Bottoming Cone Installation

Lew
If the cartridges were sealed the fork would fail to function adequately. There is enough bypass on the shaft bushing to purge the cartridge when bleeding the fork and through most speed functions. Obviously as speeds reach the higher regions the possibility of inadequate purging becomes greater. But what are you trying to purge in the first place? Aerated oil right! The oil is emulsified by the action of the rebound/midvalve piston passing through it. In order to try and control the effects of the cylinder valve you would require revalving the midvalve and perhaps reducing the amount of lift. Now here's the catch. You can also excessively emulsify the oil if you use too stiff a midvalve or one with too little clearance.
Terry

Actually there are some major discrepancies with the thought purposed here.. Midvalves and lift have very little to do with emulsification in a fork. The forks internal pressure prevents such an occurrence along with the valving, as any fork is practically set -up. (Obvious differences like valving rates) A suggestion that midvalve lift cause such a problem is certainly off base..

As for the rest of the story... I'm fairly sure that what happens inside a fork when it emulsifies is the pressure of the air spring is reduced as the fork extends in rebound. At the very top of the stroke it tends to not quite fill and we have emulsified oil in this upper space. As the fork returns to compression the emulsified oil must be compressed to a significant pressure before the valving can begin to do its work. The element responsible for this pressurization is the (Air spring- and the rod) must use significant travel before enough pressure is created. The 32mm fork cylinder is huge in comparison to the volume of the rod. KYB Engineers realized that they had to design a way around this problem and developed the CV.. IT allows quick and relive complete removal of emulsification as the fork changes directions...

It does impact the compression. (Fine valve around it, and it also works in your favor in this regard as a function of its splitting passive compression and how that relates to high speed contribution.) It also does impact rebound.. (We've got plenty of volume, I'm sure we can work around it..) It leaks when it gets dirty.. This is the quintessential problem, and the culprit behind so much myth.. so clean it!!! Easy enough...

So what's the point.. Some people like to make things simple... fine.. Some people enjoy KYB's to Showa's that's no secret.. But if you like Showa's and believe them to be a more consistent fork with more predictable action, then I'd recommend that you learn how to better tune your KYB fork.( I believe that the key wood is tune.. When you tune something by definition you make the elements more harmonious, in accordance with each other.. Tuning is not a process of removing elements that are poorly understood or under developed maybe time spent improving and understanding the results would be better than a do it yourself neuter kit...

And the lame answer some have said already! But we've tried all kinds of things, and it does not work because of that CV!!!!

Here is the provocation of the day guys... There are tuners who make it work quite well, I suppose some might consider lowering bar as fair, and reasonable... I'd think you should train harder and try to get over it yourself without lowering it..


Jer

It's one thing to understand a concept. It's another thing to understand its apllication and position in the world in which it lives. Your average bike rider has neither the tools nor the patience to constantly maintain a CV. The average tuner does not have a complete understanding of this product either. The product is released from the factory in a state of poor function. And for all this conjecture how much gain can be attained by maintaining the CV? And at what cost? Oil is aerated within the cartridge in both directions. The pressure within the cartridge does not reach the point of stabilisation until further down in the travel. Sometimes opting for an approach to a problem will not necessarily solve every scenario. But it should be the one that creates the greatest amount of benefit for the greatest number.
Terry

Jeremy Wilkey said:

Here is the provocation of the day guys... There are tuners who make it work quite well, I suppose some might consider lowering bar as fair, and reasonable... I'd think you should train harder and try to get over it yourself without lowering it..

Click to expand...

OK, i will bite.

there once was a pharmaceutical company (biggest in the world at the time), and with the advent of modern drug discovery technology, they decided to go for it...technology wise- hundreds of million dollars spent on robots etc etc etc with the view to synthesise millions of candidates for their medicinal programs. Once they got all the robotics working, then they had to figure out if indeed they could confirm that they had actually made these candidates. more technology then has do be developed and more millions spent.

in the mean time, one of their competitors just had a few guys down in the trenches doing some simple work- instead of those million candiates, these guys kept it simple and just rigged a few test tubes together with elastic bands and took the time to think about what they were making.

2 years later, company 1 had spent a lot of bling, had loads of technology but still had not made one of those millions of candiates, and all that technology was dropped since it was too complicated to get to a workable situation for the real world.

company 2 had 3 drugs in the clinic.

so, what is the moral of the story? i will let you come to your own conclusions.

as for motorcycles, if its the difference between an acceptable for and a great fork, right now, acceptable will be fine for me, much better than the crap fork i have right now. Ive taken them things apart so often its untrue, and i know my evenings are better spent in the gym.

if lowering the bar gets me past it quicker then great, currently, the little RM144 i am racing is like taking a knife to a gun fight......the yz250 is the big gun, but its no use if i cant aim it straight!

OK, philosophy lesson over! :)

I want to reply to this in my own simple way(as usual) if i invent something and after years it still has a fair few issues, it can no longer be called modern-its old school, it doesnt work as intended and its causing more problems than the thing is designed to fix.Why keep at it?? spend you time making something better is my way of thinking.I dont think we should spend years making a product work-if after 2 years its not right its not fair to the paying public to keep making it.We have to pay to own these new marvels after all.We shouldnt all need to be a fully competant suspension tuner to be able to enjoy our suspension(or pay 3 different companies before we are happy) and get a decent ride-i cant remember the last time someone said 'god these YZ forks are good from new'

Bruce,
Its a nice story! Your putting a lot more into this than you should.. The anology sounds nice, but it does not fit.. The exception is not the rule statiscally speaking and you of all people should know that!

Terry can make excuses all day long, I'm done wasting my time on this one...Good luck and have fun guys..



See ya later

Jer .....Pedal to the metal.....


There are three kinds of men: The ones that learn by reading. The few who learn by observation. The rest of them have to pee on the electric fence and find out for themselves. .....Will Rogers.....

Jeremy:

i dont know why you are letting this bother you so much- all i am doing here is trying another setup, albeit drastically different to what you are used to. Two things can happen, i will either like it, or i wont. Either way, it has no bearing on what you are doing, and if its good and i am happy then it wont make your setups any worse and if its bad, then it wont make your setups any better.

at the end of the day, i would concentrate on looking forward towards the chequered flag, and not over your shoulder to see who is behind.

If we are going to get philosphical, i can remember my grandad telling me that there is more than one way to skin a cat! :)

Cheers

lew and bruce
you guy's are on your way to some good working unit's . but the wrong valving could muddy your results , don't give up on the first try and when it comes to choosing your valving look at all circiuts and think less.
shaggy

I thought that it was harder to cavitate hydrualic fluid while under pressure? Wouldn't less bleed from the CV cause higher pressure and less cavitation? Thus less emulisied oil?

Lew the fluid gushes out of the CV because that is the low pressure area. The internal pressure from the air spring would act upon all areas of the fork still leaving the CV as the next low pressure area after the comp.adj bleed. I think Occra is referring to the low bleed carachteristics of a non CV fork as opposed to the the CV equipped units.
Terry

Actually I was refering to the CV forks. Let me try re-word it. I am under the impression that cavitation is not as prominent if the contents are under pressure.

Like Terry was refering to. If the CV "gushes" fluid out, the MV assembly would cavitate and cause emulsion easier than if the CV leaked a lot less? If the system were a lot tighter around the rod the pressure should remain higher and less cavitation would occur, or so I think.

Occra
The system is a lot tighter with a non CV fork. Cavitation occurs in low pressure areas. A low pressure area is created at the back of a moving object within a fluid or gas.(in our case fork oil) This low pressure creates an agitation of the fluid producing a foam effect within the oil. It would require a significant amount of pressure to overcome cavitation and prevent foaming from occuring.

Twin Chamber Lol.

Terry

I understand the process. I figured that a tighter system like you described could only help. To really slow down the process it would need a charge like a shock. I don't see that happening on forks.