fork oil, etc.), and 35mm to remove the comp. assembly from the damper rod assembly (to reveal the inner chamber+oil).

Click Here for an exploded view.
It is a 49mm on the cap. mxerhale borrowed my 50mm for his and it worked, but it wasn't perfect.
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