Has Anyone Tried These ZETA KYB AOS Pistons Yet?

They look nice, but I haven't used them. I split the std ones on my 2012 KX450F.

They work same as the other metal pistons on the market at a cheaper price point.

I suggest the "plush" version or whatever they call it not because of that... rather because kyb screwed up and didn't allow the upper chamber of ics to be equalized to atmosphere stock. Showas clone of the sss found on the Crf250r 2010 had this bleed screw (FYI)

cut the oring groove off the plastic ones and drill the sides out, they are indestructible after that

These fork caps look "nice" from zeta too but can't seem to find them in the uk ?

who sales zeta stuff? I've seen a few of their products but wasn't sure if they were legit or not, now these look really good

adam8781 wrote:

cut the oring groove off the plastic ones and drill the sides out, they are indestructible after that

Far from true.

I've seen plenty stil break. It's an enigma but they still do it.

adam8781 wrote:

cut the oring groove off the plastic ones and drill the sides out, they are indestructible after that

Derek Harris wrote:

Far from true.

I've seen plenty stil break. It's an enigma but they still do it.

I have also seen a handful over the years that had the the ridge of the lower bushing groove broken off. I can't say for sure, but I think it may be from excessive rocking because it was always on a free piston with the upper o ring removed.

montesagold wrote:

who sales zeta stuff? I've seen a few of their products but wasn't sure if they were legit or not, now these look really good

Zeta is distributed in the US by Western Powersports, so most any reputable dealership or retailer should have their items. Zeta is pretty high quality at a lower price point. I have a few trinkets of theirs on my bike.

Derek Harris wrote:

They work same as the other metal pistons on the market at a cheaper price point.

I suggest the "plush" version or whatever they call it not because of that... rather because kyb screwed up and didn't allow the upper chamber of ics to be equalized to atmosphere stock. Showas clone of the sss found on the Crf250r 2010 had this bleed screw (FYI)

Do you think the plush pistons would be an improvement for Motocross?

I've been looking at them for my YZ125.
I'll be going for the solid ones with both O-rings.

It's hard to believe that KYB would leave the pistons solid without the relief holes for 12 years, if having the piston solid wasn't for a reason. I'd really like to know that reason.

They have to be aware of the pistons exploding. Is the free piston the cheap part that prevents more expensive damage?

Is it solid for performance reasons?

What do they recommend? Holes or no holes, solid or open? 0-rings or no o-rings?

If anyone has a contact from KYB engineering that can answer these questions it would make it a lot easier to choose a free piston replacement.

And of lesser importance:
Why are the pistons open on some bikes, but solid on SSS? Is the solid piston a part of what makes SSS great?

There was a thread on this a while back with some suspension guys including ML chiming in.
I appreciate the feedback, and that drilling the holes mostly prevents the pistons from exploding, but it would be great to know from KYB what they recommend on the question above and why.

Have a great day!
Radical

Radical wrote:

I've been looking at them for my YZ125.
I'll be going for the solid ones with both O-rings.

It's hard to believe that KYB would leave the pistons solid without the relief holes for 12 years, if having the piston solid wasn't for a reason. I'd really like to know that reason.

They have to be aware of the pistons exploding. Is the free piston the cheap part that prevents more expensive damage?

Is it solid for performance reasons?

What do they recommend? Holes or no holes, solid or open? 0-rings or no o-rings?

If anyone has a contact from KYB engineering that can answer these questions it would make it a lot easier to choose a free piston replacement.

And of lesser importance:
Why are the pistons open on some bikes, but solid on SSS? Is the solid piston a part of what makes SSS great?

There was a thread on this a while back with some suspension guys including ML chiming in.
I appreciate the feedback, and that drilling the holes mostly prevents the pistons from exploding, but it would be great to know from KYB what they recommend on the question above and why.

Have a great day!
Radical

Your getting too far into the thought process.

Most people can NOT tell a difference from a drilled set to an std set.

The SSS was sold on a host of bikes - Thank MXA for mis marketing it as exclusive to yamaha. Honda 450 in 09-last year before air fork had them
kawasaki 450 had them through 2012 i think starting in 06 but certainly in 09 was identical design as yamaha had.

I see a lot of enzo forks with the ICS pistons drilled....take it for what you want - they work closely with kyb

KYB really screwed up by NOT allowing a bleed hole for the ICS air space that is sealed in the piston. If pressure does somehow build up whether its temperature rise - or leakage of pressure from outer chamber etc...it can not be bled. Also - if you take a non drilled SSS fork from sea level to altitude - the pressure in the ICS chamber will be much higher than intended.

Showa's first clone of the SSS that came on the 10 crf250 (and I do mean clone - through and through) had two bleed screws. One for the outer chamber - one for the ICS chamber. As they adopted a "drilled" style design this went away. The bleed screw is a smart and IMHO necessary addition to a sealed ics chamber.


Ultimately many people (including a host of shops) do not understand what the ICS springs influence actually is on a fork - or what varied pressure/spring rate will have on it. The difference in pressure on the top side of the ICS chamber when it's drilled and not drilled is not drastically different except when close to bottomed. The first 2/3 of the stroke drilled vs non drilled is nearly identical.

I'm using them. Just as nice as the ones that cost over double that.

Get them from Langston's Motorsports.

Radical wrote:

I've been looking at them for my YZ125.
I'll be going for the solid ones with both O-rings.

It's hard to believe that KYB would leave the pistons solid without the relief holes for 12 years, if having the piston solid wasn't for a reason. I'd really like to know that reason.

They have to be aware of the pistons exploding. Is the free piston the cheap part that prevents more expensive damage?

Is it solid for performance reasons?

What do they recommend? Holes or no holes, solid or open? 0-rings or no o-rings?

If anyone has a contact from KYB engineering that can answer these questions it would make it a lot easier to choose a free piston replacement.

And of lesser importance:
Why are the pistons open on some bikes, but solid on SSS? Is the solid piston a part of what makes SSS great?

There was a thread on this a while back with some suspension guys including ML chiming in.
I appreciate the feedback, and that drilling the holes mostly prevents the pistons from exploding, but it would be great to know from KYB what they recommend on the question above and why.

Have a great day!
Radical

Derek Harris wrote:

Your getting too far into the thought process.

Most people can NOT tell a difference from a drilled set to an std set.

The SSS was sold on a host of bikes - Thank MXA for mis marketing it as exclusive to yamaha. Honda 450 in 09-last year before air fork had them
kawasaki 450 had them through 2012 i think starting in 06 but certainly in 09 was identical design as yamaha had.

I see a lot of enzo forks with the ICS pistons drilled....take it for what you want - they work closely with kyb

KYB really screwed up by NOT allowing a bleed hole for the ICS air space that is sealed in the piston. If pressure does somehow build up whether its temperature rise - or leakage of pressure from outer chamber etc...it can not be bled. Also - if you take a non drilled SSS fork from sea level to altitude - the pressure in the ICS chamber will be much higher than intended.

Showa's first clone of the SSS that came on the 10 crf250 (and I do mean clone - through and through) had two bleed screws. One for the outer chamber - one for the ICS chamber. As they adopted a "drilled" style design this went away. The bleed screw is a smart and IMHO necessary addition to a sealed ics chamber.


Ultimately many people (including a host of shops) do not understand what the ICS springs influence actually is on a fork - or what varied pressure/spring rate will have on it. The difference in pressure on the top side of the ICS chamber when it's drilled and not drilled is not drastically different except when close to bottomed. The first 2/3 of the stroke drilled vs non drilled is nearly identical.

Thanks Derek!

So, it makes sense that bottoming may be slightly harsher with the open piston and missing top o-ring, but not really (or so slight that it doesn't matter) with the bleed holes drilled in the plastic piston.

With the open piston or with holes drilled, does fork oil make it's way where it normally wouldn't?

It could be many things, but I did notice a difference with my forks after the broken plastic piston was replaced with an open one, and the other plastic piston drilled. I can't really say what's different, just that it's not better.

I think suspension will be the next thing for me to really learn about.
It's difficult to ride and know what to change.
It's going to take some time.

Thanks again

I broke the ones in my 13 YZ250 and had them replaced with new stock ones when my suspension was done last winter. I believe they were drilled by my suspension guy, but not positive. If it happens again I will give these a try.

Don't you see a lot of this stuff on the bikes in Japan they race?

I have my OEM pistons drilled and have not had an issue with them breaking... yet. Unfortunately these alloy ones don't seem to be available for my 06 KX250, evidently there is a difference between the 450 and 250 two stroke forks.

I also have small spacers installed between the spring and base that removes the slop from the piston allowing for easier bleeding of the IC and it seems to work well for the past few years. Has anyone else done this modification and what have your results been?

smezmx wrote:

These fork caps look "nice" from zeta too but can't seem to find them in the uk ?

They are available, Madison import them and are available through any Zeta dealer

I'm no expert on this issue or done thousands of them but I've always thought it was due people not putting in the correct inner chamber fork oil quantity, either too little or too much with then not bleeding off the excess that bypasses the piston and draining from the top chamber. I always go a tad more than pump the rod the full stroke several times, listening for air trapped in the lower chamber and ensure that the pressure build up by the spring when fully compressed will fully extend the rod out again by it's own or near to it. Then I turn up and ensure all the excess oil is drained out of the top air bleed. Worked for me so far anyway.
My theory is oil trapped above the piston lessens the air volume for the piston displacement and when the fork takes a big bottom, there is a greater air pressure rise above the piston than the plastic piston can handle and the air bleed can release. It could be cyclic failure or it could be a sudden failure I don't know.
Just my 2 cents.

Zeta make some nice stuff too. Way better quality than a lot of the cheap junk out there these days.

Mr. Robinson wrote:

I'm using them. Just as nice as the ones that cost over double that.

Get them from Langston's Motorsports.

did you notice any type of difference after switching to these? low speeds? high speeds? and did they actually make them more plush and more resistance to bottoming?

I have both the LT free piston and the caps on my A-kit kyb's (ktm 450)
They do indeed give a plusher small bump ride. The a-kit kyb's have more bottoming control than the stock kyb's so I can't comment on how they would work on a stock kyb fork, but I don't see how they can be more plush and have more bottoming resistance at the same time... They are great for off road but I don't use them for MX. I switch back to the solid free piston.

Don't quote me, but I think I remember hearing something along the lines of a Showa patent on the bleed holes, forcing KYB to keep the design they had.

Has anyone used the Zeta suspension shorteners?

jdecou wrote:

did you notice any type of difference after switching to these? low speeds? high speeds? and did they actually make them more plush and more resistance to bottoming?

The damping becomes progressive when you add holes to the piston, but at the same time adds air volume. So you get a little plushness in the initial part of the travel due to the increased air volume, but with the progressive dampening you do gain some extra dampening deeper in the stroke. Good for offroad.

ZETA recommends adding 70cc of oil to compensate for the added volume, but the initial plushness goes away and you gain a lot in bottoming resistance. Better for MOTO.

On 09 - 10 CRF450r's owned both MDK & FC drilled the holes on the plastic oem free pistons when new. Never had any issues with them breaking after many hrs. of mx use.
I actually wanted to replace them with aftermarket ones on the 10 model after reading about oem broken ones & FC suggested I didn't need them. They drilled the holes on the plastic oem's & saved me a few $'s in the process.

For what it’s worth, I installed a set of these in the spring and now six months later there is no pressure in the inner chamber on either fork.

I’m not sure if it’s the o-ring on the piston or the shaft seal but either way they both failed.